2004 Kia Optima Overheating and heater stopped work

The heater acts as an additional mini radiator to cool down the coolant. Sounds like you may need a new radiator.

There is no adjustment on the cooling fan. If the car overheats, there are only a few things it could be. First, with the engine off and cool, check if the radiator is full of coolant and it looks clean.

The most likely cause of overheating is a stuck thermostat. You will need to drain the coolant and replace the thermostat. You can locate it easily by following the top radiator hose to the housing on the engine. The thermostat is under this housing.

You could also have some kind of blockage on your radiator. If there is a lot of dirt in the fins, air cannot circulate and remove the heat. Use some compressed air to blow the fins clean.

thermostat needs to be changed

Classic signs of a bad water pump. When on the freeway, the circulation of coolant through the system is increased due to the speed but once you slow down, it will tend to overheat. Please post back with any other questions or just to rate the solution. Thanks very much!
Greg

If it's cooling properly while in motion, then it's most likely the fans aren't kicking in. Check fuses for the fans and also the temp switch that controls the fans.
Also, in a pinch situation, if out on the road and it starts overheating, roll down the windows, and turn the heater on full blast with the fan blowing...it''ll be uncomfortable, but your heater core can act as an emergency radiator...
K

Sounds like your cooling fans on the radiator are not working.

this would be your cooling fan module located by your air filter mounted on the core support.

The window washer doesn't work in our 2008 Kia spectra, and we have plenty of fluid in the resourve

To check if it is the thermostat run the car and when the temp starts going up turn the heat on full blast in the car. If the temp goes down after you turn the heat on than it is your thermostat.

I figured this out and fixed it on my 2001 Optima. Mine was an electrical problem, not an overheating problem. The problem shows up when there is a heavier than normal load on the electrical system. For most of us, this is when the air conditioner is running full-blast on a hot summer day. However, it was also occuring when I ran the heater full blast. The heater running full-blast should have lowered the temperature, not raise it. So I tested the coolant temp while the gauge was showing it overheating. The coolant temp was not increasing, but the gauge showed that it was. It is caused by a bad ground connection. Another test you can do to see if your problem is the same as mine is this. As soon as the engine is showing overheating, pull over, park the car and turn off the engine. Immediately start the engine again and see what the temp gauge shows. If it still shows hot, you'll know you've really got overheating coolant. If it goes back to normal range, you'll know it's just a bad ground connection. Turning off the engine eliminates the resistance in the electrical system that has beeen building up and causing an erroneous high temp reading.

To fix: Either find and clean ground connections throughout the vehicle until it fixes it, or do what I did. A mechanic at the Kia dealer showed me this. I ran a new wire from an empty bolt-hole on the top of the engine to a bolt into the frame behind the engine. I only added a 6 inch wire and a new bolt into the top of the engine. The bolt into the frame was already there, so I just removed it, put the wire under it, and replaced the bolt. It created a redundant ground that prevented the build-up of resistance that caused the erroneous temp reading. It was a 5 minute fix and it has never done it again. Kia knows about this problem and they put out a post to their shops on how to fix it.