Date: Sun, 11 Jul 2021 01:34:01 -0700
Reply-To: vw_van_fan_Mark <madvws@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: vw_van_fan_Mark <madvws@COX.NET>
Subject: Re: low idle when AC compressor is on
In-Reply-To: <CAMjSMWtBqhgwTxb=Kib2G6rmWL_MJAZgD9-Y-Db0pTv7Wn2Y+g@mail.gmail.com>
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You are right that the idle control to A/C wiring connection is not well
covered in the Bentley.
I can try to cover it better here.
First, page 24.48 shows the injection system components including the
idle stabilizer control unit.
Next to it is shown the wiring socket for it. It is labeled "relay
adapter" for some odd reason.
One of the wires in that socket is the wire that connects to the A/C
compressor clutch.
Second, page 97.144 shows the late model A/C wiring.
In the lower right corner is the A/C compressor clutch wiring and shows
a wire feeding down labeled "to idle stabilizer control unit, J142".
Third, page 97.207 shows the "idle stabilizer control unit, J142" wiring.
Pin 2/K of the device shows a wire "W/G" white/green stripe.
Sadly the wire just ends there with a connector number T1K.
That wire should be labeled "to A/C compressor clutch" and if it were
many people would have been saved some grief.
So there is in fact a wire feeding the idle control unit from the A/C
compressor clutch. It is a long white/green continuous wire within the
Digifant main fuel injection harness. Sadly on page 97.144 it shows the
wrong color on the Digifant side of the T1a connector shown.
Falsely labeled only R/BL instead of W/G as it leaves the page.
To summarize, there are errors and omissions in the wiring involved.
a. the critical wire is not fully labeled at the idle control unit page.
b. the critical wire has the wrong color shown on the A/C wiring page
c. the critical wire connector is labeled T1k on one page and T1a on the
other
Hope that helps.
Now, find the end of the thin white/green wire under the ignition coil
area. It should have a yellow plastic end and should connect to the
compressor clutch power wire. Make sure everything looks good.
To test things, UNPLUG that wire and start the engine and let it idle
normally. A/C OFF
Next jump 12v to the white/green wire and make sure the idle speeds up
each time you briefly touch 12v to it.
If the idle doesn't speed up with this test then look deeper at whether
the wire has continuity all the way to the idle control unit socket
mentioned above. More help as needed.
Mark
Ryan Cresawn wrote:
> I spent some time studying the wires connected to the compressor, testing
> them for continuity, and studying the Bentley which I have not found very
> helpful with this wiring issue. I admit I could be looking in the wrong
> sections......