So I got my GD3 back a couple of weeks ago after bodywork for a moderate collision that wrecked pretty much everything cosmetic on the FR corner, plus the headlight and washer reservoir. The car looks perfect now, though I had a hell of a time with the shop stringing me along ("oh it'll be done <strike>Tuesday</strike> <strike>Wednesday</strike> <strike>Thursday</strike> <strike>Friday</strike> maybe Monday"), and inexplicably, upon pickup, the A/C and the FR turn signal were dead. Come on guys, you replaced the whole headlight assembly, didn't you test all the lights on it before giving it back to me? Anyway, 45 min later they replaced a relay and everything was fine until today.

A heat wave hit my area, and I ran the A/C on recirc as usual, and it seemed that the fan was cycling a lot slower than normal - on for about 2 min instead of the usual 20 sec or so. Then the A/C quit altogether, and the fan noise was replaced by a series of *twangs* from the engine area. Regularly about every 10 seconds, there would be a pair of twangs spaced about 2 seconds apart, associated with a sound that sounded like the fan was trying to start. Additionally, if the engine was at idle, the idle speed would drop significantly every time a pair of twangs occurred.

This is an intermittent problem: for a few minutes, the A/C will function relatively normally, and then it will quit again.

 

This is a wild guess, but with a heat wave in Cali, your AC evaporator might be developing ice buildup. That would certainly help explain why it ran for awhile and then gave out completely. If your heat wave subsides, the AC would have more overhead to prevent freezing and it might not lock up anymore. As to the twangs, well, I'm out of my league now, so I'll let the more experienced forumites chime in.

 

It has not reoccurred since then, so assuming that was the problem, anyone know what can be done to ensure it does not happen again? A/C that only works when it isn't hot out is not terribly useful.