Quote:
Originally Posted by Ajgatz
Was there something specific about taking a chance that made you decide to just go for the clutch rather than whole compressor?
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Well, I do have a lot of automotive experience - 20 years worth dating back to my teenage years, just not any BMW experience prior to this vehicle. I have done a lot of AC work over the years on other vehicles and so I know that contrary to what the typical shop will tell you when they're trying to charge you $2k for a new system, AC compressors almost never just "go bad" randomly. Plus, since this was only a 5-6 year old car, let alone a very expensive one, made me fairly confident the actual compressor was not suddenly bad.
Beyond that, one can always immediately rule in/out some general AC trouble causes by eyeballing the compressor clutch. That's literally the first thing I always ask people when I get these vague questions from family or coworkers wondering why their AC isn't blowing cold - "is the compressor clutch engaging?".
If the clutch is not engaging, you know that you've got an electrical problem of some sort - it's normally low charge, the compressor isn't being fed power for some reason, or maybe the compressor isn't "receiving" the power being fed its way (aka clutch problem).
To rule in or out the clutch, in most cases, you can simply take the compressor supply lead and test it with a multimeter to see if it's receiving 12V+ when it "should" be. This is what I did on the BMW with the multimeter and testing when the compressor should be cycled on vs when it should be off. You can do this yourself too, you just need a multimeter. Even a cheap HF one will do. *edit* I see you already did this.
Traditionally, you won't see any voltage at the compressor when the system should be "off", so this was the only complication for me here as far as diagnosing it because I simply hadn't messed with any BMW AC stuff previously.
And no I was not messing around with the vehicle at all, it was totally random. Although, for the last year or so she had been complaining of just a handful of bouts of non-cold air from the AC but I could never replicate it myself. In hindsight, these were instances of the clutch not engaging temporarily then eventually it refused to engaged at all.