[Calvear0]

Originally Posted by ctrlz

I take it that is a thermostat on the fan unit. Nice to know it is a separately serviceable piece.

No, I don’t think it was on the fan. They said the thermostat was stuck open

[Randall08]

Mine also stays on every once in a while and I also just disconnect the battery terminal. But I wish I knew what what was causing the issue

[ctrlz]

Originally Posted by Calvear0

No, I don’t think it was on the fan. They said the thermostat was stuck open

That should have been pretty easy to pick up on the temperature gauge. You also tend to notice the lack of heat in winter! (edit: I see you are in CA, maybe not as noticeable there!)
And this got bumped up to a case with GM?
And why, if the coolant thermostat is stuck open (and the coolant therefore always cold), would the cooling fans stay on???
Most fan modules now sense the radiator temperature and adjust the cooling fan(s) speed(s) accordingly. In cold weather, the fans might not even come on for a while. The exception is typically for A/C, where the fans automatically go to high speed when the A/C is active.
Just hope it all works for you now.

[Calvear0]

Originally Posted by ctrlz

That should have been pretty easy to pick up on the temperature gauge. You also tend to notice the lack of heat in winter! (edit: I see you are in CA, maybe not as noticeable there!)
And this got bumped up to a case with GM?
And why, if the coolant thermostat is stuck open (and the coolant therefore always cold), would the cooling fans stay on???
Most fan modules now sense the radiator temperature and adjust the cooling fan(s) speed(s) accordingly. In cold weather, the fans might not even come on for a while. The exception is typically for A/C, where the fans automatically go to high speed when the A/C is active.
Just hope it all works for you now.

That's what I said! I work with techs and they all told me the thermostat would be stuck open and sure enough.
figured I'm still under warranty, easy fix and I'm covered but took them a week.
I just hope this was the issue and it doesn't come back

[Kennedy_space]

Hey, I'm having the same issue with my 16' LT. The dealership ended up replacing my thermostat housing unit and was working fine for about a month and now its back to being stuck open (even with the new thermostat). How has your car been running since they fixed it?

[Randall08]

Mine did all those things to and I ended up replacing the coolant temperature sensor last week. Hasn’t happened since. Fingers crossed though!!!!

[KelvinnDC]

Update on this? My car has been doing the same thing

[Mountain]

If the ECM sees an issue with knowing the engine coolant temp, it will command the cooling fan on all times as soon as the car is started. Circuit concerns, inoperable parts, extensive leak - whatever. Just an FYI.

[Ajrothm]

Just an FYI for future searchers...

I also had the “fan stays on high and temp gauge on 0”... No check engine light on. Fan would run full speed for 10-15 mins after the engine was shut off.

After driving the car for an hour, I noticed there was no pressure on the upper radiator hose, this led me to believe the engine really was running cool.

I pulled out the thermostat, it appeared to be stuck open slightly. So I got a new stat, compared/measured them and the original stat was open about .060” or so. Not much, but it was enough.

Changed the stat, cleared the two codes it had stored (p480/p691). Started it up and within 5 mins was showing some temp on the temp gauge and the fan was not running.

So in my case, it was NOT the coolant temp switch. The car is bone stock and has 51k miles.


Afterwards, I boiled the old thermostat, it opened WAY up and stuck there. Even freezing it, it would not return to close or even move at all...

Thermostat was $120 at the dealer and it was in stock.

[JCunningham]

whats the part number on the stat

[gtfoxy]

Originally Posted by Ajrothm

Just an FYI for future searchers...

I also had the “fan stays on high and temp gauge on 0”... No check engine light on. Fan would run full speed for 10-15 mins after the engine was shut off.

After driving the car for an hour, I noticed there was no pressure on the upper radiator hose, this led me to believe the engine really was running cool.

I pulled out the thermostat, it appeared to be stuck open slightly. So I got a new stat, compared/measured them and the original stat was open about .060” or so. Not much, but it was enough.

Changed the stat, cleared the two codes it had stored (p480/p691). Started it up and within 5 mins was showing some temp on the temp gauge and the fan was not running.

So in my case, it was NOT the coolant temp switch. The car is bone stock and has 51k miles.


Afterwards, I boiled the old thermostat, it opened WAY up and stuck there. Even freezing it, it would not return to close or even move at all...

Thermostat was $120 at the dealer and it was in stock.

Good catch & test.

Long ago I got in the habit of testing new T-Stats out of the box & test once a year.

People would be amazed at the actual failure rate.

Most times it was a binding in the shaft or a spring rebound/ tension issue.

I’ve noticed from time to time my car having the fans stay on after shutting it off.

My plan is to start some diagnostics this spring when & if it reoccurs.

[ctrlz]

Originally Posted by gtfoxy

Good catch & test.

Agree! Two thumbs up for doing the failure analysis!!!

[Ajrothm]

Originally Posted by JCunningham

whats the part number on the stat

GM# 12674634

[classicrockr]

Mine just did this. Fan stays on, check engine light on and temp gauge not moving from 0.

This extended warranty from ally better cover it.