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

["Scott M." <scottmo@teleport.com>]

Mark,

Here is one possibility regarding your A/C problem.

You didn't mention what type of Audi you have, 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. 

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.

HTH
Scott M.