Noisy AC

[remppainen]

I have an issue with my AC system in 2007 E150 ZRE151 Corolla.

When I put AC on, i hear buzzing noise, which pitch rises with RPM. When car comes to full stop, it takes 2-3 seconds and the sound stops. It feels like its coming from the middle of the dash or from the passenger side. Its not AC compressor, since i dont hear it under the hood. I have replaced cabin air filter, water pump and fan belt, and no effect to this. Also Alternator and Battery is tested and they are fine.

I also hear cliking noise when i switch the air flow direction, but i dont think its releated to this? Or could the blend door actuator doing something different when AC on, and when car is stopped?

AC is working perfectly fine otherwise. Blowing cold air. AC maintenance was done last time 3 years ago.

This model's AC compressor is the kind of that is spinning all time, so it cannot be its clutch/pulley or bearing.. and like i said, the sound dont seem to be coming from there..more from the dash..

 

So.. What AC system does when the car stops? because the buzzing noise allways ends couple of seconds after stopping the car.. And without AC on, the system / blower is totally quiet as it should be. I'll try to record a video of the sound soon.

 

Thanks to you in advance!

[Koush]

Make sure the AC fans on front are working when the AC is on, making sure they speed up to full speed and then switch to low speed, and then full speed again, it could be excessive pressure in the system if the fans are not cooling the condenser, which is not cooling the gas.

[remppainen]

I recorded the sound. Need to put headphones and crank volume up to hear it. There is 2 occasions of it.

You can hear the pitch with RPM, and after stopping the noise goes away. It sounds like there would be some AC motor in the dash that is making this?