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Cooling fan, and temp guage

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2014 sierra slt 5.3L.

I just replaced my thermostat and sensor. My fan continues to run shortly after startup and shut down. My temperature guage reads 0 or stays at 160. I'm blowing mild heat in the cab but doesn't fully get hot. Any thoughts? 



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  • 3 months later...

I was having a similar issue and currently has me stuck.  I was seeing around 180 degrees in the dead of cold we had last month.  I replaced the thermostat with a Napa brand, but it was stuck closed....replaced it with another aftermarket unit from another store, it was very slow to open.  At least it was warm in the truck, and the gauge was reading 210...Then noticed fans were noisier than usual...Connected the gm scanner and noticed the temp sensor was reading 220-230.  I knew high-speed fans would kick on at 233 degrees.  I checked the top of the t-stat housing, which was hot, but the upper rad hose was cold.  So replaced another t-stat.  The upper hose gets hot as it should, which tells me it is opening at least, however, the fans will run as they should sometimes and sound like a jet other times.  temp gauge steady at 210.  Knowing the fans are indirectly controlled by the sensor, I ohm it out and found it was 200 ohms off of spec.  I know this wouldn't be a deal breaker, but I figured I'd replace it anyway. This did drop my temps by only a few degrees in the scan tool and was a little closer match to the IR temp gun.  With all of this, I was still noticing the fans on at random times.  I thought maybe it wasn't circulating as it should so I tossed a water pump on it.   Still no change.  I'm still leaning toward the thermostat being the issue as I do notice temps in the scan tool that corresponds with the range the fans should run in the service manual.


Keep in mind the fan does not stay on after the truck is off, and the temp gauge is showing 210 as it should.  The cab temp is working as it should.  Everything in the cooling system triangle is new with OEM except the thermostat.


The service manual also states the fans will run if the AC pressures are too high, which I know its winter for me but with automatic temp control I know the AC will run year-round.  Just strange that would randomly increase.


so I went to the local dealer and was told it would arrive in July.  I scour the internet for an OEM unit and nothing.  It's like they had a flash sale on them and POOF...gone.


I guess after I have written this short story if anyone else has seen this happen and/or if I'm right to think the aftermarket world is not able to make the thermostat as GM requires?

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