There are many types of air compressors in use around North America, and though many of them look different than other air compressors, and they certainly vary in size and other areas, there are similarities that will allow you to check and see why “an air compressor will not start, by yourself and hopefully not taking it to a shop which is both expensive and time-consuming. Follow the guide below to figure out why an air compressor will not start.
Table of Contents
- Air Compressor Will Not Start – Primary Troubleshooting Checks
- Is There Power to Your Air Compressor?
- Is the Air Compressor Switch On?
- What is the Air Pressure in Your Compressor Tank?
- Try Emptying the Compressor Tank
- Air Compressor Still Will Not Start – Secondary Troubleshooting Checks
- Is Power Getting to the Air Compressor Motor?
- Remove the Air Compressors Pressure Switch Cover
- What Else Stops an Air Compressor From Starting?
- What Does the Compressor Start Capacitor Do?
- More Air Compressor Start Problems?
Air Compressor Will Not Start – Primary Troubleshooting Checks
Is There Power to Your Air Compressor?
I know, I know, it’s a dumb question, but needs to be asked.
If you are using a power bar or power strip… don’t! Plug your air compressor directly into a wall socket. The power strip may have failed.
If you are using an extension cord… don’t! You are putting a choke on the power to your compressor unless the extension cord is 25′ or less, and at least 10 gauge.
Move the air compressor to get it close to the wall socket, make sure there is power at the wall socket, and plug your compressor in there.
Is the Air Compressor Switch On?
If your air compressor is one of those that come with an ON/OFF switch, either separate from or part of the pressure switch, so please make sure that it is switched on.
Of course, if you have been using the compressor and it won’t start, the power switch will likely be on already. But just in case, please check it anyway.
What is the Air Pressure in Your Compressor Tank?
When my air compressor will not start I always check the tank gauge to see what the pressure reading is in the tank.
The reason for that is if the pressure switch is set with a cut-in pressure (the setting at which the air compressor will start) that is below the air pressure currently in the compressor tank, then your compressor pressure switch has not tripped to on, no power is flowing to the air compressor motor, so the motor cannot start.
Even if the air pressure in the tank is below the air compressor cut-in pressure setting, part of the diagnosis as to why it won’t start is to empty all of the air out of the compressor tank.
Try Emptying the Compressor Tank
Unplug or shut off the compressor.
PRV and Tank Drain
Drain the air tank by attaching an air tool or blowgun to the hose and blowing off all the air, you can drain the compressor tank by opening the tank drank valve and allowing all air (and any trapped water) to blow out the tank drain which you should do regularly anyway, or you can empty the compressor tank and test your air compressor pressure relief valve at the same time, by pulling on the PRV ring (wearing gloves is a good idea). This will allow all the air to blow out of the tank as well as make sure that the PRV internal workings actually do work. After all the tank air is gone, push the PRV valve back in and your PR Valve is reset.
By draining the tank you are emulating the function of the unloader valve just in case the one on your air compressor is not working properly. A complete description of what the unloader valve is and does is on the unloader valve page.
Emptying all of the air from the air tank allows any air trapped over the compressor piston – or compressor pistons – to escape out through the tank as well. If there was trapped air, the additional load on the air compressor motor may have prevented the compressor from starting.
OK. Plug your compressor back in or turn it on… any luck with it starting? No? OK then, let’s carry on.
Air Compressor Still Will Not Start – Secondary Troubleshooting Checks
We know we have power from the wall socket to the compressor, we also know that a malfunctioning unloader valve isn’t the problem, we are going to assume that if your air compressor has an ON/OFF switch that it is turned to on, so now what? Let’s take a look at some secondary troubleshooting checks.
Is Power Getting to the Air Compressor Motor?
Knowing that power is getting to the compressor does not necessarily mean that power is getting to the motor.
There may be an ON/OFF switch in the power supply line between the wall plug and the compressor motor. Your air compressor will also have the pressure switch in the line from the wall plug to the compressor, either of which may be preventing electrical power from getting to the compressor motor. If the compressor pressure switch has not tripped to allow power to flow through it to the motor, the compressor cannot start.
Unfortunately, if you don’t have a poke probe or a multi-meter you will have a difficult time doing the next check.
Remove the Air Compressors Pressure Switch Cover
We need to try and find out if the pressure switch has tripped to the on position, and if power is flowing through it to the motor circuit.
Carefully remove the pressure switch cover. You will see something along the lines of what the photo above shows you – a bunch of wires attached to screws.
NOTE: Be very careful. If your compressor is plugged into a wall socket, the screws (terminals) will be powered, and if you touch them and you are grounded, you might be electrocuted! If your compressor is a 220-volt compressor I recommend that you do not mess with this at all!
Generally speaking (and this is anecdotal as I am not an electrician – don’t pretend to be – and do not dispense electrical advice) the wires of a 120-volt circuit are going to be white, black, and green. Typically the green wire is the ground wire.
Also, typically, the black wires are hot in and the white wires are the hot return.
Pressure switches often have terminals where the wires are attached. Some compressor switches have these terminals labeled. You may see the terminals labeled as line (the power supply in from the plug), load (the power supply to the motor), the terminals might be marked as power supply, motor… a variety of labels if your compressor power switch has labels at all.
