[V8] Air Conditioning Q's

[NicolCS at aol.com]

Why are you worrying about the switches?  Check the HP switch for continuity. 
Continuity=probably fine. While the system is empty, check under HP and LP 
switches; if there's a schrader valve under switch (and that's likely) you can 
change them after the system is charged if you need to.   I'm pretty sure the 
system uses an orifice tube, the car has an accumulator so 99% sure it has an 
o-tube.  If so, it should be downsized.   Change O-rings. FLush system except 
compressor. Drain oil from compressor. Prefill compressor with proper amount of 
E100. Change the dryer. Evacuate and check if it will hold vacuum.  If OK, 
add vapor to about 50 PSI and sniff (with detector) for leaks.  If OK, add 
refrigerant until pressure prevents any more; listen for LP switch. Rotate 
compressor by hand to verify no oil blocking. Start system.  If compressor won't 
start, bypass LP switch to force compressor ON and slowly meter balance of 
refrigerant in through low side.  Remove LP switch bypass and check for cold at 
entrance to accumulator and cool at exit. If you have cold at the accumulator, 
you're good to go!  IME, 90% of the time, all that's wrong is a refrigerant leak or 
compressor failure.  If you wanted to be picky, you could change the LP 
switch to a 134 type, but it should work with the existing LP switch, it just won't 
be "optimal".  
 
Craig Nicol
90 V8Q
95 S6 avant



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