Good day everyone, I am looking for some Information on the air compressor unloader system on a 1997 mack (Renault) cs300p with the e3 6.2L engine. Here is the summary of my trouble shooting so far: The truck was sitting for about 5 years. Started it up and once the compressor reached 125psi the air drier would purge. The purge valve would stay open and spit out air until the pressure dropped below 110psi, then it would seal and pressure would build again. I checked for air line leaks (nothing noteworthy), replaced the complete dryer (Bendix ad-8) (no difference), replaced the governor (no difference). So I am thinking that the unloader valve is stuck closed. The problem I am having is finding any information on how to service the compressor. I saw in another forum that heat from the exhaust (located right beside the compressor) can cause valve issues. Besides 4 bolts that hold the head on the compressor I don't see any access for servicing. finding parts, information or even a replacement compressor is next to impossible here in western Canada. If anyone has had similar issues I would greatly appreciate your input. Thanks for reading!