Using your multimeter or poke probe, you want to see if the power is flowing from the line side to the motor side, so you are going to test the motor side of the switch. Is there power on the motor side of the switch?
If your tank pressure is zero PSI, then the pressure switch should have tripped to on, and power should be flowing across the switch to the motor side. If not, your pressure switch itself may have failed, assuming it tripped to on when the pressure in the tank fell below the normal cut-in pressure setting.
What Else Stops an Air Compressor From Starting?
After you have emptied the tank and plugged the air compressor in and/or turned it on again, is there any sound from the air compressor at all? For example, is the motor trying to start and cannot?
If that is the case, and the tank is empty of air, the issue may be that the start capacitor has failed.
What Does the Compressor Start Capacitor Do?
Since an electric motor needs more power to start than may be available in a 120-volt power supply, in order for the motor to get going, it needs a boost. The compressor motor start capacitor does this.
Essentially it’s a quick discharge battery that recharges after use and is pressed into service when the compressor motor tries to start.
It charges and discharges throughout its life, and it does get used up. If the start capacitor has completely failed, then power cannot get through it to the start circuit of the motor, and nothing happens when you try and start the compressor.
More Air Compressor Start Problems?
Yes, there could be other things preventing your compressor from starting. The compressor motor itself may have failed.
Diagnosing a failed compressor motor is getting pretty complicated for a website help page.
If you have done all the checks noted here and you have not been able to get your air compressor going, and repairing compressor electric motors is not what you do, then I would suspect that it may be time to take your air compressor to the shop.
If you have any questions about your air compressor not starting, please comment below!
Haven’t heard anything from you about the unloader valve. One other thing I didn’t mention yesterday is that I had the motor off and checked out at at reputable repair shop. Nothing was wrong with the motor
Is it possible that the Float may be stuck? I have an ol 7.5 HP Curtis Ultra Pack 7E2VT8UP. I replaced the oil. It will not turn on. If I hold the reset button down on the back of the Low Oil Level Switch, it will turn on but only while I hold the button down. Once released, it will not come on.
Hi. I have 6 Gal. Husky mod:TA-2024L. It won’t start.
I’ve started troubleshooting and found that I can’t spin the motor shaft by hand.
Is it normal or means that motor or compressor is stuck? Thanks.
Did you decouple the motor from the pump drive?
Please, just answer to my question. Thanks.
Sure. No, it’s not normal. How to diagnose… answer the question. Thanks.
I have a husky 33 gallon compressor and it will not start back up after max psi switch shuts it off. Even after I use majority of stored air, it will not restart to replenish. I’ve changed max psi switch already as well… anybody have any ideas as to what is going on with it??
Hi Gary. There are a bunch of things to check noted on this page. Besides replacing the pressure switch, what else have you checked, please?
I’ve checked and replaced the pressure switch, also replaced the power switch and checked all wiring making sure no lose wires, made sure it wasn’t overheating. But that is about it. I don’t know where to go from there though, With out buying a whole new motor
Gosh, don’t buy a motor… yet. So, you’ve checked to be sure that power is actually flowing through the wires, across the switch, and to any capacitor on the motor, yes? If so, is there a capacitor on the motor? If so, and power is getting there, is power getting out the other side?
I have a dewalt 2 stage 60 gallon air compressor…I’m getting 125 volts to both legs of the motor but it still won’t start up when I turn the pressure switch to auto. Not sure what’s going on.
Any mpotor capacitors on that model? If so they need to be checked.
Is there a cut off switch on the motor? If so, check and make sure of continuity.
I have a Goodyear branded 120 psi inflator that came with my wood pellet boiler system. At the end of the burn cycle, the compressor turns on to clean the burn pot. The compressor works about half the time. If I pick it up and lightly bump it against the floor, it immediately turns on. I need this to function without being there to baby sit it!!!
Daniel, that you have to “bump” it to make it start sure suggests as loose or dirty connection. Where does the signal come from to tell the compressor to start, and also, please remove the cover and check all connections. Let us know what you found, and if you could add a photo of this device, it will help others help all of us. Thanks.
I have a porter cable 24gal that was given to me. Motor humming when I turn it on. Bled all air from tank and compressor, still humming. Took cover off to check capacitors and noticed motor won’t spin by hand. Won’t budge as if it’s locked
Well Victor, if the motor won’t spin by hand, the question is why? A humming motor can suggest it’s a capacitor problem, and that’s my first thought, but, can you unshackle the motor shaft from the pump to ensure that it’s not the pump that’s locked up? I suspect not, and next I’d certainly check the motor capacitor to see if it’s working.
One more thing. Did you relocate the compressor to a different plug this time?
No I did not. I used the same outlet while troubleshooting. I will try another outlet before I unshackle the motor shaft from the pump.
Have to turn fan by hand to get air compressor to come on it’s a senco 1 1/2 gallon
By turning the fan you are aiding in the start of the compressor motor. If it won’t start on it’s own with the air tank empty, it’s a motor issue, and if your model of air compressor has a capacitor on the motor, that may be the cause.
