[s-cars] 93 urS4: high speed fan and AC questions

[Paul Gailus]

If the AC condenser is not getting enough cooling air, the
high-side pressure can increase enough to trigger the high
pressure limit switch and shut off the compressor. So this
could be causing the on-off AC cycling that you're seeing.

Does the fan at least run at a lower speed? I had a problem with
the connector at the end of the fan hot lead being corroded/dirty
so that it wouldn't run at all. The connector was kind of a pain to
get at, nearly buried under the intercooler outlet fitting. But after
pulling this connector, some minimal cleanup, and reconnecting
it I've had no problems.

If it's just a problem with the high speed fan mode, I would pull
the connector from the lower radiator temp switch that you mentioned.
With the ignition switch on (engine not running) you can then
jumper this connector to test out both the medium and high
speed fan operation. If the high speed kicks in, then
it's likely that the temp switch is causing your problem.

Paul


----- Original Message -----
From: Martin, Gary G <MartinGG at aetna.com>
To: AUDI S Cars Discussion List <s-car-list at audifans.com>
Sent: Monday, September 16, 2002 9:57 PM
Subject: RE: [s-cars] 93 urS4: high speed fan and AC questions


> What is your temperature gauge doing? I know for a fact that if the
coolant
> temp gets high enough, the AC will shut down. My problem was related to a
> failed fan resistor block, which controls fan speed. Acted just as your
> symptoms indicate. I don't remember if the fan came on at low speed, but
in
> stop and go traffic, temp went up, AC shutdown.
>
> Gary
> 94 UrS4
> 91 200 TQA
>
> -----Original Message-----
> From: Eric Billing [mailto:eric.billing at eds.com]
> Sent: Monday, September 16, 2002 10:37 PM
> To: S-Car-list
> Subject: [s-cars] 93 urS4: high speed fan and AC questions
>
>
> Thinking two separate problems here... but thought I'd ask anyway.
>
> 1) during recent heat wave here in Mpls (95+ on 9/7) I noticed that the
high
> speed fan never came on. Waited about 10 minutes to get through a Dairy
> Queen drive through on this hot day... still no high speed fan.  At home I
> did a comparo with the wagon, just idling... about 10 minutes and the
> wagon's fan goes high speed. Swapped relays with the wagon---which seemed
to
> confirm that this was not the problem. Earlier this spring, the wagons fan
> was "stuck" on high speed all the time. New switch (lower driver side of
> radiator) cured that. Me thinks the same switch is bad on the S4-only this
> time its stuck on off vs. on. Make sense?
>
> 2) Also on the S4, I've noticed a few times during very hot days that the
AC
> just doesn't cool well. In stop and go traffic, I've noticed it shutting
> itself down---even the icicle symbol on the control unit turns off and on
by
> itself. These cycles last 10-15 seconds or longer. When back to highway
> speeds, the auto off/on cycling goes away and it appears that things are
> acting normally---however, I must admit that overall cooling is lacking.
> Then again, I have a black interior on the S4, where the wagon is grey...
>
> So, independent or related? If the high speed fan never comes on, does the
> AC have some sort of auto shutdown mode to avoid excessive load?
>
> Thanks in advance for your ideas.
>
>
> Eric
>
>
> --
>
> Eric Billing
> Eagan, MN 55123
>
> 1993 100csqw
> 1993 urS4