The 'E' Type Forum

In my S1 4.2 OTS, the engine cooling doesn't come on at all. I have changed the thermostat and no change. I then checked the Otter switch wires - shorted the fan doesn't come on. So, I checked the fuses - all OK. Starting to think the fan itself may be the culprit. I plan to direct DC the fan from the batter to see if it works - Any other suggestions or ideas?
John

If you have an Ohm meter (multi meter), you could check for continuity on the fan motor.

Is there a fan relay fitted to your car (which may or may not be adjacent to the fan)? If so, it would be worth checking that out.

Hi John, I would start by finding your fan relay, mines to the side of the header tank.
Locate the fan 12v wire here, disconnect from relay and put battery 12v to it and check earth is good to the other fan wire to at least see if the fan runs with direct power. If fan doesn’t run, you need to check wiring from this point to the fan and if wiring checks out your fans probably toast (may be stuck if not used in awhile).
If the fan is good check the relay has good 12v power (permanent & Ignition) and earth connections. Mine runs with ignition 12v so the fan doesnt run the battery down with key out of ignition.
The earth comes from the otter switch which bridges to earth when it gets to it’s over temperature state, this in turn will switch the relay and bring the fan motor on. You can check this without engine being hot by putting main otter switch wire to earth and if relay has 12v in place, the fans should run. It’s quite basic once you get your head around it. If it’s not triggering at this stage but your fans running with direct power, it’s looking like a relay fault.

Here’s a basic diagram to get you started, but check all wiring in place first for usual breaks and bad earths etc. these girls aren’t getting any younger! I had a kenlowe adjustable thermostat instead of otter switch originally, now replaced with otter switch as it is simpler and more effective for my S1 requirements.