I have a late 60’s model Speedaire compressor, the model # is no longer visible. It has trouble starting once the pressure is above 60 PSI. I am able to get it to start by manually depressing the lever shown below, or when I start it quickly after stopping it (while the wheels on the motor are still turning.) Any ideas on why the lever is not moving on it’s own?
Aaron, that device looks like an unloader valve, triggered by the opening and closing of the mechanism inside the pressure switch. If depressing this allows the compressor to start under load, that would suggest that it is not happening automatically, and that mechanism may be the issue. Please read about unloader valve and pressure switch operation on this site if you aren’t comfortable with how they work together. Then, you may need to replace the unloader / switch if you cannot figure out from watching the operation of yours where it’s going wrong. Good luck.
I have to turn fan to get it to start running
Hi Ricky. Turning the fan is basically the same as turning the shaft inside the motor with the brushes, and that suggests that the motor isn’t delivering enough power to get the pump going.
A couple of things. One, I’ve no idea of make or model of compressor you are asking about, so if yours has an unloader valve, make sure it’s working. If it is, then the next step would be to check the motor capacitor, again, if yours has one.
How to do both is covered on the pages of this site already. Cheers.
I have a Rolair “The Bull” 2hp. I was running it a couple years ago and while on a generator it shut off and quit working. I’ve recently started trying to get it running again. When I plug in to the wall, 120, it wont start or do anything. Any ideas? Pressure switch?capacitor? Motor?
Please check the power supply from the plug to the pressure switch, make sure it gets across the pressure switch, and to the motor. If there is a capacitor on the motor, that might be blocking the power if the cap has failed. If the generator used to power the compressor was undersized, that may have stressed the cap to the max. Do a cap check, and advise. Thanks.
Kobold 30 gal model 103798 kla1583009
Clicks but does not begin to compress.
I suspect you mean your compressor is a Kobalt? I don’t recognize Kobold.
Is power getting across the switch to the motor side when the tank is empty and the compressor is powered on? If so, you’ll likely want to check your capacitor. There’s a page on this site about doing that.
Hello, I have a Husky 30gal compressor and when the pressure is over 90psi it has trouble running. It will turn on you will notice that its not running as it supposed to and after a few second it turns off and I need to hit the reset button on the motor. If the pressure is less than 90 its turn on with no problem, The pressure switch its new I change it thinking that was the problem. Any suggestion?
Which of the checks shown on this page did you do, Josue, and what were the results, please?
The only thing that I need to change is the start capacitor, all others thing I have check them or change and still doing the same thing. As I mention it will work well is the pressure is lower than 90. it will power on ok then cut off at 150psi an then I have to Turn the switch off until is below 90psi and turn it on manually if I wait to restart at 90 it will not work as it should.
Assuming there’s been no change in compressor location – which might affect the power supply – I agree. This page may help: http://fix-my-compressor.com/finding-a-new-compressor-capacitor/ .
Hi, both capacitors had been changed and the compressor still have the issue. Turn on without issue if the pressure is below 50psi. Any suggestion?
Hi Josue. I cannot find your earlier post, so I guess we’ll start at the beginning. What’s the compressor make and model, how old is it, what’s the HP of the motor, did the compressor work in this same location before, and what’s the breaker amperage for the circuit you are powering the air compressor on? Thanks.
Hi I have a Bambi 75/250 that as run out of oil and it just ticking if I put new oil in the compressor will it run thanks
Not quite sure what you mean by “ticking”, but a good first start would be to fill the oil reservoir to the middle of the oil sight glass. And then add a comment with what happened after you did this, and you tried to start the compressor again.
Have a Kobalt 26 gal compressor that will not restart. Replaced pressure switch and drained tank but no luck. I can hear motor attempt to restart but doesn’t. I am plugged directly into wall and have 30 amps. Would it be the motor or may be the capacitor? Brand new.
That’s exactly why I’m here, brand new kobalt 26 gal quiet tech, 2nd day using and it is trying to start but won’t.
Jeff, your final comment “brand new”… if that is correct, take the blessed thing back. With a 30 amp power supply there should be no issues with enough power to the compressor, and whether it’s a capacitor or not, you shouldn’t have this issue with a new compressor.
I have the wolf professional 3.5hp model. Worked a few days ago now nothing at all. Plugged directly into wall socket, drained tank completely and replaced plug fuse. I have a new start capacitor ordered, and hit the reset button. could you suggest anything else?
Regards
Steve
Have you used a multi meter to trace the power supply from where the plug wires enter the pressure switch to the motor capacitor. I suggest you not order any more parts until you determine if the power supply to the motor is the issue.
Job done, turned out to he the pressure switch was at fault, a good clean and a blow out and it’s working again
Glad to hear it. Knowing where the power goes and doesn’t go is always a good start in diagnosing a compressor that will not start.
I had a dewalt air compressor that didn’t do anything when I switched it on. I took it apart and there is a fuse inside of it. I switched out the fuse and now it works.
I am looking for a repair shop for a air compressor. this would be in the valdosta, and Tifton area
Robert, it will depend entirely on the make and model of compressor you have. If an industrial unit, the distributors for that make will help. If it’s a $99 DIY type from a big box store, often these aren’t worth the money to fix. There are companies that fix compressors in Georgia, but again, not knowing the make and model makes picking one possible.
