Recently the cooling fans turns on as soon as I start the car. The fans run as long as the car is on. The fans after a few minutes will just turn on sometimes if I leave the key in the auxiliary position with the engine off. Had been running fine for years…
Check your otter switch first. Unlkely to be fan relay but that would be second place to check.
I disconnected the otter switch and the fan still came on. I’m thinking the relay…
Thanks for the input.
The otter switch will connect terminal W1 of the fan relay to ground/body, initializing the relay at the appropriate temp. Check to make sure there is no stray ground at W1 (I think this is the black-red wire)
if you disconnect this wire, the fan should never come on as the relay coil can’t be activated. If it does, then it may be the relay.
Since the ignition switch only provides power to the relay, but does not activate the relay, it is not your ignition switch. Unless, of course, someone has re-wired the fan circuit in a non-standard configuration.
Many E-Types were modified by prior owners or their shops to have the cooling fans on whenever the ignition switch is in the ON or accessory position. I recommend that you trace the wiring and make sure that it is the correct factory configuration for your car which varied from year to year and depends on whether or not your car was equipped with factory air conditioning. Look for any unusual colored wires or crimped connectors as a sign that the wiring was modified.
As already mentioned you need a good wiring diagram for the specific configuration of your car for this project as well as other issues/questions that will come up in the future.
As Paul just mentioned, if you have factory A/C (or used to have it, and the wiring is still in place) things get more complicated. Please let us know if this is the case, as many of the comments to date assume that you do not.
yes I do have factory air conditioning and it still works!
If the ac switch is on, the fans will run continuously.
Another common problem is the wrong thermostat. The early S2’s came with a 76c thermostat and an 85c otter. Notice that the thermostat set point is lower than the otter. If you install an 82c thermostat, the fans will run almost all the time.