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Re: AC warm, cold, warm, cold. Normal?

>At 09:55 AM 8/18/97 -0700, Scott M. wrote:
>>Here is one possibility regarding your A/C problem.
>>You didn't mention what type of Audi you have,
>Oops. Sorry. I have a '94 90 CS Quattro.
>> but most A/C
>>systems turn on the low speed electric radiator fan when
>>the A/C compressor is engaged. The fan is required to keep
>>air moving over the A/C condenser to allow the hot
>>refrigerant gas coming out of the compressor to have the
>>heat removed from it and convert it to  a high pressure
>>liquid. If the radiator fan is not turned on when A/C
>>compressor is engaged, and the car is not moving, the high 
>>side pressure will skyrocket and many times there is a high
>>pressure switch that will disconnect the compressors
>>electric clutch when the high side pressure gets to high. 

That's interesting, I always thought it was to keep the engine cooler!

>>When the car is moving there is enough air flow over the
>>condenser to keep the system functioning normally.
>>The 5000/200/100 Audis have a large resistor pack that
>>provides the voltage drop for the low and medium speed
>>radiator fan operation. Sometimes these resistors burn out
>>and prevent low or medium speed operation.
>Thanks, Scott. Very interesting.
>One other thing I forgot to mention was that during the times when the AC
>was blowing warm air, when I hit the recirculate button on the climate
>control, the symbol would blink on, then off (and stay off). Under less
>stressful operating conditions the recirc works just fine.

Aha!  Do you notice if the little "snowflake" symbol is on when the A/C
is blowing warm air?  The only reason I say this is that the recirculate
function will only work if the A/C compressor is running.  

>So, maybe there is a problem with the resistor pack. I'll have that looked
>at too.

Also might check the operation of the A/C high pressure switch.  This is
something else that would cut off the A/C compressor.

Does the A/C always work when you get in the car and it's really hot?



>- -Mark
>- --