Fan runs with heat on

[Joshua Van Tol]

On Thursday, January 9, 2003, at 03:13  AM, Navistrpwr at aol.com wrote:

> heater on my brother's 5k.  One thing I noticed is that the 1st stage
> cooling
> fan always runs with the climate control on, regardless of whether or
> not
> it's set at 60 F or 90 F.  This isn't normal, is it?  I'd say it
> isn't, as
> the engine never warms up sufficiently with the climate control on.  I
> talked
> w/ the parts guy at my local Audi dealer and he said that the system is
> getting an A/C signal somehow.  He pointed to the A/C control head
> and/or the
> temp sensor on the evaporator housing as the culprit.  I've replaced
> the
> programmer, control head, and temp sensor with units I got at the
> junkyard to
> no avail.  I replaced the radiator fan control switch with a brand new
> one
> (and am glad that I did so...I didn't realize the 2nd speed fan was
> malfunctioning, it would always run at high speed...fixed that
> problem)  I
> also tried disconnecting the high pressure switch on the condensor to
> see if
> that would be causing any problems.  I'm at a loss for what else to
> try.  The
> only way I can get the fan to shut off is to remove the 1st speed
> relay in
> the fuse box under the hood.  However, I put it back in so the
> after-run fan
> will still work.  Any ideas as to why this fan constantly runs?
>
What's the outside temperature when this happens, and are you in "econ"
or "auto"? In Auto, the fan runs, because the ac clutch could become
active. I don't remember  if it cuts off when the temperatures are too
cold, but it may. Try putting it in econ and see if it still has this
problem. Also, have you checked the heater valve, and whether the
heater core is plugged up? Finally, you should probably see if when the
heat is on "hi" the motor in the programmer drives the bowden cable all
the way to the hot stop.