jbrob007

This is a new one on me... granted it doesn't take much

84 Euro. I'm hearing a rather strange thumping noise while driving the car with the AC on... Turn off the AC and it goes away. Turn it on and it comes back... sounds like a mechanical noise (not inside the car). Checked out compressor and everything appears to be in order from an external view... good belt, alignment, etc. AC blows very cold, but the sound has me worried as I don't want to screw up the compressor.

Anyone else experience this symptom? Any suggestions where to start would be greatly appreciated.

Joel

The Forgotten On

Check your interior vacuum valves, a leak can cause weird noises and odd functions.

Check the blower motor as well, change speed settings to see if the sound is related to that.

jbrob007

The blower motor had no effect... Fan up, down, etc, or changing the position of the vents via the control panel = no effect. All the interior HVAC valves / pods & vac lines were just replaced when we reassembled the car.

The only thing that changes the symptom is hitting the AC button and energizing the compressor... or turning it off.

Mrmerlin

did you replace the pod in the pass foot well

gazfish

Can you locate the source of the noise with the car stationary and the hood up. Maybe the compressor clutch is cycling?