Chrysler Repair: engine rpm and AC, gerard parkin, compressor operation

Question
Dear Roland,

Sorry for my slip, but it is an automatic.  But the sound did seem as if a "clutch" was sliping. The
clutch on the a/c sounds like a better option because when I turn the fan off everything is OK.  
However, the bit that puzzles me is that I do not have the ac cooling unit turned on.  There is
also a random "hissy" noise that I get from the AC unit, as if gas is leaking.

Thanks for your help!

All the best

Ged

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Followup To
Question -
I have just noticed that the engine of my 97 Voyager was "wining"
when I accerated but the car didn't respond accordingly.  It seemed
to me like the clutch may have been slipping.  However, by
coincidence I found that if I turned off the AC then everything
became OK.

Do you have any suggestions?

Best wishes

Gerard Parkin
Answer -
Hi Gerard,
I have not experienced that sort of behavior so I am guessing about this one. If the powertrain
operates normally when the A/C is not activated, no whining and no sense of clutch slipping (do
you have a tachometer to actually detect such slippage?; even just a test instrument with a tach
capability would help to prove whether there is actual slippage or just an impression due to the
whining) then I doubt that there is anything wrong with your powertrain's clutch (and I assume
that you have an actual clutch and a manual transmission rather than a torque converter and an
automatic transmission, correct?).
My suspicion is that the noise may be coming from a different clutch: the clutch on the a/c
compressor. (Of course it could just be slack in your a/c compressor drive belt that is causing
the whining so check that possibility.) The a/c clutch operates electrically and is supposed to be
released by the action of the engine controller when it senses that the throttle is fully open
(shutting down the compressor operation) when you accelerate the engine at full throttle, so that
may have something to do with the noise. If the clutch didn't fully release under full throttle
condition then the a/c clutch would possibly be the whining noise.
So I believe if you went to a competent independent a/c shop they might do a road test with you
or be able to come up with an explanation. Write back if I misunderstand and in any case if you
get an explanation from the a/c expert.
Roland  

Answer
Hi Ged,
I agree with looking into the AC unit rather than anything to do with the automatic transmission or the torque converter. By the way, if you ask the heater control unit for "defrost" that will automatically invole the AC compressor because it is used to "dry" the air by cooling it before it is directed to the windshield, so that is how the compressor and its clutch could become involved without specifically pushing the AC button.
Roland