So, the AC in my 2012 Mustang went out...at 60K. Surprise surprise. The clutch was burned up. I just changed out the clutch and when the AC is on, the AC blows cold. Just like it should. But, if/when I turn off the AC, the compressor/clutch locks up. Of course the belt still runs over the pulley but the pulley doesn't freewheel. So, I guess I will be running the AC full time until I get this figured out. I'm going to assume this is exactly the same reason the clutch went out last time but who knows. Anyone here have any clue as to WTF is happening here? Thanks in advance.

 

> Surprise surprise.

I'm... curious as to why you'd say that, seeing how my '06 has 164,000 now and the compressor/clutch/Air conditioning is still going ok... (and now I've jinxed it, watch...)

Pressing onward... I'm not saying you're wrong, because why would you say such oddities if they weren't truth for you... but that doesn't follow known physics:

Condition Normal: Clutch is fine, compressor is fine, all works as it should. A/C on = clutch engaged, compressor spins. A/C off = clutch disengaged, compressor still.

Clutch is locked up: compressor will be spinning all the time, regardless of A/C on/off, no squealing of belt. An iced up evaporator core is an end result.

Compressor is locked up: A/C on = clutch engaged, compressor locked, squealing of belt as it sands itself to smithereens. A/C off = clutch disengaged, compressor still.

These are the only conditions that should be present. That you've got a fourth one (A/C on = Normal, A/C off = squealing belt) means your car is from a dark, dank dimension of evil and you need to have it exorcised... or maybe it uses dark matter or something... or perhaps there's dark magic involved...

...and whatever the case, it sounds like it's a c-c-combo problem of both the clutch and the compressor. I'd be replacing them both, and most likely I'd probably be taking it to a dealer to figure that out.

'Cause wrong physics are happening.

Weird.

/Oh yeah... Welcome to the forums!