The Stovebolt Site Forums The Shop Area The Electrical Bay Fan Override Switch

I'd like to run the by you guys before proceeding. I have an electrical fan that is thermostatically controlled and fed through a relay. The thermostat completes the ground to trigger the relay. Works fine. Can I add an override switch with one side going to ground and the other side tie into the switched ground running from the thermostat to the relay?

I'm using Painless Fan Relay part# 30129

Dennis

Yes, but be sure to carry a good set of jumper cables at all times.
Jerry

Thanks for confirming that HR. Yeah, always run the risk of forgetting to turn it off but it is kind of noisy when the engine is off.

Dennis

Yes you can..... but:
1. Wire it so that ignition switch will turn off fan feed.
2. You won't have a fan cool down after motor is off.
3. Why do you need to do this?
4.Do you want to have the sensor still work and your new switch?

You can connect the two wires at the sensor together. No extra switch necessary. But it will be on all the time ignition is on.

Isn't an electric fan a solution looking for a problem?
Jerry

OK, you guys talked me out of it. I just wanted an option of turning it on early if I thought I was going to be taxing the cooling system so could get it a bit lower than normal early on. But I doubt I'll see that with the truck. I've rarely had the electric fan turn on. It is a supplemental to the engine fan added when I put on A/C.

Dennis

I run that setup in my daily driver, I thought I'd need the bypass more for plowing snow but the engine rarely gets that hot, the racing fan that's in there (I forget the brand) handles it well with the little shroud the electric fan came with. Moves a lot of air. I ditched the clutch fan on it probably 13-14 years ago and it works fine with a thermostatic switch (OT but a 5.0). Rarely, with heavy wet and deep snow, I've turned it on manually but mainly as a precaution.

The fan is wired to ignition, so forgetting it flipped on is not an issue - but in the past I have tried it off constant 12V and although with a good battery that was usually not a problem, they do drain the battery pretty quick if you accidentally leave it on.... don't ask me how I found that out.

In my 49 3600 last year I swapped in an EFI (TBI) 4.3 and for many reasons of my own I set the engine ahead and for fan clearance reasons I opted to run an electric fan off a thermostatic switch. I could have fit a slim fan in there, but... given my experiences in my daily driver I just ran the electric fan. I didn't get it finished until later in the summer so haven't tried it in the heat yet, but drive it a lot in the late summer/early fall so far if anything it's running cooler than I'd prefer. Rad size is obviously a factor there.

I didn't bother with the bypass switch in the 49 after seeing how well the thermostatic switch worked in my daily though.

Yep, those four 1200 HP Wright Cyclone electric fan motors on Dad's B-17 helped win WW II!
Jerry

My electric fan has the thermostat switch and a manual over-ride that is turned of when the ignition is off.