Engine Cooling problem
2004 Kia Optima 4 cyl Four Wheel Drive Automatic 96000 miles
My 2004 Kia Optima overheats only when I stop, meaning, that I could be driving with the A/C on and as soon as I stop at a red light, the car starts overheating. Then it goes back to normal once my car is in motion. However, I've found that if I not running the A/C and I stop at a red light that my car does NOT overheat. So, it appears that the issue only occurs when I use the A/C in my car. Do you know what could be causing this issue? I've already replace the coolant hoses and thermestat. I also checked all of the fuses next to the battery and inside the call. Help!
Sounds typical of the electric radiator fan not turning on. I'm not familiar with your car specifically, but when you're driving, there is air flow though the radiator. The fan is needed when the car is not moving.
Some cars have two fans, one for the radiator and one for the air conditioning compressor. On most cars, the AC condensor fan turns on either when the compressor cycles on for a few seconds, or it runs continuously when you're using the AC. If there is a single fan, it should do something similar plus it will turn on when the coolant temperature reaches around 210 degrees.
The first thing you can try if you never hear the radiator fan turn on is to look for the relay and switch it with a different identical one. A real fast way to test all the rest of the motor circuitry is to pop the cover off the relay, reinstall it, and squeeze the contact. The fan should turn on. If it doesn't, more testing is in order, but the motor would be the most likely suspect.