No Air pressure, plz help

Just for the fun of it, you might take the air lines loose from the air dryer and connect them. See if it builds air. If it does, your air dryer could is probably bad.

 

If he took the line off the compressor discharge and got no air, then the compressor is shot.....fairly easy to rebuild with patience...done a few now.....

 

You need the model # and make off the side of the compressor......then call the manufacturer for a rebuild kit. It's easy if your mechanically inclined....

 

If you need a rebuilt kit immediately, you could try a truck dealer or truck parts store, such as Truckpro or Fleetpride.

 

Remove the outlet line.. don't remember offhand if it's a 1" or 1-1/16" wrench you'll need, and hold a finger over the outlet hole with the engine running. If you can hold your finger there without it being dislodged, it's your compressor. However, exactly what it is with your compressor could be as simple a fix as cleaning it or replacing the whole thing.
If you're not getting adequate air pressure out of it, disconnect the large inlet line... you'll need either one or two 1-5/16" wrenches, spray some Liquid Wrench or PB Blaster into it, follow up with a shot of brake or carb cleaner, repeat that process a couple times, and finish off with the PB Blaster/Liquid Wrench. Components in the compressor head sometimes get a little gummed up and need a bit of cleaning to function properly.

You should also consider the question of where did your air leak come from. If you just started losing pressure like that, there's leakage somewhere, and, at a loss rate like that, it should be an audible leak. Do you notice pressure drop with the spring brakes engaged? Do you notice it with them released? Do you notice it, say, only when you're pushing on the brake pedal?

If it comes to that, I'd consider buying at least a new compressor head. Rebuilt ones just never quite seem to get back to being tip top.

However, did you actually verify that the compressor was the cause of the fault? I mean, if you're just going to throw parts at something whenever you have a problem and not do any actual diagnosis, expect it to take a substantial lump of change of your pocket.

King Q mentioned earlier plumbing an air couple into the wet tank... you can also put a screw-in fitting into the air drier with the same type of valve core you would use in a tire, and you air it up with shop or other external air (such as off another truck) and use the same air chuck that you would for a tire. Another way to air up your system in a pinch it to use the buddy method... hook the trailer emergency lines from two trucks together, hold in the trailer supply valve at least until you get to hold off pressure while the other truck pumps air into the system.

 

Have you looked on Ebay?