When the car is running with the interior fan on, there is a weird noise coming from by the serpentine belt. i thought it was only when the A/C was on but the other day the AC was off and the noise was still there. If the interior fan is off, then there is no noise. The noise comes on for about 10 seconds and then is off for about 20 and then comes back on again. Any ideas?

 

Might watch the A/C compressor action inside the engine compartment. Determine if the noise is occurring when the compressor is turning on. The cars climate system may be controlling the compressor using other parameters in addition to the A/C switch being on or off.

 

i'll take a look and see. Thanks for the tip!