Slipstream - September 2008

996 Water Cooling System R & R
By Chuck Freeman
If you live in north Texas the weather will eventually
get hot. With increased heat comes an increased
cooling demand on my 2000 996. About two months
ago I noticed the temperature gauge slowly creep up when
sitting at a light. I have one particularly long traffic light on
my commute that will sometimes run through three cycles
before I get through it. Sitting at this light concerns me.
Usually the temperature gauge reads to the left side of the 0
on 180. At the light it may go to the right side of the 0.
I did some research on the internet and found a site with
good information: www. renntech.org. On this site I found a
common problem to be debris that builds up between the air
conditioning condenser and the engine radiator. After linking
to some other sites on this topic I performed this task on
my own car. To do so you must remove the front bumper,
the inner fender panels and some underbody panels. Plastic
rivets and nuts are used extensively in these locations. So I
purchased extras from the dealer since they are quite inexpensive
and easy to tear apart.
Getting to the radiators is not a tough job. Just jack the
car up, remove the front wheels, and then the body panels.
It is fairly easy to figure out what you must remove to get
the panels off. Once that is done remove the A/C condenser
and begin the cleaning process. I was really amazed at the
amount of dirt and debris that was wedged in there. I have a
small pile worth of this stuff. Also, I found that there was a
lot of road tar between the
radiator fins so I worked a
stiff plastic tool in there to
scrape this material clear.
I also gave the radiators
a thorough rinsing with a
hose and let it dry.
So everything was
buttoned up and back
on the road. However, I
noticed no change in the
temperature readings. On
one particularly warm day
I got out of the car to check
the radiator fans were
turning. The passenger side
was spinning away since I
could feel the suction with
my hand. I felt nothing
from the driver’s side.
More internet
searching led me to check
the fuses (DUH) and the
Photo by Chuck Freeman
relays. The fuse for the driver’s side fan was blown. So I
replaced it and it burned out again. There are four relays for
the fans. One relay is for slow speed and another for fast
speed per each side. Since I knew one fan was working I
swapped the driver and passenger relays. The passenger side
still worked but driver’s side did not. It is my understanding
that the low speed fan comes on at engine temperatures less
than 100F and with no A/C on. At temperatures above that,
and with A/C on, the high speed fans run. There is a very
loud roar from the high speed fans so it is easy to tell if they
are on.
Since the relays were okay my next thought would be
the ballast attached to the fan. If you crawl under the front
of the car there is a metal round tube that is the ballast for
the radiator. I figured this was out so I replaced it for a part
cost of $90. Still the fan didn’t work and I got burned from
grabbing the ballast when the car was running. After the
car shut off, and was cool, I reached under the car into an
air intake duct and could spin the passenger side fan. The
driver’s side would not spin so my problem turned out to be
the fan itself was burned out. After spending so much time
working on the car myself I decided to take it to the dealer
to get fixed for $350. Now both fans run but the temperatures
still creep up a little bit. That may be normal.
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