Old Library

Hi all,

It's been a long time since I've been on the list.  (Some of you may remember
me - I was an active member about a year ago.  I eventually got so fed up with
my car, I abandoned the list (and all things "VW") to pursue my dream of owning
a 911.  After many testdrives, a few loan applications, and several
unsuccessfull attempts at unloading my '95 Jetta GLX, I'm now married, and
still driving the GLX, and the wife wants a house....  Priorities......)

So, my problem last time we spoke was that my car seemed to be running really
hot.  Temperature needle creeping up, the "overheat" light coming on...  I
replaced the thermostat and radiator fan switch with the "cooler" versions, and
that suppressed the problem somewhat, but not completely.  The dealer, and
several other mechanics could not diagnose the problem.

Then, last summer, my A/C compressor started making a horrific noise.  (It was
at that point that I wanted to unload the car.)  I eventually decided to keep
the car, and at the beginning of this summer, dropped the $1400 for the new A/C
compressor.  (Damnit, that suspension will have to wait a little longer!)

Back to the overheating problem:  On a recent 9-hour road trip in 97-degree
weather, I noticed something that hadn't been apparent before.  The car ran at
normal temperature when cruising at 75mph, but when stuck in slow traffic,
that's when temps rose...  Hhhhmmm, I wonder if there's something going on with
the radiator fan.

I finally tested the fan.  It works at LO speed only.  When I jumper the
harness going to the radiator fan switch for HI speed (as instructed by the
Bentley's manual), nothing happens.  Makes sense!  The car only runs hot on 93+
-degree days, w/ the A/C on, when I'm moving slowly...  (By the way, I removed
my wiring modifications that I did when I added the cooler fan switch, just to
confirm that the problem was there before I made the modification.  It was.)

Anyway, I need to trace the wire to the "Coolant Fan Control Module" spoken of
in the manual.  The wire disappears under the battery, and I think up into the
firewall.  Anybody know where this control module is?

Second question:  There's a "Third Speed coolant fan control switch" in the
schematics as well.  Anybody know what this is about (where's it located?)?  I
was under the impression that our radiator fans only had LO and HI speeds...

Miffed:  So, why the hell, two years ago when I took my car to the dealer and
said, "it's running hot", they did a cooling system pressure test, and NOTHING
ELSE, and said, "everything's OK".  The procedure is plainly spelled out in the
manual!  ...And after running at these HIGH temperatures, I'm worried my engine
is gonna die sooner that it would have.  ...But thank God for Mobil 1!  (Oh - I
HAVE had the radiator fan recall service done. ...It was done in the winter.
...And the first time my car started running hot was the following summer...
 Coincidence?  I think not....)

Thanks for any information!

Dave
&#97;nderson&#64;msai.mea<img src=/i/dc.gif border=0 width=35 height=15>

> Subject: [gti-vr6] Radiator fan not working correctly... 
&gt; From: "David Anderson" &lt;&#97;nderson&#64;msai.mea<img src=/i/dc.gif border=0 width=35 height=15>&gt; 
> Date: Mon, 20 Jul 1998 08:44:34 -0400 
> 
> I finally tested the fan.  It works at LO speed only.  When I jumper the
> harness going to the radiator fan switch for HI speed (as instructed by the
> Bentley's manual), nothing happens.  Makes sense!  The car only runs hot on 93+
> -degree days, w/ the A/C on, when I'm moving slowly...  (By the way, I removed
> my wiring modifications that I did when I added the cooler fan switch, just to
> confirm that the problem was there before I made the modification.  It was.)

To test the fan itself, you have to apply +12 dirctly to the terminals
at the fan (which is clearly has 3-speeds).  +12 at Red/White wire
should give you Low; at the Red/Black wire, Medium; and at the red/green
wire, High.   However, it looks like the fan speed is controlled using
an built-in resistor pack, so if it works on low, chances are really
excellent that it works oh medium and high as well. 

