I have had my Pete, for four years, in that time the AC has slowly started to lose cooling capacity, gradually blew warmer air. No visible leaks, I found a BLUE capped AC fitting used to add refrigerant on the upper left hand side of the outside firewall, I looked but couldn't find another port, I don't know if the cab and the sleeper share the same unit or if the sleeper has a separate fitting that needs to be filled.
I followed the instructions on the do it yourself kit, started engine, turned the AC on full, fan on high position, and filled until the gauge read 50. Stopped filling, the AC seems to be blowing a bit cooler but it is not cold. Truth is with the engine running I can't hear if the AC compressor is running or not, looking at the tach if I turn the AC off, then on, I can't see any difference in RPM so I honestly don't know if the compressor is working.
So if anyone has knowledge of another fill port or a way for an IDIOT to check to see if the compressor is running I sure would appreciate your advice. Oh this is on a C15 single turbo Cat if that makes any difference. Thanks.