Defroster screeching noise

I have a 2006 Tacoma (std cab, 2 wh, 4 cyl). Recently, when I turned on the A/c there was a screeching noise and the a/c system blew warm air. I was told the compressor needed replacing but due to the cost I decided I would drive with the windows open.

Today, there was a heavy rain and the windows fogged up. I diverted the air to the windshield and lo and behold, I heard the same screeching noise that occurred when I turned on the a/c. To be clear: The a/c was OFF; I had the fan on and the air blowing into the cab; I then diverted the air to the windshield and the screeching started; I diverted back to the cab and the screeching stopped. I did this several times to be sure.

So the issue seems to be: what is the common element(s) between the a/c and the defroster? There must be some common part of the HVAC system. It can't be the a/c compressor because the compressor is not involved with defrosting the windshield. Is it the a/c clutch? I don't know, does anyone out there know?

Any help will be greatly appreciated.

 

The AC is used everytime you use the defroster.

 

To ensure everything stays nice and used during the winter months.

 

Go to the fuse panel under the hood and remove the MG CLT Relay. This will stop the clutch on the compressor from engaging and the screeching will stop.

 

Jimmyh: Thank you very much. I feel foolish that I didn't think of this because when my a/c stopped working I went to the fuse box to make sure the MG CLT relay fuse was working properly (swapped fuse with one that I know was working).

D

 

and did this fix your AC problem as well? just curious... or just the whining?

I too am experiencing that whine on defrost as well as AC.

 

i just went and replaced the relay and no dice

 

it is your blower motor