Different kind of fan control question than usual.

Before my old engine died, I had MS controlling the fan for my 1.6L and it worked just fine. I'm sure the MS worked as I tested it by temporarily setting the fan on to a much lower temp than the front thermosensor to see if the fan would kick on. With the new engine, I did a coolant reroute and removed the thermosensor for the fans at the top of the thermostat housing thinking that since I was using MS to control the fans, I didn't really need it. I did leave the ECU wiring harness to the thermosensor intact, just removed the sensor/front thermostat housing.

Now my MS fan control does not work. So, I'm thinking that my MS fan control must have been thru the thermosensor loop and that's why it does not work now? If I just connect the two thermosensor harness wires, will it work fine or will the fans just run all the time? Or am I missing something else? I'm asking before I go hacking into the harnesses.

 

so are you planning on dynoing your car tomorrow with no fans? i'm glad i'll be there.

Bruce, better bring that cherry picker back...

 

Worst comes to worst, I'll ground out the harness and keep the fans on constantly while I'm on the dyno. Plus, tomorrow is going to be cold.

 

The front switch on the t/stat housing is one wire that goes to ground when the temperature is reached. Shouldn't have two wires.

 

Correct, just went out to the garage to track down the harness and found the one black wire.

 

You have one of Brainy's parallel jobs? It might rely on the stock ecu and thermosensor to control the fans.

If it does control the fans directly, the fan on point setting is kind of weird. You have to enter in your desired on point temperature in degrees F-40. Meaning if you want the fan to come on at coolant temp 200F, you enter in 160. It's labeled next to the box where you input the setting, but it's weird and easy to miss.

 

i thought the fans worked without the ecu. when the thermosensor grounds it activates the +12v switch in the cooling fan relay.

so to make the fans work you just gotta put the MS to 1R.