So... I have a problem with my cooling fans.

They appear not to work at the slower speed but only - and for brief periods - at the higher speed. The leads to the engine temperature rising above an indicated "normal" prompting the high-speed fan operation to kick in. (This only happens when the engine is hot and I pull over, say into a car park - or, of course, in stop-start traffic.)

The official wiring mod at connector PI102 seems to have been made. Both 30amp fuses at locations 11 and 17 are ok.

My understanding is that, with the mod in place, the fans should run continuously when the A/C is on (I always have it turned on). I wonder whether it could be a problem with the relay mounted in the bumper?

Any helpful suggestions would be warmly (no pun intended!) welcomed!

 

If the wire loop is installed in place of the pressure switch, then the fans run WHENEVER the Key is ON (position II).

bob

 

So your fans don't run when you switch on the ignition before starting the engine? They do in my car.
In low-speed the fans are in series so if one goes open-circuit neither will run. In high-speed they are in parallel so if one is faulty the other will still run.
When the engine gets hot and fans run at high speed, do both run or just one?

 

1. They don't run when I switch on the ignition
2. When the engine gets hot BOTH run.

Any more thoughts?! :-)

 

Firstly, you are fortunate that both fans coming on "High" from off hasn't blown your fuses. But keep a sharp eye on 'em...may happen eventually. If you have the wire-loop mod, then your fans should run on low-speed all the time the key is on, as Bob mentioned. I would start the troubleshooting with everything in the low-speed circuit. It's foggy now, but when I had the a/c switch failure and had to effect the wire loop mod, I seem to recall there is a temp at which the radiator switch commands the fans to low speed (but I may be totally wrong about this - as the fans now run full-time irrespective of radiator temp) and then a higher temp that it commands hi speed. Not sure, but I imagine if the low-side of that switch fails "open" then your fans won't run on low. The other likely failure of the low-speed circuit is the low-pressure switch in the A/C high-side line that is bypassed by the wire loop mod. I presume that is what you mean by, "The official wiring mod at connector PI102 seems to have been made."

 

Please read through the TSBs and understand how the system works.

bob

 

Andy,
Having read the thread so far, a couple of thoughts occur to me.
The fans serve two purposes, to dissipate heat generated by the engine, which manifests itself in the radiator/ water coolant, and to dissipate heat generated by the aircon, which manifests itself in the condenser, refrigerant.
Dealing firstly with the aircon, there was originally a switch which controlled the operation of the fans, but early on in the production run, the terminals on it were shorted by a piece of wire so that the low speed fans would work whenever the ignition was switched on. As has been mentioned above, the little loop of wire is easily visible at the bulkhead, so you should easily be able to tell whether your car should have the fans come on when you turn on the ignition. One qualification to that comment relates to a modification described elsewhere on here which takes a feed from the aircon compressor clutch relay to a relay wired into then fan control circuit. This has the effect of ensuring that the fans only run when the compressor clutch is engaged, and is a mod which I have fitted to my car, as here in the UK, the compressor doesnt need to run every day! The relevance to your current situation is that you would need to turn the aircon right down and start the engine to be absolutely sure that your fans should be running in low speed.
From what you have said about your water temperature reading, it seems much more likely that the demand for the fans to operate is being generated by the engine rather than the aircon, and for this purpose, the fan actuation is controlled by the sensor at the bottom lefthand side of the radiator. As you have said your fuses and relays are ok, I would have a look there. Whilst there could be a fault with the low speed on each of your fans, it is unlikely they would both depart at the same time ( although one could have packed in a while ago, and you only noticed when the second one went, I suppose)
Try disconnection the fan wiring harness and using a live feed to establish that the fans will work in low speed.