2005 kia radiator fan wont come on

SOURCE: 2001 Kia Optima over heating

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.

SOURCE: 2005 kia sedona. a/c fan

There is a Technical Service Bulletin on your particular issue, but keep in mind that this is not a recall---this is a dealer advisory:
On some Sedona (GQ) vehicles built from May 1, 2001 to August 30, 2005, the heater coolant pipes may corrode and leak without warning. During scheduled maintenance, oil changes and/or other vehicle service, inspect the heater coolant pipes for severe corrosion. I know kia sedonas are prone to headgasket blowouts. check and be sure that coolant in radiator is up to par. above may or may not apply to you ! just letting you know about problems with sedonas. Find the temperature sensor (repair manual is helpful) and touch wires that go to sensor together, watch your fingers in the fan. You may need power on. If fan does not run still. check relay and fuses in fusebox, if it still wont run. run a wire from positive on battery to positive wire at fan connector, you may need to ground the other wire. turn car to on to test it do not start it. if fan runs its most likely the fan relay or coolant tempurature sensor. a/c does have a relay in fuse box!! good-day ! hope above will help you !

SOURCE: I have a2002 Kia Optima, the drivers side Radiator

You vehicle should have an AC relay to control the fan when the AC is on. It is located under the hood in a power distribution box with a removeable lid. The lid should have a list of the area where the relay connects to the connection port. The relay is most likely the issue and is very common to fail.