Not building air

[Joe Ditchkus]

My compressor only builds air up to 90 lbs. this just started. I put a new air governor on and same thing. Could it betheair dryer? It is not constantly unloading seems normal.What size uion do I use if I want to eliminate air dryer to see if that is the problem?Thanks Joe D.

[j hancock]

Could be the unloader valve in the compressor is messed up or some sort of restriction in the air line to the unloader. There are usually rebuild kits available.

If the truck has an AD-9 dryer, there are rebuild kits to tune them up. Are the air tanks blowing pretty clean when the tank valves are opened?

Not sure what size hardware you need to bypass without looking at it.

[gearhead204]

if you hook it up to shop air will it go higher? it sounds like a unloader issue, but I would hook up to shop air to double check for possible problems

[Joe Ditchkus]

Thanks for the replies. Nothing in tanks when I drained them. I eliminated air dryer today still only 90 lbs. of air. Joe D.

[Hook n ladder 1]

Get yourself an unloader rebuild kit. Its about $15 and if the bolts come off easy, and you can clean off the old gasket, it whouldnt take more than about 5 minutes. Its on the top of the compressor.

[Joe Ditchkus]

Thanks for the replies. I hooked shop air to it and line from compressor to wet tank had a hole in it under cab. With engine running you could not hear it or reach to feel it. Joe D.

[gearhead204]

joe glad you found it! i have found a secondary air source too be a great tool in diagnosing air system problems. eng. noise moving parts etc. can make it a bear sometimes.