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Stopped sometime during the winter. I noticed the windows steaming up last week and yesterday it was warm enough to note that there's no cold air coming out of the vents.

First off, full disclosure, I'm an HVAC guy by trade. I happen to have a set of automotive gauges as well, though automotive AC isn't my thing. I put the gauges on last night while the system was running...no compression. The pressures were the same on both lines (~100 PSI which equates to about 85F...which was 10F above ambient, but the refrigerant is probably picking up heat from the radiator and other hot engine components under the hood). Regardless, the same pressure on both sides of a compressor means...no compression.

This would lead me to believe that the a.) the compressor's not running or b.) the compressor's valves are fried. I pulled the electrical connector off while the system was running and there was a definite change in sound...there was a slight whistling from the compressor, which went away when I pulled the connector. Also, the engine RPM's changed. That, in my not-so-expert-opinion leads me to think that neither A or B is happening. If the compressor wasn't running, the sound shouldn't have changed. And if the compressor's valves are fried, there'd be no resistance, so why would the engine RPM's change?

So now I'm confused. Any ideas where to go from here? The electrical connector to the compressor has four pins. Does anyone know what goes through that compressor? If I knew that, I could at least verify whether the compressor's being controlled properly, which rules out a HECK of a lot of stuff.

Thanks in advance!
 

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2008 RAV4 Limited V6
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Discussion Starter #3

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Your Humble Administrator
2008 RAV4 Limited V6
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Thanks, JB

Oh boy...our system has a 'neural network'. Great. Now one requires Data from Star Trek to troubleshoot a car...
Yeah, that was the first thing I thought of when I read that...:smile
 

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Wow - appears that Toyota HVAC designers get bonus points for making systems as complicated as possible . . That would explain what happened to the Good Old Days when systems and diagnosis were much more straightforward. :frown
 
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