Just picked up a 09 c2s and I'm having a weird issue with the AC on.

If I have the AC on and windows open there is a low freq hum inside the cabin.... If I close the window it goes away of of I open the windows and sunroof it also goes away.


Any suggestions would be great cause I can't imagine what the hell is causing this or if it's normal.

Thanks in advance

 

Have you played with the fan speed? Maybe thats the cause. Do it get louder as the fan speed is increased?

 

Is the hum an electrical type hum? Are you hearing it in the audio system? Or more of a mechanical airflow type hum?

For a cabin airflow noise try to isolate it a little more. With the fan always on, use combinations of fan speed, recirculating air button on/off, AC on/off, ECO button on/off, only driver's window open, only passenger's window open, sunroof in various positions, windows partially open in combinations, and various driving speeds.

Start with a known condition that causes the noise and experiment by changing one thing at a time to find all the variables that make the noise go away. It's too early to guess at the cause from your description.

 

It's happens when the AC compressor turns on and the idle falls slightly. It almost sounds like a subwoofer is on.


Fan speed makes no difference to the condition at all

 

Odd, I would bring it to a mechanic.

 

Will do , I wanted to make sure it wasnt a normal thing before i swap the exhaust out and the dealership blames the exhaust on it.

Thanks