You have your air hose connected to the discharge coupler on your compressor but compressed air will not come out of the air hose. What’s up?
It is more than a little aggravating to have your air hose plugged into your air tool, you squeeze the trigger and… nothing.
There could be a number of reasons why compressed air will not come out of the air hose.
So, let’s tackle the reasons in a logical order – from tank to air tool – to help make your compressor diagnosis and problem resolution a little easier.
1st thing to check
Have a look at your compressor tank gauge. What is the pressure reading? If your air compressor has cut in, run up to cut out air pressure, then the gauge might read somewhere in the range of 100 -150 PSI, depending on the type of air compressor you have. If you have no pressure being displayed on the tank pressure gauge, then that is likely why compressed air will not come out of the air hose.
If there is no air pressure reading on the tank gauge, then start your air compressor and let it fill up the air tank. If your air compressor won’t start, that’s another problem to deal with, but for sure, that’s also why you are not getting compressed air out of your air hose!
2nd thing to check
The tank gauge displays the pressure of the compressed air available in the compressor tank. On most compressors the compressed air flow from the tank to the compressed air regulator is unimpeded, though it might flow through a manifold that holds the pressure switch, similar to the setup shown in the photo above.
Details about the regulator operation are shown on the regulator page. Simply though, have a look at the regulator gauge. It’s either marked as such on air compressors that are fully shrouded, or it is attached to the actual regulator, as is the one in the photo. Is this gauge showing pressure?
If it is not, the issue may only be that the regulator pressure setting has been turned down to zero, effectively shutting off the air flow. The resolution to why compressed air will not come out of the air hose may be as simple as turning the knob on the regulator (in the photo, it’s the orange knob on top of that regulator) in order to increase the pressure setting to the point where you have compressed air flowing through the regulator to the discharge coupler.
OK, is there a pressure setting on the regulator gauge? If not, dial it up to about 20 PSI below the typical cut out pressure of your air compressor. Problem solved? If not, let’s press on.
3rd thing to check
If we have air in the tank, and we have a pressure reading on the regulator gauge, it’s a good bet that you have compressed air flow to the regulator.
If the regulator has a pressure reading, that’s reading the downstream side of the regulator, and that should mean that air is flowing through the regulator to the discharge coupler on the compressor. If there is no air in the air hose, then the problem may be your air compressors discharge coupler.
In the photo above we see a typical, smaller air compressor, discharge coupler.
Inside the end of the discharge coupler, right at the back, there will be a ball or flap that is blocking the compressed air that is in the compressor tank and flowing out to the coupler from blowing out to atmosphere.
The discharge coupler is “checked” meaning it has a built in check system that will not allow compressed air to flow through it until the internal check valve is opened. Normally you would open the check valve inside a discharge coupler by inserting the mating connector.
Before we do that, I would like you to try this.
Preferably wearing a work glove, and using a small, preferably non-metallic object (a pencil comes to mind), and holding the object very tightly, I would like you to slowly insert the pencil or object into the discharge coupler until it reaches the center back of the coupler. If you wish to look inside the coupler with a flashlight to orient yourself, that would be good too.
If the object you have inserted is small enough to actually touch the internal check valve, and without looking into the coupler, and making sure that no one or breakable object is in line with the discharge coupler, gently push on the ball check.
Do you hear or feel an air flow? If the pressure regulator gauge shows a pressure reading, then air should be flowing to the discharge coupler, and you should have air bleeding out of the discharge coupler when you press on the ball check at the inside back end of the coupler.
If air is not flowing, either you are not pushing in on the ball check, or you have no compressed air at the coupler.
If you are certain that you are opening the ball check inside the discharge coupler, and no compressed air is flowing out of it around the object and your gloved hand, that strongly suggests that your air regulator is blocking air flow.
If the regulator pressure gauge is showing the 80-100 PSI you would have set it for, then either the pressure gauge itself is broken (unlikely if the gauge needle moves when you rotate the regulator knob) or somehow the regulator is blocking flow. That may mean it’s time for a new regulator.
But I am going to assume that when you depress the ball check inside the coupler, air blew out.
4th thing to check
OK, so far we have found that air is flowing from the compressor tank, through the regulator and to the discharge coupler. We have determined, by pressing on the ball check int he back of the discharge coupler, that air will flow when that ball or flap is depressed.
The next test then is to be sure that the air hose connector you are plugging into that discharge coupler is actually doing its job, and as well as connecting your air hose to the compressor, it is actually letting air flow.
How? Well, when you plug an air hose into a coupler then you can usually tell that compressed air is filling the hose, as it responds to the influx of air pressure by flexing and moving. Is this happening when you plug the hose connector into the discharge coupler?
If you are not sure, then after you have plugged the air hose connector into the coupler, grab the coupler that is at the other end of the air hose, and do the poke check described above. The one to test he discharge coupler.
If you push on the ball or flap inside the coupler on the end of your air hose, and no air comes out, it’s one of two things. You either have a kink or blockage in the hose, or the hose connector you plugged into the discharge coupler on the compressor is the wrong one, and it is not opening the coupler to air flow. (See the page on couplers and connectors for more info on this).
5th thing to check
If you have air flowing out of the coupler on the end of the hose, and when you plug your air tool into that coupler, either the connector on your air tool is the wrong type to open the coupler on the air hose, or your air tool has a problem.
Hope this helps. Good luck,
If this does not resolve your problem about compressed air will not come out of the air hose, please leave a comment below.