Triumph Repair: 1980 Triumph Spitfire, electric cooling fan, temperature gauge

Question
I recently acquired my 1980 Spitfire from my father-in-law who bought it new.  The car is all original and in excellent condition for a car 26 years old.  The problem I have is with the electric cooling fan.  I had to run a manual switch so I can turn the fan on when it starts getting too hot which is anytime I drive in stop or go traffic.  The fan, once switched on, cools the car down to about 30% on the temperature gauge but I would like it to come on automatically instead of me having to switch it on and off.  I replaced the sensor in the top of the radiator but no change in operation.  I have a shop manual but it doesn't show the electrical circuit or even the electric fan.  Any light you can shed on this problem is appreciated!

George

Answer
George,

From what little info I can find on the '79/'80 cars the sensor switch on the radiator should supply power to the fan when the temperature hits it's limit.  

If it's not working then it means that either a) the new switch is bad (possible, but not 100%) or b) the wiring to the switch or the wiring between the switch and fan are bad.

The first thing to do would be to determine which side of the switch feeds the fan and see if the other lead is hot with the ignition on.  If not then it's time to make sense of the wiring harness.


Cheers,

Jim