air compresor problems

It still sounds like maybe the governor is no good to me.

 

It can be a little hard to diagnose why the air drier purges constantly. I can tell you from experience that replacing the governor and the drier, or purge valve may not fix anything. You need to understand what is happening during a normal cycle. Here is how it works. The compressor will keep pumping air into the system until the air pressure reaches around 120 psi. Then the line from the wet tank, (first tank after the drier) will also have 120 psi going through it and send 120 psi into the governor. There is a plunger that will shift inside the governor that will allow the 120 psi to travel through the governor and out the small line to the air drier and into the compressor. The air out to the drier is what triggers the purge valve. The air that goes into the compressor goes into a little chamber with little pistons that hold the intake valves open all the time so the compressor will not longer pump. The main pistons inside a two cylinder compressor just push the air back and forth between the cylinders. When your system gets down around 95 psi there is a spring inside the governor that shifts the plunger back again and will exhaust the air inside the little chamber and inside the line to the air drier and the cycle starts all over again. Ok, so for the air drier to be purging every 10-15 secs means that the 120 psi between the wet tank, governor, air drier, or the little chamber inside the compressor, (this called the unloader btw) is leaking down so fast that the cycle is repeating itself every 10-15 seconds. Anything in that system could be leaking, purge valve, unloader valves and seals, governor, leaking line, leaking fittings. The best way to diagnose this is to remove the "sensing" line between the governor and wet tank at the wet tank. Then apply shop air pressure to the line so now you are pressurizing everything at once with out the truck running. Now you can track down your leak. With the system blowing off every 10 secs it will be a bad leak and hopefully easy to find. The usual cluprit is the unloaders in the compressir. That little chamber inside the compressor will have a hand full of o-rings that seal the unloader pistons. Over time, with the heat the compressor develops these o-ring will wear out and take a beating. To confirm leaking unloader pistons your shop air will leak past the o-rings and leak out the air intake of the compressor. Remove the intake hose to the compressor, if there is air rushing out, you have found your problem. All other leaks will be easy to find by sound or by spraying soapy water over everything and looking for bubbles. If you do find the unloaders leaking, and you have a Bendix compressor, the unloader kit is relatively cheap and easy to install.
Good luck.