Squealing/Shrieking noise from behind climate contol head....

[Stephen Ankney]

Listers,
OK, I've been having this little problem with a squealing noise coming from 
behind the climate control head on my 88 5000S. At first I thought it was 
the aspirator motor for the interior temp sensor going bad so I replaced it 
with a known good one. This seemed to work for awhile but now that I'm using 
the CC(heat) more the squealing is back. I thought that maybe I could just 
disconnect the aspirator motor and be done with it but would'nt you know it, 
the noise is still there after I disconnected it! So obviously it's not the 
aspirator motor...

So...what else could it be? The noise is centrally located somewhere behind 
the CC head or maybe coming out of the vent directly on top of the CC(which 
makes no sense)...

Has anyone ever experienced a CC head that started to squeal when going bad? 
Anything else that could possibly be in that area that would do this?

Symptom recap:
CC head appears to be working fine. Heat/air comes on fine and blows out of 
all vent options. After a couple of minutes of running there is a squealing 
sound that gets louder and louder and then stays constant...unless you put 
the heat/air on high, then it goes away....

The noise is so loud that it can be heard from outside the car. Could it be 
something in the plenum area? Thats where the noise seems to be coming from 
the loudest when listening to it from the outside. I'm stumped...I thought 
for sure the aspirator motor was the culprit...

BY the way, the blower motor was replaced with new one a year and a half 
ago...

Any ideas? I going to try and track down a used CC head tommorow and see if 
it makes a difference. Thanks!

Steve
88 5000
Michigan



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