2nd Gen Non-Engine/Transmission AC Clutch won't disengage...

[nhincher]

I posted earlier this week about my AC system blowing up (the line from condenser to evaporator popped apart at the quick connect). The next day the batteries were dead. I assumed the two were unrelated as it's been turning over slowly lately and how could a discharged AC system kill the battery?... Well I put some charged batteries in it and was checking for current draw as I went. I found that the AC clutch would engage as soon as I hooked up the batteries, it pulled about 0. 4 amps continuously, which would explain the dead batteries. As soon as I disconnected the batteries it would disengage, so mechanically it seems fine.



Once I got the truck started the compressor clutch stay engaged all the time, I thought there was a low pressure switch that kept the compressor from engaging??? The compressor was quite warm after my short test drive.



sort of a chicken or egg question, is the clutch staying engaged because the system is low or has it been staying engaged for a while for some other reason and was the cause of my AC system failure. Any thoughts?



Thanks again!

 

[Joe Mc]

Sounds like a short in the circuit to the LP or HP switch, or, the coil (evap) temp switch (not sure if equipped with this switch or not). However, the blown discharge line more than likely was caused by the compressor not disengaging. In the short run, so you can drive the truck, I'd pull the plug for the compressor, at least this way you can get it to an auto electric shop without blowing the new line again. Let us know what turns up.

 

[nhincher]

Well I finally got a chance to dig into it, one good thing about working in the auto industry is there are plenty of cars to borrow when your breaks down... Turns out the compressor clutch relay is toast. It is stuck in the engaged postion. It's wired directly to battery power and the HVAC controls and high and low pressure switches only energize and de-energize the relay. Soooo since it was stuck closed the pressure switches could not turn the compressor off.



Bought a shop manual finally, holy wah! I can't believe I've never owned one before! For less than the price of a tank of fuel there is a huge amount of information in there. Well worth the investment for anyone who doesn't have one.