Thermostat or ECT Sensor?

C283

MEMBER
2008 CHEVROLET MALIBU
2.4L
4 CYL
2WD
AUTOMATIC
190,000 MILES

A couple weeks ago my car's temperature got really low then check engine light came on. I took it to AutoZone. Used a code reader it said thermostat, but after a day the temperature went back to normal and engine light disappeared. For a week it was normal. Then today the temperature went back down cold again, you can hear the fan motor going but for some reason it shut off the air compressor, so A/C was not blowing out cold air. No engine light, Then the temperature went back to normal, and the air compressor was working again. I didn't understand if it might be the thermostat why would it shut off the air compressor? That's why I was wondering if it might be something electrical going? Appreciate any help.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

When the engine gets too hot the A/C is turned off, so the engine does not overheat. It sounds like the thermostat is sticking to me, but you are right it could be the engine coolant sensor as well. Let's try the thermostat first. Here is a generic guide to help you see what you are getting yourself into when doing the job with instructions in the diagrams below. Also, it shows the engine coolant sensor which is in the thermostat housing.

https://www.2carpros.com/articles/replace-thermostat

Check out the diagrams (below). Please let us know what happens.

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Thursday, August 11th, 2022 AT 5:57 PM

C283

MEMBER
7 POSTS

Is there any way to figure out what is really wrong with the thermostat or the sensor? I just want to make sure I don't want to spend money for the part and replacing it and the problem is not fixed. I checked the wires to the sensor, and they looked alright. Can a bad thermostat do like I said where it would be stuck open then go back to normal for then be stuck open again then go back to normal. If there is some way I could figure out which it is? Thank you for any help.

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Thursday, August 11th, 2022 AT 6:33 PM

KEN L