m20 sensor in the radiator on pass side?

[Kozworth]

I don't have a bentley yet but was just wondering what this sensor was for. I am getting weird temp reading issues and the wires are frayed on this sensor. Thanks

[KenC]

Fan switch.

[browntown]

I'm working from old man memory, but I'm fairly sure that sensor determines when your aux fan goes on/off. There is an upgrade from a e36 318 I think that allows removing your mechanical fan.

None of this is fact, just shaky memories. search around.

[Kozworth]

So the aux fan just kicks on whenever? I used to have if id idle too long the temp gauge would rise.

Anyone have a wiring diagram or know which wires are power/ground? I want to test the switch

[KenC]

It's a mechanical thermal switch. One pole is constant power, one controls low speed, and the other high speed. Just hook it up to test it. It controls the front aux fan.

[Kozworth]

Is there a way I can test with a multimeter for continuity? that's why I wanted to know which wire was power/ground

[KenC]

I don't think so. I tried to test it before I hooked an electric radiator fan into it. All the posts are power. Its a mechanical thermal switch.

[Kozworth]

Its probably a thermister self generating voltage input and grounded by the computer. Got a new sensor but the wires are spliced right at the female plug housing. Is there any thing I can do besides buying another and splicing it? I didn't see a replacement off german auto parts.com

[KenC]

I'd just snip one at a junkyard.

[Kozworth]

II read that if there is overheating issues with ac off it is not related to the aux fan. I don't even have a belt on the compressor so would this be not worthwhile to figuring my overheating issue out?

[jlevie]

Overheating with the A/C not running indicates that there is a problem in the cooling system. If the overheats only happen when the engine is idling the cause may be a bad fan clutch (or missing blades of the fan). But that can also be caused by a partially plugged radiator, a bad thermostat, or a bad water pump. Overheats at speed will the the thermostat, radiator, or pump.

[Kozworth]

Could air in the system cause performance issues? im getting sputtering sometimes.. and a loss of power. The car does not overheat but still think there's air since I don't have any heat.

New tstat, wpump, new coolant.