Helping my neighbor with his 1996 F 350 dually. The A/C was out for years. I Found the schrader valve was leaking. Replaced, charged worked great for overa year.
A/C went out again. Clutch will not come on. There is no power at the clutch connector.
50/270 @ 90 degrees on gauges. Jumped low pressure switch just to see- no change
Fuse in cab good, power both sides. Cannot find a relay for A/C. Online says there isn't one.
Applied power directly to compressor- engages and blows cold air. No other issues detected.
Question- how can I check or bypass the High pressure switch to confirm its not an issue. Where can I find a wiring diagram for the climate control panel inside the cab. I need to start tracing the reason for no power at the clutch and not sure where to start.
this is the wiring diagram for the A/C circuit. if you have power on the low pressure/cycling switch, check for power at the high pressure switch on the connection block on the back of the compressor.
At 270 PSI, the high pressure switch should be closed. It opens @ 470psi
Sounds like either the high pressure or low pressure switch, how does the switch in the cab feel? Pull the trim, pull the switch out, look at the schematic and start testing power in and power out to the ac system.