Have a big red air machine 80 gallon air compressor, used to run , I turned it of one time and it would never fire back up. I replaced the capacitors (all 3), was getting a click sound coming from definite purpose controller , but had now stopped clicking . I’m at a loss … can anyone help me???
For a start, your “clicking” means power is getting to the controller, but since I don’t know what that is on your compressor, please add a photo in a comment with a pic of your compressor, and a closer in photo of the “controller” if you would.
Here ya go
Thanks. I know your “controller” as a pressure switch. That it’s clicking means to me that the contacts are trying to close based on the low pressure signal from the lowering tank pressure, but contact cannot be made. As a check, can you use a meter to see if there’s power on the motor side of that switch? If not, and the tank is empty of air, and the power is on to the switch, that pretty much confirms that it’s the switch that’s the issue.
It’s a Furnas, there’s a model number, and I expect you’ll find a replacement for it fairly easily. Let us know, please.
Thanks I’ll give it a shot
I have a 20gal 3hp Sanborn aircompressor motor quit couple years back , I have now replaced with a 5hp motor problem is that it will pump up to around 20lbs then it is like it starts losing power and slows down pump and motor belt not slipping so I turn it off at pressure switch!! Any help
Please tell us about the power supply to your compressor.
Same power supply as was provided before
Sure Jim. But what is it? 120, 240, what?
Sorry, 120
Jim, my experience is that you can’t run a 5 HP motor on 120 VAC. It needs 240 VAC at least I do believe. That’s likely the issue here.
I have a 21 gal 2.5 central numatic stand up and it just quite looked on line they said it was probley the pressie switch so I put new on but nothing I checked an I have electric you g to switch but there’s nothing
Virgil, sorry, but I’m having a bit of a time understanding your question. Are you saying that your Central Pneumatic compressor just quit? I assume what you refer to as the pressie switch is what I’d recognize as the pressure switch?
This comment “an I have electric you g to switch but there’s nothing” is particularly hard to get.
In any case, if you are getting power to the pressure switch, with the tank empty of air, the compressor should start. That will mean that the pressure switch has tripped, and power from the cord is flowing through the switch to the motor circuit.
Is it?
Thank you for all the info, your step by step instructions really helped, I took off cover and saw a little tripped reset switch. Clicked that. Now works fine.
Thanks for the blog. Good luck
The question will remain is why it tripped. If it happens again, or rather, if it happens frequently, that suggests an issue with power supply, either to the compressor or within the compressor circuits. Good luck, and you are very welcome.
Hey there,
I have a husky 22 gal with a Campbell housefeld running it. We were using it for siding and it blew the breaker after a while. We reset the breaker but the compressor won’t start anymore. We have power going to the switch, to the motor. We don’t think its the pressure switch cause it wouldn’t allow power to the motor if it was bad. No capacitors on this model or reset switch. Brushes look decent on the motor, 30 amp in line fuse isn’t blown, and has power to everything else. Kind of stuck here
Right on about the power to the motor. The pressure switch is obviously working.
Same scenario regarding starting if you empty the tank to zero PSI and try then? I would suspect yes.
Power to the motor, no caps on the motor, no sound of any kind from the motor, then clearly it’s the motor that is at fault.
The fuse you refer to, inside the motor housing or exterior to it? In other words, you’ve pulled the motor cover and looked for loose or broken wires in side the cover when looking for a fuse?
Off hand I’d surmise a motor short could be the reason. You’ll want to have the motor tested at a shop.
Hi ya I have Jefferson compressor which won’t start just makes a buzzing noise then cuts off I try the cut off black button but still won’t start
Andy, that’s a compressor symptom that points to electrical issues. There’s a page on this here that’s written about this and what to do about it.
You Guys nailed it. My start up capcsitor was corroded and a wire had broken. Ordered a new one and that should take care of my problem.
Thanks,
John
Glad we were of assistance, John. Have a good one.
I have a Campbell Hausfeld electric 26 gallon air compressor and it won’t run. The motor makes a buzzing noise but nothing happens.
This problem and possible solutions are found linked from the pages here: http://fix-my-compressor.com/air-compressor-problems-and-fixes/ , John. Please have a look, do the checks, and let us know what you found if you still need assistance.
I have a ingersal rand 30t it will not turn on
Please scroll to this page: http://fix-my-compressor.com/air-compressor-problems-and-fixes/
Scroll down to the section about why air compressors don’t start, have a read of the pages that apply, and let us know what you found when you did the checks.
Hi, I was wondering if you might have any information on a Rockworth Classicair 2 gallon air compressor? I received this from a friend because it was dead. I took off the cover and noticed that a 3A fuse was blown, so I replaced it and tried to power it up and it blew the fuse right away. The motor is a 120VDC Model PM301DF if that might help any.
There are only 2 components on the board with the fuse and they are a bridge rectifier and a yellow rectangle small component with might be a capacitor of some kind.
Manually turned the motor and it seems to move freely without any binding.
No burnt marks on the circuit board.
I figured I would ask the experts here to see if anyone has any ideas of why it is blowing fuses.
