Well I’m now three for three on cars with annoying and difficult to diagnose a/c problems. If someone here could help me I’d be very grateful.

My ‘09 Accord does not seem to want to engage the compressor when the car is warmed up and idling (at around 6-700rpm). I’ll hear the clutch engage, the rpms will drop and the car will vibrate quite a bit, and then the clutch will disengage within about half a second or so. However, it will work just fine when driving or even at a stop if I raise the rpm up to at least ~1100. Both fans work perfectly fine. I noticed that the high side service port was leaking, so I had it replaced and the system recharged: no luck. So I brought it back in, it was diagnosed as a faulty compressor clutch. The compressor was replaced: it’s exactly the same as it was. At this point I think I may have to throw in the towel and get ready to bend over at the dealer since no one else can seem to figure it out, but I figured I may as well ask if anyone here has any ideas.

Two other things I’ve noticed:

1. When driving at night, whenever the compressor engages the headlights will momentarily dim. I did have the alternator and battery checked, but they came back ok. Is this normal?

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2. Occasionally the compressor will come on at idle, usually if I’ve driven the car for at least 20-25 minutes. However, when it does the whole car shakes and vibrates quite a lot. Now I realize that it’s only a 2.4l I4, but it seems excessive to me. My brother’s Mazda 3 only has a 2.0l I4, and you can hardly tell whenever the compressor comes on.

Any ideas?