Lotus Elan and Lotus Elan Plus 2 Forums

Having acquired my S4 in boxesa coupke of years ago, I've just fitted the loom back, but there's a bit of a quandary as to where the live feed is meant to come from to feed the electric rad fan motor thermostatic switch. Can anyone please advise .
Thanks, Pete

I don't believe the origional loom had an electric fan feed. I fitted an electric fan on my S4 that I powered off of the starter solenoid to a second fuse block. Power goes from the fuse block to a relay and then to the fan. The thermostatic switch on the radiator opens the ground from the relay control voltage to turn on the relay.
Specifically, on my relay, pin 30 is 12v source and pin 87 goes to fan +, the load. Pin 86 is the relay coil + feed, and pin 85 is the relay coil ground which goes first to one side of the radiator thermostatic switch and then from the other side to ground. When the thermo switch trips it opens the relay coil circuit which sends power through the relay to the fan motor.
Most seem to want unswithed power from the battery, brown wire, so the fan can continue running if the coolant is still hot after the ignition is switched off.
On my car I also wired in a switch to turn on the fan manually, and a light to indicate the fan is running.

Thanks for your response, this is a good option in the event I cant establish how it was originally set up.
This is a very late S4 and has the electric fan mounted to the rad as per a Sprint. The thermostatic switch is the threaded screw in type mounted at the top of the rad, on the carb side of the engine bay. All this is original equipment as is the loom and if possible, I would like to keep the car absolutely standard.
Thanks, Pete

When I did my Sprint it is just Green power from heater switch and Green/Yellow back to slow position on the heater switch

Dave

Pete, my experience has been limited to the S2 & S4 which is why I said "I don't believe...". I've seen fans but didn't know they were stock in the Sprint so I learned something today. I probably should have researched it more and installed mine as Dave suggested.
Cheers, Victor

When I acquired it back in '83, my S4 was unmolested - the feed to the thermostatic switch in the radiator was a separate green wire from the fusebox, clipped to to the battery cable and then routed under the carburettors. Definitely not part of the wiring loom. I'm convinced that's how it came from the factory.

Nigel F.

I don't remember now how the fan was wired with the original harness but I do know that my S4 came from the factory with the fan as standard. I did not need to add any additional wiring. Installed new harness when I rebuilt the car a few years ago & the wiring for the fan was part of the harness.

A manual switch for the fan is a useful addition ...

Carl