Air Conditioning Belt "Chirps" When Compressor Kicks On.

[Tom Mullane]

Hi All,

'Tis the season for AC woes, and with my aging fleet at least one car has
some sort of issue this time of year but this year both the 200 and Coupe Q
are acting up.  Both vehicles are doing the same thing:  When the AC is on,
they can run happily at idle for hours, but at highway speeds there is a
chirp from the belt (or clutch) when the compressor engages.

The 200 isn't too bad; it blows nice cold air and seems to function
normally, except, of course, for the chirp.  The CQ, on the other hand,
seems to have an advanced case of the 200's illness; the AC blows "cool" -
better than having the windows down - and the compressor only cycles on for
a few seconds before clicking off.  We took the Coupe for a 250 mile drive
last weekend, and the AC belt did not make it home with the rest of the car.
First sharp chirps, then squeals (150 miles in), then smoke, then silence.
I replaced the belt today, and the AC is working OKish at idle again.

Yes, both belts are tight.  Yes, both belts are new.  And yes, both cars are
black;-)

Anyone have any ideas?  Compressor?  I don't think it is an obstruction in
the system causing a high pressure problem; the chirp is on start-up.  I
assume both compressors are the same?  I assume both systems are R-12?  As
an aside, conversion to a different refrigerant is not an option yet; I
still have a few pounds of R-12 kicking around.

TIA, and stay cool.

Tom Mullane
Hartford, CT
91 200Q
91 CQ
99 A6
Etc.