Date: Sun, 11 Jul 2021 20:46:41 -0700
Reply-To: Ryan Cresawn <jrcresawn@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Ryan Cresawn <jrcresawn@GMAIL.COM>
Subject: Re: low idle when AC compressor is on
In-Reply-To: <e0246686-2de7-3f00-0d3d-7a5f2d2bed54@cox.net>
Content-Type: text/plain; charset="UTF-8"
Mark,
I followed your troubleshooting advice by connecting the positive terminal
on the alternator and the W/G signal wire. The idle rpm increased from ~880
to ~1000. I sprayed contact cleaner on the contacts of the yellow
connectors for the single wire and bent the receptacle contacts to add a
little more friction to the fit. Now engine idle increases when the
compressor is on as it should and it does not want to stall.
Thank you,
Ryan
On Sun, Jul 11, 2021 at 1:34 AM vw_van_fan_Mark <madvws@cox.net> wrote:
> 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......
>
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