Bad thermal fan clutch or faulty coolant temperature sensor switch?

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I have a Savana 3500 cutaway that I run my trailer repair service out of. I recently started having issues that I've narrowed down to either a bad fan clutch or a shorted out temp sensor switch. I had my wife start the engine while I held onto the fan to see if it had enough power that I could feel it trying to turn but felt nothing. I'm thinking it's the sensor because when I had my power outlet reel plugged in and touched the frame and the side panel at the same time, I got shocked, but not when it was unplugged. So, I think it shorted out the sensor switch. Plus, my OnStar vehicle diagnostics wasn't sensing any problems even when the engine was overheating, so maybe it did something there too. I don't want to replace parts that don't need to be replaced, can't afford to waste that kind of money. If I can't drive my truck, I can't work. If I can't work...well, fixing my truck won't be the only thing I can't afford. Please, I need help asap!

What makes this problem better or worse?

It's worse when engine gets hot

How long has your 2016 GMC Savana 3500 had this problem?

A few days

Visitor

in Middleburg FL

Jul 3, 2020

2 Replies

Popular Answer

DaveJMon Jul 3, 2020

Hello, your coolant temperature sensor has no bearing on whether the fan turns on or not. The fan clutch itself operates depending on the temperature it senses from the engine, and increases resistance as the engine comes to and exceeds operating temperature. Holding the fan while your wife starts the engine is a dangerous thing to do and doesn't prove much! Your OnStar system won't tell you anything about your mechanical fan clutch. With the engine off, your fan should rotate. It should come on and run when the engine gets between 185 - 205 degrees Fahrenheit. If when the engine is that hot it does not turn on, you have a fan clutch issue. If the fan does not rotate with the engine off and cool, you have a fan clutch issue. There is a coolant temperature sensor that feeds the gauge, and one that feeds the engine's computer. But again, neither affect fan clutch operation.

Richard 4b068don Aug 26, 2023

In vehicles with electric clutch’s for radiator fan the cooling sensor works with computer to turn clutch on or off, if fan has no play it could just be a bad cooling sensor, fan should rotate freely while off and cool by hand

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