Loud Revving Noise while driving

[scaesare]

I'm going to guess that's the ECU stopping the compressor (or reducing the power) in order to maximize available power for acceleration. For the Volt, the compressor and fans can draw up to 5kW, which is still a fairly big accessory load.

I also wonder if there's any noise contribution from the A/C condenser coil fan...it may be that once there's sufficient air flow from car movement that the car shuts it off..

 

[ADN_ModelS]

I got my car back from service to get the compressor noise solved. To answer the question below: reorienting the wiring harness is for the loud compressor noise, not the whine from the fan. I can say that the fix does reduce, but not eliminate, the sound. Now, I can hear the compressor come on when the car starts, its much more muffled, but I can hear it. As others have pointed out, it goes away after a minute or so. With the fix, the noise is significantly reduced. The fan whine is still there, but I only hear that from outside the car, so I don't care so much.

My compressor is also noticeably loud, and shaking the car.

ADN, when you say that the solution is to re-orient the wiring harness, is that for the whine, or for the loud compressor noise?

 

[mknox]

I'm going to guess that's the ECU stopping the compressor (or reducing the power) in order to maximize available power for acceleration. For the Volt, the compressor and fans can draw up to 5kW, which is still a fairly big accessory load.

Oddly,I'm getting the opposite behavior. The compressor noise is fairly loud at a stop, but actually increases when I pull away from a traffic stop. Slows down again when I come to a stop at the next red light. After a few minutes of diving, it does seem to settle down a bit.

 

[Tom76]

Just noticed when parked, all of a sudden the mild hum which is normal will kick into a higher revving sound. The A/C is off and so are all temp settings. The higher revving is noticed when placed in drive. Any thoughts?