same ; compressor doesn't come on, low side high
Ibis, I have same problem, 1998 4.0... I can figure it out based on what you said previously, but a schematic would be nice....
Possibly related, my bigger problem is if I hot wire the compressor, my low side is 100 psi, high side 125.
First: I found a pin hole in high side line at firewall. Wet foam Pad had been in contact with bare aluminum hose = corrosion on line, causing hole. Removed line, welded hole, cleaned, reinstalled, Pulled vaccuum for 45 min, no leaks. Added 2 oz. oil, almost 2 cans of 134a... System won't take any more 134. Compressor wouldn't turn on; hot wired it, got above readings. Figured bad compressor... Changed w/ compressor from my '97 which was a pressurized system (parts car - I don't know if it worked, only that there was full charge on system)
Anyway, same readings....high side actually goes down 5 psi when compressor first kicks on.... then goes up to 125psi or so...only 18 oz of 134a, but low side goes past 125 psi if I heat the can of 134a to add more. Sounds like compressor? or expansion valve to me...Stumped, please help... Gauges are harbor freight, but are hooked up correctly, charging from low side only w/ engine running, compressor on.... full charge is 44 oz?