Has anyone ever wired up an electrical fan with a temp sensor and also hooked up a manual override switch to it? I have a Derale adjustable electric fan controller. I am trying to wire in a switch and relay so that I can turn on the fan at will, while still keeping the original function of the Derale fan control.

66 600hp Malibu
Dart Pro 1's

2 wrongs don't make a right but 3 lefts do graemlins/beers.gif

Search through the heating and Cooling forum. Adding electric fans has been discussed there many times. I'm sure you will see what you need.

Yep, I've done it - I'll get back to you ASAP with a diagram of some sort.

I used a permacool thermostat, and it had one nice feature, a signal wire meant to turn the fans on when the ac is on. I just used the thermstat normally, for thermo controlled fans, and I have a switch to apply 12v to the signal wire too, and that forces the fans on, regardless of temp. I think a signal wire meant to turn fans on when using AC is common, maybe your thermostat has that feature as well? I have a wiring diagram of my setup if you are interested.

chris