A/C Stereo Clicking--Which Relay?

Bernie Benz b.benz at charter.net
Sat Jun 26 19:46:13 EDT 2004

Looks like you have the right relay.  It's been a long time since I've had
these relays opened, The 200 had a shorted diode, causing the compressor to
run all the time.  The 90 had an open diode, causing the electrical system

If you pull the relay you should have no comp. clutch action and no
electrical disturbance, Yes?  Trace out the circuit on the relay pc board.
Bentley pg. 590 is wrong, showing the clutch supression as being a capicitor
instead of a diode.  The diode, like the capacitor shown, is across the
relay contacts, anode to pin 87 and cathode to pin 30.  The other diode is
likely the relay coil suppression diode, across the relay coil.


> From: Bob Reinhardt <bobh at reinhardtmail.net>
> Date: Sat, 26 Jun 2004 15:08:17 -0700
> To: Bernie Benz <b.benz at charter.net>
> Subject: Re: A/C Stereo Clicking--Which Relay?
> Hi, Bernie,
> Thanks for your quick response; always good to get your words of
> wisdom.  Everything looks to be right as to which relay I pulled:
> Item Number: 295
> Part Number: 443 919 578 F
> Location: Middle row, last on right (position 1)
> Furthermore, the relay contacts seem to be right: 31, 30, 87, 87a, and
> a middle one labeled "T".
> I checked the diode I removed, and my mulitmeter says it's just fine,
> which I thought was weird, but chalked up to my lack of expertise in
> electronics manipulation.
> I'm puzzled, but it's a feeling I'm getting used to with my beloved
> Audi.  Any thoughts would be much appreciated.
> Thanks again for all your help.
> Cheers,
> Bob
> On Jun 26, 2004, at 2:43 PM, Bernie Benz wrote:
>> That relay doesn't look at all like the AC relays that I have been
>> into and
>> replaced diodes in.  As I recall, there are two black diodes tightly
>> squeezed on the board very close the the pin header.  No such luxury
>> of the
>> wide open spaces that you show.  Does the part number, item number and
>> location jive with what I detailed to you?  I think you have the wrong
>> relay.  Did you check the diode that you removed.  It should be open
>> from
>> your symptom.

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