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Ac compressor keeps Cycling pressure are good not low not high could the ac clutch be pulling to many Amp to cause the relay to kick off
 

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Ac compressor keeps Cycling pressure are good not low not high could the ac clutch be pulling to many Amp to cause the relay to kick off
They tend to kick out when the low side pressure gets below 20psi. If you had an excessive current draw problem it would blow a fuse or trip a breaker whatever the case may be but probably not a relay problem. What are the pressures you are running?
 

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Is the engine fan running all the time? 45 to 60 on the low side is too high. 35 to 25 would be a better range. High side in 104 degree ambient air should be easily pushing up to 300 psi at which time it should kick the engine fan on and drop back to maybe 225. I would want to remove the refrigerant and take a peek at the orifice tube to get a feel for the condition of your system. Does your truck have a working sleeper unit back there? Is there a consistent pressure on either the high or low side that the compressor clutch disengages? If they jumped all the pressure switches and the relay still disengages the compressor, I would want to know if your losing voltage to the #30 terminal on the relay socket or voltage or ground to the #'s 85 or 86 terminals. The number 87 terminal should go to the clutch. Is the switch in the control panel ok? I'm trying to remember but I think your 02 would have an orifice tube on the front unit and not an expansion valve. Also I don't think you have a thermostat which has a probe in the evaporator. Water valves should be shut off to heater core.
 
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