Also, would you know if the 3A fuse (which is marked on the board) should be a slow blow or a fast blow fuse? I have a DMM if You need to me check voltages or readings, just let me know what you want checked. Any help would be greatly appreciated.
Thanks in advance. Have a good day
If the fuse blows almost instantly, that suggests to me that there is a short somewhere, possibly in the motor windings. I am not familiar with this circuit board myself, so will not comment on the components. I hope somewhere out there who is familiar with compressor will add info.
I have the same problem in a fairly new Anvil 2 gallon compressor. No ideas where I can start to look for the short?
Rick, it occurs to me that there may be one more reason. That is, the original fuse blew, and we’re not sure why, but the replacement fuse might be a slow blow fuse. That’s one that can handle the inrush current of the compressor motor that would normally blow a “normal” fuse. Once the motor comes up to speed the inrush current dissipates and away you go. So try replacing the fuse with a slow blow fuse and let us know what happens, will you?
Hi mate i melted my start capicitor after starting issuse after long run periods on my compressor.
I have since replaced the start capacitor with an equivalent 50uf capicitor but my compressor still woll not start.
It has power it has no air in it it spins freely its turned on and i have plles the presure release valve, all i can hear is a humming sound that was the same with the old melted start capicitor installed.
Any ideas what i might be missing?
A humming compressor is one that has an electrical issue, and the most common cause of that is a capacitor. Does your compressor have two capacitors, and if so, did you check them both. If not, is it a start / run capacitor that you used, as a start cap isn’t a run cap, and vice versa.
My compressor would not start and i started researching why. And looked here and there…and maybe i am just lucky because it sure wasnt my diagnoising abilities. But my compressor has a reset button. Shabam it started right up. So check and see if you have a reset button before getting to far in. It might be that simple.
I have a power built hot rod 5 gallon air compressor. When I tried to start it this morning, it came on for a few seconds, then died and came on for about another second, then died. When I turn the switch it clicks but doesn’t start
check that your not running your electrical feed to long of a run check your amps and wiring for a start
If there was a time period between the compressor trying to start, that was probably to let the motor cool, as it sounds as if it’s going off on thermal cut out. If this is a new problem I would look at the capacitors on the motor. See the page on this site about how to test them. If it’s an ongoing problem, make sure you’ve got no extension cord, are plugging the compressor plug right into the wall socket, and there aren’t other big-power-draw items on the same circuit as your compressor.
have a june air OF1202-40m , start when on button is push, but does not stays on if button is release, replace pressure switch no changes, any ideas?
If you are saying that pushing the ON button allows power to flow to the pressure switch and then the motor, and releasing the button stops the flow of power, then it’s likely the button itself that has failed, not the pressure switch. Is it a rocker switch, a detented ballpoint type, where you push ON and it locks, and push ON again for it to pop out? Regardless, if you use a power meter to check the switch side of the ON button, and when you release it, the power stops, then it’s the switch.
Hello Nil,
I have Husky model FP209102, its hardly used. After I used it for the first time,fill it up and left it ready if I need it. I expect that if the pressure to go below certain level it should start again . It didn’t. So I thought that the pressure switch was faulty, I replace it with new one, it worked again filled the tank but again when the level went down it will not start,
So I found out that if I give the crank lever or turn the attached gear it wil start . I tested by manually letting the air in the tank to go down below the required level and the compressor start, But then if I leave the compressor for a day it will not start and the same problem.
It need another push to start. I know this type of compressor is oilless as specified, even though I tried to spray wd40 on the crank lever connection but it didn’t make any difference.
Any idea what else I can do.
Thank you in advance
Steve, have a look at the page that refers to testing the compressor motor capacitor. That would be the next step if this were my compressor.
Thank you for the advice, unfortunately, switch on the compressor push the big gear little to kick start it. it ran for a while, then start giving funny sound, the motor overheat and the circuit breaker went off ,
I guess the motor has died. I m not sure if it worth to fix any more
I m very disappointed with the quality of Husky. Very bad workmanship.
Sure, but did you check the capacitor? They aren’t expensive, and if your start cap has failed, then replacing it may fix the problem, and save you the cost of a new compressor.
Once my compressor stops it won,t restart even after the pressure drops —until it has set awhile. I can’t even turn it over by hand.
Jack, I’ve moved your question to a more appropriate page on this site. Please read http://fix-my-compressor.com/air-compressor-will-not-start/ . The compressor symptoms you describe are those of an overheating motor and you need to check to see why this is happening.
I bought a brand new titan industries air compressor, it is wheel barrow type with 2 four gallon tanks. I believe previous owner started both engine and compressor with no oil in them. Is any of it salvageable? I’m thinking the pump might be?
