Date: Thu, 24 Sep 1998 09:08:54 -0700

["Rich Lasner" <rlasner@xxxxxxxxxxxxxxxxxx>]

In V7 #126, Mike Israel writes: "The cooling fan on my '91 164S no longer
turns on.  I have also noted that the temp light comes on frequently even
when engine is stone cold.
I checked the 40 amp fuse strip.  Any suggestions on what to look at next
and/or how to check whatever I should be checking?"
Mike- You have two separate systems at work here. The system that starts the
fan is connected to an air temp. sensor in the fan shroud that sends signals
to two relays- one for the low fan speed, the other for the high fan speed.
These relays are under the second black plastic cover from the right when
looking into the engine bay from the front of the car. You've already found
the 40 amp fuse strip on the firewall. All of these parts are perishable and
had to be replaced in my 164S. See if the low speed fan comes on when you
turn on the air conditioning.  That might help you determine if the low
speed fan relay is working.
The temperature gauge and overheat warning light are connected to a sensor
that sits in the water pump on the belt side of your engine. If the ground
is bad, or the contacts are corroded, you can get the kind of readings
you're talking about. Try taking the part out and cleaning it, then check
the contacts and clean with DeOxit or similar contact cleaner. I finally
replaced mine to stop the red light from coming on, but the new sensor reads
20F higher than the old one did.

Rich Lasner
Mill Valley CA
92 164S (90k miles, daily driver)

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