Radiator Fan Relay Contact Welding (w/70amp relay!)

["Douglas H. Quebbeman" <dougq@iglou.com>]

Not too long ago, someone mentioned (I'm not sure the issue had its
own thread or not) how the contacts in the 30amp radiator fan relay
can weld together (I think the 5ktq's were the subject auto). This
must have happened to my 5ktq sometime in the past; the relay had
been replaced with a 70amp unit, and the original high-current supply
wire (the large-guage red one) had gotten hot enough to melt together 
with some its neighbors in the wiring harness.

Also, while the turbo cooling pump circuit still works, but the fan
doesn't kick on at a low speed like it should; I haven't yet located
the step-down resistors for the fan; they may be shot or or even 
missing.

A new supply wire was put in place running to the relay.

In spite of this, while leaving the drive-thru at Hardy's, the
fan did not shut off when I expected it to. I got back to the
office, shut off the car, and the fan was still running (again,
I need to mention that none of the afterrun circuitry has ever
triggered the fan as long as I've had the car). Popped the rear
seat, disconnected the battery ground. Removed the relay, and 
while the contacts were no longer stuck together, the contact
surfaces had the same crystalline appearance you'd see in a cold
solder joint. I filed the relay contacts down a bit, replaced it,
reconnected the battery, and have had no repeat since.

The temp guage on my 5ktq rarely goes past the middle position;
however, I've been getting overheat alarms from the computer.
Suspecting a problem with the coolant level switch (which sets
the same alarm), I disconnected it, and the alarms went away.
And whenever I check the coolant level, it's OK. 

As usual, I'd appreciate any hints, suggestions, or BTDTs, and TIA!

--
-Douglas Hurst Quebbeman (dougq@iglou.com)
--
Current AUDIs:
74 100LS Automatic w/Weber 32DGV (in storage awaiting restoration) [#01]
77 100LS Automatic (in driveway, rusting)                          [#06]
84 Coupe GT (Running since Jan. '97 w/dry 5sp transmission)        [#07]
86 5KCSTQ (Finally, a Quattro!)                                    [#08]
--
"The large print giveth, and the small print taketh away."  -Tom Waits