Here’s my problem. I have an industrial grade compressor with a huge pump and a 7.5 hp 3 phase motor. I have purchased a 15 hp phase converter to operate on residential voltage. It will trip the 2 pole 40 amp input breaker upon start. Here is the normal sequence of operation. When the compressor reaches a set point of 150 lbs, the pressure switches off the motor contactor electrically and mechanically unloads the compressor head through a small relief valve. This valve closes after the unload. Now when the next start up is called for, the head is rapidly loaded before the motor can com up to speed. This creates too much load and the breaker trips. If the blow down line is removed from the pressure switch not allowing the head to load, the compressor starts fine. I think I need a centrifugal unload switch or a electric bleed off switch with a timer. Any thoughts
Hello, I have a ridgid tri stack compressor. In new condition that I am trying to fix. When you plug in the compressor it starts to run but is hesitates and never fully starts. Not like the humming or buzzing of the motor. Also you can see the motor sparking inside the case. I do have it plugged directly into a 20amp socket. I have changed the start cap and overload switch. I have it torn down to the motor and see where the wires are plugged in. I am wondering if it is the run cap or if possible the wiring in the motor was backwards or something. The motor also has 3 other terminals with nothing connected.
Any help would be great!!! THANKS!!!
model # OF50150TS
Certainly check all caps. Then, I wonder, do you know if this motor has a centrifugal switch? If so, it sounds as though it’s seized in the run position and not flipping back to the start wiring.
Can’t seem to get it started this morning have to do it with pull rope usually starts right up doesn’t even act like I am pulling
Wow, I empty my comp. tank, direct plug into the wall socket, restart and it works well. Thank you for your guide.
I have a quincy 7.5 compressor. We have it wired to a 30 amp breaker. the compressor does not have a start or stop switch. I kick the switch and the breaker kicks, no power, nothing engine wont move…nothing happens. Its also brand new, never started and no pressure at all. Help?
If it’s new, was there not a startup kit or instructions included? Regardless, if you cannot get it going, call them to come take it back. But first, find the manual and follow the steps.
That the breaker kicks out instantly suggests that there is a short to ground somewhere. That’s what you have to look for. Be careful. 240 VAC is dangerous.
I have a 10 gallon job smart, won’t start, it has power to it. How can I bypass the switch to check it?
Daniel, a bit difficult to answer as you don’t indicate the model number of the Jobsmart, so I cannot find it on line to see what pressure switch you have. Please upload a photo. If it is the one I think it is, you don’t need to bypass the switch. It’s better to empty the tank, plug the compressor in, and use a multi-meter to ensure that power is getting to the switch, and then, with the switch cover off, that power is actually on the motor side of the switch when the tank is empty. Follow the power from the motor side of the switch to the capacitor on the motor to ensure power is getting that far. If so, it might be a capacitor problem.
Hi
My air compressor motor isnt turning on , i changed the capacitor and still doing the same thing
if you plug it it , n turn it on , it hums but fan or motor doesn’t turn on .
Please help me sort this out
Not knowing the make or model of your compressor makes this very hard to do, Mohamed. Tell us about the make and model, how you are powering the compressor, and how long that this problem has been occurring. We’ll try to help, though reviewing all the troubleshooting pages on this site that apply will give you more things to check.
Compressor had air over the piston. This site solved my problem quickly. Thanx, fix-my-compressor.com.
Thank you for your kind comments. You made the home page visitor comments section.
I have a 5.0 cfm 90 psi 2 HP. The plug in works. I was using it last night and it was working fine now all its doing when I turn it on is hums…..its a 4 gallon. What’s wrong….?
Probably a good idea to review and do the checks we have provided on this page: http://fix-my-compressor.com/air-compressor-just-hums/ , Christie.
I have bambi 150/500 bambi air compressor for dental clinic.
my compressor keep overloading.
any advise how can I solve this problem?
Milad, please provide more details. What do you mean by the compressor keeps overloading? Thank you.
My 2 hp 8 gallon air compressor just stopped coming on. I left it plugged in all night, it has a small air leak in the hose connect that makes it kick on when it gets low enough. It’s from harbor freight tools. When I went out the next day it was out of air, still plugged in, but wouldn’t come on. I have a like a breaker switch on top with a red push or pull button, and it does nothing when I push or pull for off and on. The outlet works, why did my compressor stop working? Thanks
We need to know if you have done the recommended checks, Lynard. Is there power to the socket, is there power getting to the pressure switch, is there power on the motor side of the pressure switch with the tank empty. The red push or pull button may be an ON/OFF button, and if so, you need to check to be sure that the power from the cord is actually getting through the switch when it is in the ON position. Or, this may be a thermal cut out switch, meaning that it cuts power to the compressor motor when the motor is getting too hot. That could happen when a compressor cycles too frequently, as if it had a big leak, or was being used in high air demand air tools. We need to know more about what you have checked to answer further. Thanks.
My compressor starts and runs fine on initial start up but will not restart when pressure drops. It will only restart when I push the little red button on the back of motor but only when motor is not real hot. On a cooler day compressor will restart sometimes twice before having to let motor cool down enough for the red button to restart. Thx
The red button you refer to Philip is probably the thermal cut out. That trips the motor off if it starts to overheat.
I think that the page already provides the answer you seek: “Why empty the compressor tank? By draining the tank you are emulating the function of the unloader valve just in case the one on your air compressor is not working properly. A complete description of what the unloader valve is and does is on the unloader valve page. Emptying all of the air from the air tank allows any air trapped over the compressor piston – or compressor pistons – to escape out through the tank as well. If there was trapped air, the additional load on the air compressor motor may have prevented the compressor from starting. I suspect your unloader valve is not working. Please check it and advise if that is not the problem.