> Anyway, I need to trace the wire to the "Coolant Fan Control Module" spoken of
> in the manual.  The wire disappears under the battery, and I think up into the
> firewall.  Anybody know where this control module is?

No, I don't.  Two locations come to mind:  In the cabin, on or near the
relay panel, or, more likely under the coolant resivoir tank.
(Schematics for later cars indicate its "In left side of engine
compartment).

> Second question:  There's a "Third Speed coolant fan control switch" in the
> schematics as well.  Anybody know what this is about (where's it located?)?  I
> was under the impression that our radiator fans only had LO and HI speeds...

Hmm.  Again, the schematics for the 95s don't give a clue, but
schematics for the later cars do say "In Center of Engine Compartment". 
However, later cars have a different part (4 leads instead of 2), and
I'll be darned if I can actually find it.  

Anyway, it *is* a three speed fan.  Low, Medium, and High.  When mine
(97, slightly different electrics) kicks into High, it's *really*
obnoxiously loud (doesn't usually happen unless I run the A/C).   
 
Since you have a 1995 and all this stuff is out of warranty, one
expedient way to solve the problem would be to jury rig an override so
you can manually run the fan on high-speed whenever you feel you need
it.  Get a 30A relay from Radio Shack, splice it in between the battery
and the red/green wire to the fan, and mount a switch that controls the
relay someplace in the cabin...
I had a manual override like this in my '84 (long story).   

-Uwe-

On Jul 20, 11:19am, Uwe Ross wrote:

> To test the fan itself, you have to apply +12 dirctly to the terminals
> at the fan (which is clearly has 3-speeds).  +12 at Red/White wire
> should give you Low; at the Red/Black wire, Medium; and at the red/green
> wire, High.   However, it looks like the fan speed is controlled using
> an built-in resistor pack, so if it works on low, chances are really
> excellent that it works oh medium and high as well.

Yeah - studying the schematic, it looks as if, if it runs on LO, it will
DEFINITLEY run on the other 2 speeds.  (Unless, of course, one of the pins in
the harness connector is broken off.  It's a possibility!)


> > Anyway, I need to trace the wire to the "Coolant Fan Control Module" spoken of
> > in the manual.  The wire disappears under the battery, and I think up into the
> > firewall.  Anybody know where this control module is?
>
> No, I don't.  Two locations come to mind:  In the cabin, on or near the
> relay panel, or, more likely under the coolant resivoir tank.
> (Schematics for later cars indicate its "In left side of engine
> compartment).

ANSWERING MY OWN QUESTION:  I finally decided to call the VW dealer (they're
NEVER helpfull).  They surprised me this time!  The service manager actually
told me where the radiator fan control module is:  under the coolant expansion
tank.  I went out to my car and looked. THERE IT IS!


> > Second question:  There's a "Third Speed coolant fan control switch" in the
> > schematics as well.  Anybody know what this is about (where's it located?)?  I
> > was under the impression that our radiator fans only had LO and HI speeds...
>
> Hmm.  Again, the schematics for the 95s don't give a clue, but
> schematics for the later cars do say "In Center of Engine Compartment".
> However, later cars have a different part (4 leads instead of 2), and
> I'll be darned if I can actually find it.

I now believe this is the same as the "A/C Thermal Switch", located in the
thermostat housing, right next to the Temp-Sensor and After-Run Switch.  (My
manual has it in the "A/C" section:  "A/C Thermal Switch - Only on vehicles
equipped with VR6 engine - Swithces coolant fan to third speed when engine
coolant temperature increases".

Anyway, thanks for your input!  It is indeed a 3-speed fan.  I will test it
tonight, to make sure all 3 speeds work (I'm sure they will) and make sure
there's continuity to the Radiator Fan Control Module.  At that point, I'll
probably have to go to the dealer and say, "Sell me a Radiator Fan Control
Module.  Here's my wallet.  Now wait while I bend over....."  (Sorry - I'm
bitter.)

Dave
&#97;nderson&#64;msai.mea<img src=/i/dc.gif border=0 width=35 height=15>