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1st off, hello. I just picked up an 04 CCSB 4x4. I'm all about reading and gaining knowledge on things and I need to learn the Dmax way. With that said I'm hoping someone can shed some light for me here. The a/c blows but not cold. I thought it might be low or the dual climate control was whacked, but I've discovered that I'm not getting any signal to the compressor clutch to engage. I've verified fuses under the hood and in the cab, I've swapped relays and still no dice. Is there any type of interlock that might cut the signal like overpressure/low pressure? I think that is the case on some other GM vehicles so... I've traced the wires as far as I can and don't see any damaged/burnt wires. I do have an appointment in the morning to evac and recharge the system. Hoping that'll do it, but if not any help would be much appreciated. Thanks and hope to be part of the site for a while. :drink
 

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Welcome! Lots to learn here. Also you will probably get bit by the "mod bug", and all your money will dissappear. :) Sounds like you could be low on freon or have a pressure switch stuck. My money is going on low freon.
 

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Yes, there is a cycling switch that sends power to the compressor when the AC is on. It is mounted on the accumulator or the line next to the accumulator and looks like a oil pressure switch. If the freon is low, it will prevent the clutch from operating. It is used to cycle the compressor to maintain correct pressure in the evapator. Remove the connector and check for voltage. If you have volts, jump accross the connector-- the compressor should start. You could also jump from the battery to the clutch with the connector disconnected. Run it a few seconds and see if the large line at the compressor is cold-- this is the low pressure. If the line stays warm with the compressor running, you probably have low freon.

No not run it more than a minute as it could damage the compressor
 

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Discussion Starter #5
Thanks for the help guys. I was going to see if I could jump the pressure switches, but it got late. I did hotwire right to the clutch and verified it was engaging while the truck was off. Looks like it was just low, shop evac'd and recharged. Held vac good and don't see any signs of a leaking fitting. Nice cold a/c again. It's a must have out here in AZ during the summer!

Luckily the truck already has a few decent mods, but I've been diagnosed with the mod disease and it'll probably just be a matter of time before something gets changed, polished, upgraded, etc... Thanks again!
 
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