2016 FIAT 500X Trekking Plus AWD; 2016 Kia Forte5 SX 1.6T A/T
You can test the thermostat the same way in hot water. They still work the same way.Yes it does that on highway with A/C on turning A/C brings it back to normal when the car was under warranty I had the same problem they replaced the thermostat like 3 years ago for a year it was fine but it came back so I wanted to see if the thermostat really works I filled up the spare tank with coolant and made the car overheat took the radiator cap off and the spare tank both but the water level was still the same even when I open the radiator cap and it spilled some out and I made the car overheat again I didnt notice coolant level dropped from spare tank so I am thinking its the thermostat when the A/c is off car is fine I shift gears on 5000 rpm never acts up but when I turn the A/C on then it suffers do you think my problem would be the thermostat or do you know if I can check that anyways? with old cars I use to take it off and put it in to the boiled water and see if it works but new cars arent like that I believe
While you were doing the experiment, when the coolant got hot on the radiator? I mean, at what point thermostat was opened? If A/C was off, would it overheat in this particular situation?