CXU613 No power to AC compressor

[Cdunlap]

I'm working on a CXU613 Mack and it has no power to the AC compressor. All switches have been changed and there's power everywhere but the compressor. Any suggestions?

[gearhead204]

does the a/c system have a charge in it? if not you may need to jumper the low pressure sw in order to run the comp. to fill the system.

[Refined Trucker]

My CX has recently had same prob. For quick fix I wired switch into wire going to comp. under hood and turn on this way. Other day had time to do some trouble shooting and found where harness plugs into top of the control unit it has bad connection in plug. Got new harness but haven't had time to install.

[turckster]

Unplug the a/c compressor and check for voltage to it (12v). If there is then measure the resistance of the a/c compressor clutch. It should be between 3-5 ohms. Anything less and the clutch is shorted internally which would cause the control panel to cut voltage to the a/c comp. If there is no or less than battery voltage then somewhere between the compressor connector and the binary switch (top of the dryer) there is an issue with that circuit. This is assuming the binary switch is working properly and there is 12v on both sides of the switch and the system has a full charge. Also, make sure the binary switch connector pins are in good shape, I've seen the pins corrode or have a bad connection and cause low/no voltage to the a/c comp.