[STLmalibufan]

I have a 2012 Malibu LTZ v6. My car temp gauge is fluctuating. It will be under the half way mark then go up to the half way mark the drop under it. I was doing some troubleshooting its leaking. I just had thermostat change. What i do seem to notice that my fan will come on when it gets to that half way mark and then the temp drops down. When my a/c is on the fan blows high and when i turn off the a/c the fans turn off and then it start fluctuating And when i turn off the car or have it on the on position but the car is not on the fans doesn’t turn on. So I’m wondering is there something up my coolant temprature sensors of do i have a bad fuse. I’m at a losss. The car is not overheating it just bugging that it not holding stead.

 

[STLmalibufan]

Update
I used a infrared thermometer when it was above and it showed about 200 F and i also have a scan tool and when the car was on the on position read around 230F. I took it to a mechanic and the did a pressure test on it and they said the pressure was good and i have no leaks as well. I had the thermostat changed but it was still doing the same thing but one mechanic said it was fine. I took it to another mechanic and showed him as well. I had some other work done to my car and whoever worked on my car last switched my coolant to green coolant instead of having it orange.they said i will need to get a flush and also a new thermostat. Anybody think that could be the case?

 

[DrivenDaily]

You won't need a new t-stat if it was already replaced, but you'll need to completely flush the cooling system and rinse it well so that there are not 2 different types of coolant. When they mix, the mixture turns into gel.

Whoever added that green stuff to your pink/orange stuff needs to pay to have it done, not you, unless there's no way to prove that they did it.

 

[STLmalibufan]

You won't need a new t-stat if it was already replaced, but you'll need to completely flush the cooling system and rinse it well so that there are not 2 different types of coolant. When they mix, the mixture turns into gel.

Whoever added that green stuff to your pink/orange stuff needs to pay to have it done, not you, unless there's no way to prove that they did it.

Thanks, DrivenDaily I'm going to try to see if i can pull up some type of proof that the other shop changed and ill see about having them paying for but definitely will get that flush when i get a chance!

 

[DrivenDaily]

So long as you're not driving it, take as long as you feel.

But if you intend to drive it, even if all you do is drain as much as possible and then fill it with water, it'll be better than having that bad mixture.

Back in April 2019 I had to replace my t-stat that failed in a closed position, overheating my 3.6L V6 engine. I decided to replace as many hoses as I could get (all but the 2 heater hoses), the water pump, t-stat, and serp belt. To be sure that any issues wouldn't make me replace new coolant, I drove on water for about a month. The very next week after doing all this saw me make a round trip of 1500 miles, all with no issues!

If the coolant has NOT been mixed but instead was completely replaced, then draining it isn't such a hot-button issue. But you'll want to do so regardless, since the orange stuff protects the aluminum engine parts better than the green stuff.