OK. Plug your compressor back in or turn it on… any luck with it starting? No? OK then, let’s carry on.
My husband doesn’t dare to ask for help. It must be an ego thing…. He has a Maxair 12 gallon. It doesn’t start. I read and shared your instructions and nothing seems to work. I know that he removed the switch, the tank is completely empty and he said that he has power in the solenoid switch. He’s ready to hammer it to pieces … Do you have any suggestions. Thank you in advance Lise
Oh my, taking a hammer to the compressor won’t help getting it running… normally.
We see that some things have been checked, but don’t know if all the items on the pages about why air compressors don’t start have been checked. They are found here: http://fix-my-compressor.com/air-compressor-will-not-start/ . Perhaps you might add a comment about what the findings were when you checked each item?
My compressor is not starting. I disconnected the belt to check the motor is working, and it is fine. Once I reconnect it, the onboard circuit breaker trips. Tank is empty. Any suggestions?
My air compressor was trying to start, turned over a couple of times then would trigger the overload breaker on the motor. I live in Australia with 240V mains. I tried removing the start capacitor (150uF 250v) (which I thought was the culprit) and same symptom. The run capacitor (35uF 450V) was enough to start the compressor when there was no air in the tank, but under load – no dice. I bought a new start capacitor, installed it and now she starts without the slightest hesitation. Victory!!
Among others in the Problems and Solutions column is this page. http://fix-my-compressor.com/compressor-trips-the-breaker-on-restart/ If you haven’t, look at it and other pages referring to compressors that are hard to start or blow breakers. Your circuit breaker is tripping as the motor is pulling too much power under load and that exceeds the capacity of the circuit. It may be that not enough power is getting to the motor too, then it would overheat, and trip out. So, make sure the power supply is clean, no extension cord, no other appliances pulling power at the same time as the compressor, and if that doesn’t do it, we would suspect the start capacitor. See that page and how to check it on this site.
the circuit breaker is likely tripping out due to the motor drawing more power than is available to start it. Some easy things to check are… are you using an extension cord? If so, don’t. If the compressor is plugged directly into a wall socket, are there many other items on that same circuit trying to pull power when the compressor is trying to start? If so, that might be your compressor problem. Have a look at the pages listed under the problems and solutions column. Maybe start with this one: http://fix-my-compressor.com/compressor-trips-the-breaker-on-restart/.
I have a snap on made by Big red 20 gallon 5 hp single phase compressor, sometimes it would trip the breaker when trying to start and other times it would start right up. Now i don’t even get a hum from the motor! I wired it after removing the mounting bolts too a homemade plug..I still got no hum or noise although it was getting 110 volts..Both the start and run capacitors where attached at the time i bench tested it..The centrifugal switch and rotor seem too be fine and no burn marks on the stator..Any ideas? Thanks
I have a “Campbell Hausfeld” model#. WL600602AJ Stats are= 3.5 horse 11gallon 120V/ 15.0A/ 60HZ/ 1PH SCFM 8.1 @ 40 psi. 6.1 @ 90 psi. 125psi max. It is an older model but has been a great work horse. Only problem I started having with it was it comes on automatically when plugged in. The ON/OFF switch on the compressor its self stopped working. So when ever I want it to to turn off, I have to unplug it. It does stop when tank is full, but the switch to turn off does nothing. I have checked the wires and nothing has come loose. What could be the problem? How could it always be turned on on when plugged in?
ON/OFF switches are elctro-mechanical devices, and they fail. It sounds like your switch has failed closed, or passing, meaning that power is flowing through the switch to the pressure switch even if the switch is showing as OFF. You can replace the switch, they are not complex, and if you Google for them you will find many sources. On the other hand, the pressure switch does an admirable job shutting the compressor off when the tank pressure reaches cut out. If your air system has no leaks, even with the compressor plugged in, once the tank is full the compressor should not start again on its own, until you use air. Or, if your system has a small air leak, your air compressor will start again on its own once the tank pressure reaches cut in. Unplug it if that is the case, or replaced the ON/OFF switch, those are your choices we believe.
Thanks. Yes, it doesn’t have any leaks. It shuts off when tank is full and doesn’t start again till I use air. But I will try replacing the on/off switch like you have said. I know this problem seems weak compared to what I have read about other people’s issues with compressors, but it still annoys me having to unplug and plug all the time just to stop it. Thanks “willyr” for your time and information. 👍
Thank you for your advise and help. I had purchased a new starting capacitor which did not make a difference. I was about to purchase a pressure switch when I came up on your website. I simply opened the existing pressure switch box and lifted the switch plate up with a screwdriver, plugged it back in, and it started working immediately. So, thank you, once again.
Thanks Rey. Your kind comment has made our home page!
Greetings,
The patient is a brand new Ingersoll Rand 2545 E10-VP, one of their “fully packaged” models. New installation. Compressor motor was rewired for 460 V and the “starter” box was also swapped for a 460V unit (I-R part). We have #8 wire running to the unit, from the disconnect. This is all fed by a rotary phase converter and a step-up transformer 240-460. All of those components seem to be operating normally, other equipment on the same supply work fine. We are testing the compressor with no other machinery on, see no voltage drop at the phase converter that would indicate a supply problem. Have a commercial electrician on the job, so all wiring has by now been triple-checked.
