Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
I've had a quick look at the wiring diagram. Yuck!
There are two fuses, 3 relays, a fan delay device and inputs from a two level temperature sensor and the aircon trinary pressure switch.
First thing I'd look at is the fans themselves. They work as one and are permanently live. The relays ground them in order to switch them on.
With a bit of suitable wire ( hopefully I don't need to say this but keep long hair and loose clothing etc well out of the way ), ground the fans to the car body. It should be a brown wire you're trying to bypass. Don't ground the red wire or there'll be a bang and you'll need two new fuses. Once grounded the fans should operate at full speed. The ignition doesn't have to be on to do this as the fans are wired directly to the battery/charging circuit.
If that works ok : each fan has a resistor pack next to it which allows the fans to operate at a lower speed. This is the most likely place for your problem. Trace the wires from the fans to the resistor packs ( should be a white wire ). The other side of the resistor packs should have a light blue with white tracer wire. If you ground that wire, the fans should operate at slow speed.
Possible fault :These resistor packs have both failed ( maybe at different times and the first one wasn't noticed ) and so the fans aren't switching on at their low speed setting. I seem to recall reading that some of these resistor packs fail at the connectors - so have a good look there.
If this is the case, you could engineer a temporary workaround by bypassing the resistor packs so the fans only work at full speed. That'll at least allow you to operate the car tomorrow without damaging the engine.