UK Car Repair: 1992 VW g60 Corrdo radiator fan, last ditch effort, thermal resistor

Question
Hi. Having spent the last 5 months restoring a Poorley G60 Corrado I find I'm heading for the MOT this coming week. One problem for the life of me I am unable to get the radiator fan to work. I have bought a genuine VW rad switch and a local shop bought version. Neithr work. I have tested the circuit by shorting the fan switch connection by using a length of cable and placing it in the middle terminal then using the other end to bridge the other two terminals. 1 terminal for low speed and other for high. The fan ran perfectley on both speeds. I refit the 2nd new switch get the car up to temp and again no fan. I don't know hat else to do. It refuses to come on as the engine needs it. I have no cooling. These cars run to hot esp with the supercharger. Can you help. Some have said just put it on a dash switch?

Answer
Your car has a separate cooling fan sensor and relay. It is designed to open and close the relay at certain temps. A thermal resistor takes car of high low speed. I have a feeling the block mounted switch is what you were referring to me for info on.

Airtex part # 1S4350
95C on 87C duel thermal.

Go to this address, http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=ECH&Par...

If this is the switch and you have not been able to get it to work, I suggest you take the harness end off and clean it really well. Try squeezing the metal bits inside the connector with pliers to tighten up the connection. Also, try hooking a bit of grounding wire to the brass part of the sensor when it's hot to see if that works. Last ditch effort, bleed the cooling system. Take the highest hose off "usually one of the heater core lines at the block" unscrew the cap on your coolant canister and hook a hose with a funnel to the tit where the heater core line went. Fill it from the top and see if you get any air pockets that relieve themselves. Another more dangerous method would be to use a large towel folded twice over or more and lay it on top of the canister and when the vehicle is hot... crack it open for a few seconds till you hear that it's going to boil out and then shut it. The surge can sometimes loosen air bubbles in the system. If that still doesn't work, then, move on to the dash switch. Only for a temporary solution.
The problem is localized to the switch. You can test around the switch and it works. So, you have your problem. You even know that a reasonably good connection at the plug will activate the fan... So, I would not worry. You know where it is. If the switch won't work... try getting a new plug and splicing it on to see if that takes car of it. No biggie. Just let me know how you make out and we'll take it from that point on.  

Happy Motoring

John