Compressor’s “set” pressure seems to be 170 PSI, and from a standing start with an empty tank it will quickly startup and pump up. At about 145 PSI it attempts to fire up again to recharge and cannot. It will sometimes get a couple of spins, then groans, then the overload trips. Overload is set to 14.5V. Temporarily setting it to 15.5 has no effect.
Much testing and head scratching has taken place, during which we discovered that if we bleed the tank pressure to as high as 90 PSI it can and will restart and recharge, but anything over 90 tank pressure causes the non-start and eventual overload.
Reading this excellent site (and others) pointed me in the direction of the unloader switch, which I believe I have located integral with the pressure switch at the top-center of the tank (horizontal) – at the end of a successful cycle a valve is actuating and there is a 5 or so second hiss of air escaping from beneath the pressure switch. I can’t feel or detect any leaking after this cycle completes.
It sounds like that is operating properly, but the symptoms of my issue seem consistent with an unloader switch problem. Can you shed any light on the issue,. point me in the right direction? I-R service has been contacted and I am waiting for a return call, but I certainly would value any intel I can gather too.
MANY THANKS for this excellent site.
You are welcome. Thanks for visiting, and I hope we or others can help you with your IR compressor issue. Yes, it sounds as though the unloader is working properly. That being the case, to our thinking, the problem may lie with a weak or failing start capacitor. See the page on this site about how to check yours, and please let us know if that was the cause.
Thank you very much Willy.
Although the unloader feature WAS venting post-recharge, it was not venting the entire piping circuit between the cylinder and the tank check valve. An I-R technician visited yesterday and when we manually vented the piping (about a 2-3 second tug on the relief valve evacuated all the pressure) via the pressure relief valve at the left rear behind the smaller cylinder, the unit started and recharged normally at it’s set pressure.
Not understanding or seeing what’s at the end of the compressor crank where part of this system is, I can’t theorize what the specific problem is, but they assure me it will be resolved. I expect a call from them today.
MANY THANKS for maintaining this excellent site – info on this site is what put me onto the unloader as a possible culprit and that certainly helped to resolve it faster.
We are glad to have been what little help we were, Nils.
Hi, my 5.4 iron horse compressor won’t run. Plug receptacle is good, on/off switch is in the on position, no air in tank, power cord is good, never run out of oil.
Kevin, a couple of things to check, if you will. You say you have power at the receptacle. Good first check! That suggests that power is flowing down the power cord to the ON/Off switch. But, is the power getting across the ON/Off switch? You need to use a multimeter to check the motor side of the switch to be sure that the ON/Off hasn’t failed. If power is getting across the ON/Off switch, check to be sure that it’s getting across the pressure switch, as, with the tank empty of air, the pressure switch should have tripped to ON, and power should be flowing across the points to the motor circuit. If power is getting to the motor circuit, the next check is the start cap. All of this is covered in the page about air compressors that don’t start, and you will need to do these checks, or have someone do them for you, to diagnose where the fault in your air compressor lies.
Dear Sir,
Greetings,
We are having Euromatic Air Compressor (50 LT)
It is set to cut off at 110 PSI and to re-start at 90 PSI, but the compressor doesn’t start.
It wont start till the tank pressure becomes zero.
Motor gives jerks to start but not thru at this time motor is drawing 30 Amps current.
This is 3 times more that the staring current.
Would like to know what is the problem?
Is it a motor or compressor piston problem?
Regards,
George J. David
George, we were not able to see an image of your compressor, so cannot be sure, but feel that you need to check that the unloader valve is working. If the air compressor unloader valve has failed, there is too much load for the air compressor motor to overcome, and it clicks off on thermal overload, after drawing too many amps when trying to start.
my iron horse 5.1 cfm @ 90psi portable air compressor 1hp max pressure 125 psi 6.5 gal ran out oil and wont start the tank is empty and it is pluged in to the socket what els can i do
Are you saying that your Iron Horse air compressor ran for some time without any oil? If so, heat may have damaged the pump and the motor. If you have power to the socket, and that confirms power to the compressor, and if the tank is empty, and absolutely nothing happens when you switch it on or plug it in, did you do all the checks referred to on these pages?
My cambell hausenfield aircompressor will not start. My ground metal piece came out. I checked to see if there was air in the tank. It is a 200psi rated aircompressor can you help.
Johnny, we’re not quite sure what you mean by “ground metal piece”. Why not upload a photo of it so we can see what we are talking about? Also, please indicate the model number of your Campbell Hausfeld compressor too, K?
My compressor won’t start because it is jammed. We changed the capacitor because it blew, thinking that would fix it, but the engine itself still sounds like it is jammed. Any ideas on what to do?
A bit hard to give advice, Carlos, when you don’t indicate the make or model. Assuming you’ve got a pump sheave that’s driven by a belt from the motor, if you remove the belt, can you rotate the pump sheave by hand, or is it seized?