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re: Re: TQC heater core replacement (Now A/C info)


Running the A/C compressor while in defrost is a great way to remove 
moisture from inside the car especially if the recirculation door is 
closed. The moist air condenses on the evaporator and drips out the drain 

The 4000 cars probably use an A/C system that runs the compressor all the 
time and then regulate the evaporator pressure to control the amount of 

The 5000 cars use a Cycling Clutch Orifice Tube (CCOT) system (from 
General  Motors ie Cadillac) that turns the compressor on and off to 
regulate the evaporator temp. There is an orifice tube (no evaporator 
valve) that is used to somewhat regulate the flow of liquid freon into the 
evaporator where it expands and absorbs heat from the interior of the 

I recently replaced the pulley bearing on the A6 GM compressor on my 86 
5000CS T and found that removing the front bumper allowed the front 
compressor hub to be removed without discharging the A/C system. The 
bumper comes off sooooo easily, two bolts and it slides right off. You do 
need various special tools to remove the clutch hub and pulley, and then 
to press the hub back on etc.

I am not familiar with the 4000 A/C controls but an compressor on/off 
switch would be nice for those you don't want to lug down the engine after 
first starting the car with the defrost on.

Scott M.

Robert Phillips <r3rfp@dax.cc.uakron.edu> Wrote:
| On Mon, 30 Jan 1995, Alan Cordeiro wrote:
| > from -RDH
| > 
| > >windows clear. Audi, in their infinite wisdom, of course 
| disallow run-
| > >ning the AC and heat at the same time (*I* have since 
| fixed that in my
| > >car), so you can't defog the air . . .
| > 
| > Tell me more, this has been one of my gripes on chilly + 
| rainy
| > days. However it was a nuisance, low on the priority to get
| > attention, so I have'nt got around to it yet.
| I realize that I am bucking the trend here, but I don't want 
| the A/C to 
| engage every time I defrost, especially on bitter cold 
| mornings.  I had 
| owned only late-model(at the time, 83-86) Fords before I got 
| the Audi, 
| and that was one major complaint that I had about the Ford 
| system.  I 
| just disconnected the pig-tail at the compressor and had no 
| more 
| worries.   To me, the A/C seems to "drag" on the engine too 
| much to 
| warrant it on with the defrost all the time.
| I am not advocating Fords, but is this an American thing?
| 			---Bob
| 		--87 4000S, 4-cyl