More Help: E30 AC compressor problem

["Alexander Fadeev" <afadeev@xxxxxxx>]

Hey guys,
	I am back with my AC no-power to compressor problem. 
	Just got the car back from my new X-mechanic - Richardson Import of=
 Richardson (Dallas suburb), TX. They had wall jobbed my wife's '90 325is=
 for 1 hour of labor to announce that "there is something wrong with the=
 power in the dash". This is after I brought the car _telling_ them that=
 compressor is not getting any power and I would like to know if that is=
 because the low R12 pressure switch is kicking in.
	The morons claimed they "saw" some "small" leaks. This is without=
 measuring the pressure in the AC system or doing anything to trace they=
 suspected leaks (would have been another 1 hour of labor). I still don't=
 know if I have any freon.  ARRRGGGGHHHHH.

	Does _anybody_ know how I can test the low pressure switch activation=
 without any gauges? And where is that switch? What else could cut the=
 power to compressor?
	The earliest appointment at the local dealer is next Wednesday and it has=
 been over 100F for the last 20+ days in Dallas!!!

	To the list of tests mentioned in my original post I would like to add=
 that I have:
  3). Checked the fuses. All are fine. As far as I can tell from the=
 Bentley there are no relays in the AC system.
  4). Swapped the AC button panels between mine and my wife's cars.=
 Compressor still doesn't get power. 
  5). The AC 'on' light comes on and the RPMs rise, but the air is HOT.=
 What is raising the RPMs if the compressor is not running?
  6). Somebody had suggested that if the bottom vent control lever is not=
 open, then the AC switch in the lever might turn off the compressor (in=
 E30s only). Moving the lever did not help.


TIA,
Alexander Fadeev

P.S: I _really_ miss my old mechanic Craig at Twin Star in Richmond=
 Virginia. The guy was honest to a fault (former BMW Club racer as well)=
 even though their shop had grown to near dealer throughput.



=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
my original message:
	I've got an interesting AC problem in my wife's car (90 325is).
Namely, the AC has suddenly quit blowing cold air and now specializes in
the ambient 100F+ air. The system failed suddenly without any prior
warnings (worked before lunch but started blowing hot air after the meal).
	I had tried the limited testing mentioned in the Bentley and
have discovered two anomalies:
  1). None of the three wires in the compressor wiring harness have any
voltage in them with AC turned on (my car has 12V at the third 'center'
connector). 
  2). The 'bubble' in the R12 sight glass does not move. This one is
probably due to the fact that the compressor is not running. 
	I had tested the AC switch from my E30 (AC works in mine) and
that did not change the no-power to compressor problem. There are no
visible corroded connections anywhere to be found. Bentley suggests to
check for a faulty in-line diode on the compressor. How exactly do I do
that? What other sensor inputs does AC system take into account that may
cut power to the compressor?
	Any help would be most appreciated.


- --
Alexander Fadeev
2x M20B25
afadeev@domain.elided

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