I just noticed that my A/C is making a knocking sound, but only when it is NOT on recirculate. It sounds like somebody is tapping their finger on the dashboard about every second at a random pace.Doesn't matter what fan speed I have it set to or how fast I am driving or if I am stopped. Anybody else hear this of have it happen?
No worries. I had to replace mine not long ago. I hated driving around with Recirc on. At one point, I set it to fresh air and when it started thumping, I disconnected the switch to kill the motor, which worked fine until it got hot enough to need to turn the AC on, and since the AC and recirc switches are part of the same switch module, I had to reconnect it to turn the AC on. If it happens again, I'll disconnect the plug at the motor
I'll probably take it in to get fixed sooner or later. Hopefully it won't cost me an arm to do it. On the other hand, it is GM and it wouldn't be the Heartbeat of America if they didn't charge three times as much.