A/C woes concluded

Bernie Benz b.m.benz at prodigy.net
Sat Jun 1 07:37:46 EDT 2002

Dave,  I'm glad that you found the problem, a most uncommon problem IME.
The more common cuutch problem is failure of the clutch supression diode.
Two failure modes, I've experienced both on different cars.  If the diode
fails shorted the clutch runs all of the time. If it fails open the
inductive spike generated by the clutch when the relay opens is loudly heard
on the radio and can screw up the ECU.  The diode is easily replaced within
the relay.  I've posted this before.


> From: Djdawson2 at aol.com
> Date: Sat, 1 Jun 2002 01:18:53 EDT
> To: b.m.benz at prodigy.net
> Cc: 200q20v at audifans.com
> Subject: A/C woes concluded
> Tonight my AC problems have been resolved... I'm feeling so great about the
> help I received that I had to post tonight.
> Trying to think of a good nickname... shall I call him "Mobil None"?  Anyway,
> my thanks goes out to Bernie for correctly identifying the location of my AC
> relay, which led to an easy discovery of what was broken.  The AC relay is
> indeed labeled 295, and resides in the far right position, middle row, of the
> aux panel... not position 4 as indicated in Bentley.
> It is a ground activated relay, and it was easy to discover that the ground
> activation post (the center one, from the thermostat) was never going to
> ground.  Quick removal of the plastic tray under the hood... thermostat a
> little buried, but a quick test indicated a resistance of over 200 ohms
> across it.  Never completing the ground, which never activated the relay,
> which left my compressor clutch permanently disengaged.
> Thanks Bernie.  That little piece of advice saved me a lot of time.
> Dave
> PS: That piece was extremely corroded... might be worth a look next time
> you're under there.

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