Below are some hints about a few things to check.
Please review them.
I expect that the list of things to check will help you get compressed air flowing when you have no air out of hose.
If this is the case, start the air compressor and let the tank fill to cut out. Check if you now have air out of the hose. If not, please read on.
Actually, the air flowing from the tank should be run through a compressed air filter first, but I rarely see a filter on a DIY type air compressor.
Most air compressors have two gauges. One is your tank air gauge referred to earlier, and the other is the one that displays the air pressure setting on your compressed air regulator.
If the tank air gauge is showing air pressure, then, so should the gauge on your regulator. They may not show the same pressure though, depending on the pressure level in the tank, and the pressure setting of the air regulator.
Please see this regulator information page for details about regulator operation if you need a bit of help with what they are and how regulators work.
If there is no air pressure showing on the regulator gauge, and there is air pressure in the tank, then it is possible that the regulator adjustment knob has been turned completely down to zero, effectively shutting off the compressed air flow. If this is the case, the compressed air supply in the tank cannot reach the regulator, to alter the regulator gauge display.
Turn the adjusting knob (some need to be pushed up or pulled down to connect) until you see the pressure level display on the regulator gauge change. Continue turning in either direction until you get the desired downstream pressure level set on the regulator gauge . This setting will be the pressure that your downstream air tool will see.
That regulator setting cannot be higher than the existing tank pressure level. If there is no air in the tank, you cannot visibly adjust the regulator, though you can turn the adjustment knob. You just will not see any change on the regulator gauge.
We should now have an air pressure setting showing on the regulator gauge, indicating that the regulator is open and air can flow to the discharge coupler. Now we want to check this, as it is the place into which you plug your air hose.
Please see the page on compressed air couplers if you want to have better understanding of what they are and how they work.
When you are plugging a connector into the discharge coupler, is air actually flowing through the coupler into the air hose?
Turn the pressure down to about 5 PSI on the regulator.
Look inside the open end of the discharge coupler. At the very back of the coupler orifice there should be part of a ball check visible right in the middle of the back.
With safety goggles on, and very carefully, insert a small blunt object (pencil perhaps) to try to push on and unseat the ball check inside and at the back of the coupler. Does air flow out when you do this?
If air flows out then you now know that air is getting out of your air compressor properly, if not down the air line.
Inserting the correct connector unseats the ball check fully and locks the connector and coupler together, at the same time.
If you insert a non-matching connector into the coupler, the connector might still lock into place, but it also may not unseat the ball check fully, and little or no compressed will flow. Make sure that the coupler and connector match.
The air line will pressurize, but air typically will not flow out the other end, because it too should have a checked coupler on the end of the air line. You can tell when an air line is charged with air, simply by watching it as you plug in the connector. The line may swell a bit, unkink a bit, and might even straighten out the coils a bit as the I.D. is pressurized.
Then, you plug the connector from your air tool or air appliance into the coupler at the end of the air line, and you should have air flowing into the air tool or air using appliance.
Also, make sure the connector on the air tool matches the coupler on the air hose. If you do not have air flowing out of the hose at this point, please visit the ASK page, tell me what steps you have taken, and I will see if I can help further.