My issue started when one day from work my temp gauge dropped to the cold mark and the AC stopped blowing hot air also check engine light came on. Replaced thermostat and ECT sensor this had gauge working for a day but now it's back to the same problem as above.
My car has 145000 miles.
My car has an automatic transmission.
This is a common issue on this generation of the Chevy Malibu. This could be any one of a few problems. This could be a result of a bad BCM (Body Control Module). This is a module in your car that receives signals from other devices and turns them on or off depending on the inputs it receives. You may also have a faulty refrigerant switch or potentially a faulty A/C clutch.
I have also seen this happen even when the battery terminals are very dirty. If this is the case, you may also want to have the battery tested to see if it is capable of holding a charge. If you would like this done, a local expert from YourMechanic can come to your home or office to diagnose the Check Engine Light as well as repair your temperature gauge issue.