I currently have my fan wired so that I turn it on with a toggle switch. I want to wire in a thermo switch and retain the toggle in case I need it. I was told to use a switch to the 12v side not the ground side. The thermo switch operates to the ground side. The thermo switch is designed to switch to ground. So,I don't see a problem with rewiring the toggle switch to be in parallel with the thermo to ground. Anybody think that this is bad? Thanks, Bill
should not be a problem. I do suggest having the thermo switch and toggle switch activate a relay, and the relay activate the fan, so the switches last longer, and it could make the fan work better too by cutting down high current wire lengths.
squirrel is right, because if you add the temp switch and the plus side is to battery the fan will run untill the engine cools below the lower switch limit. Use a relay that is powered only in the run position and run the battery to the load contacts, that saves the load on the ignition switch. You still can run the toggle switch to the relay also. And add a circuit breaker to the battery feed to the relay.
The toggle switch goes to a relay that activates the fan. I just left that out of my question. Thanks for the responses. Bill