nigelhenry

Hey guys,

My rh front radiator fans appears to not be running, anyone know if these things run on a thermostat?

Cheers...

jpflip

I am looking at the wiring diagram and can see only one temperature sensor on the engine. This sensor is located on one of the coolant pipe,elbow, just beside the belt tensioner (same one used for temp indication). According to the wiring diagram this sensor send a signal to the DME (ECU) and the signal goes to a set of three relays per fan. One relay for each phase and each fan has three phases (total of 6 relays)…Durametric can test the fan and also the phases. You should look at the fan electrical connector and also try to jump it directly to the battery… There are four wires on this connector. One ground and one for each phase….

Macster

They are controlled by the DME based on coolant temperature.

My experience is the fans come on seldom as it takes considerable slow speed driving for the engine to get hot enough for the fans to come on.

With the car moving even in high temperatures air flow through the radiator ducts -- courtesy of an extremely efficient aerodynamic design -- is sufficient to control coolant temperature without the need for fans.

(Unlike my Boxster which can even at highway speeds in high ambient temperature require the fans be on high speed to control coolant temperature. The Turbo's cooling system efficiency is very impressive.)

However fan motors have been know to fail. I myself have had two go bad. The first one suffered a snapped shaft (the tech said he had never seen one fail like this before). The second just quit running.

A quick and dirty test is to turn on the A/C. This should have the fans on. Both should be running and both should be blowing the same amount of air out from the vents in the wheel well.

A more involved test would be to drive the car around town confining your driving to streets with a limit of 35mp or less until the engine is quite warm.

Then back at home in your driveway raising RPMs to say 1500 and holding RPMs there until a helper detects at least one fan coming on.

At this point you can then let RPMS return to idle and get out and check fan operation.

Another way involves hooking up the Porsche diagnostic test computer and checking for any fan stage errors and possible manually controlling the fan operation and speed. The tech can also check for how much current the fan motor requires which can point to a problem with the fan motor.

nigelhenry

Thanks for the replys, front left runs continously but think the right has failed.
Hopefully not toooo expensive.....

fly2low

Fans are about $450
The fan for a non turbo 996 is about half of that, but is 2 speed instead of three
you can transplant the ballast/resistor from your old fan to the new fan - which is what I did
It is a DIY if you are inclined

info on the fans is posted in this forum somewhere but could not find it with a quick search

rmc1148

You could check connector at fan with test light and aslo apply juice and see if it runs.

fly2low

I would take the fan failure as an excuse to replace the radiators
and I would do both fans - especially if you are paying someone to do this

nigelhenry

Thanks for the good suggestions.

Macster

The bad fan from my Turbo ran when tested this way after it was out of the car, but the fan was still bad. It was drawing too much current and was not running like the other fan or the new fan once the new fan was installed.

rmc1148

Yes I have seen that before but is rare, usually can feel some rough spots/resistance when you spin it by hand. Depending on miles/age if they give me problems and they are getting juice I just replace. On my A4 I was having problems with fan not cooling well enough for a/c to work properly, with new fan a/c nice and cool now.

nigelhenry

In an attempt to see what was is happening in there, I took off the RH front wheel and removed the wheel arch liner which gave a look at the fan, it doesnt spin freely and i think it needs to cone out.

Is the best way to remove it from the wheel well (behind) or remove the front bumper and radiator ang get it out that way?

Cheers..

fly2low

Mine were replaced with the radiators, so my route was from the front. The fans are mounted in shrouds, which in turn are mounted to the back of the radiators. One end has tabs, the other has screws/bolts (don't remember which). If the end you are looking at has the bolts/screws, you might get them out without removing the radiators. If they are on the far end, doubt you can get the out without removing the radiators