Engine overheats sometimes while driving or sitting still.ac works and so does condenser fan. Radiator fan does not work. 1st thing i tried was replacing radiator relay switch under hood next to battery. Right when i plugged the new one in the fan started working but it seemed like it wasnt going to fast.got back on the road and engine started overheating again.got home unplugged and plugged new switch several times and fan does nothing???????

the ac fan starts as soon as the ac is switched on
the fan is provide cooling of the condenser before the radiator to prevent high head pressures in the ac compressor
it is the fan at the front of the car mand does not affect engine temp
there is a radiator fan between the engine and the radiator that will not start until the coolant temperature reaches a set temp at which point the ECM switches that fan on
if that fan is not working when the engine is hot , check for fan, coolant temperature sensor switch , fan relay, fuses or problem ECM

The radiator fan should come on when the ac is running, and when the coolant reaches 230 degrees. Can you jumper the fan relay to make it run ?

Most cars have an 2 electric fans on the radiator. One will run when the coolant gets hot and the other will run when there is more cooling demand OR it will run when the AC is turned on. My guess is, the second fan is not running when your AC is. Your AC system creates heat of its own. The heat is removed through the condenser (radiator-like coil) which is usually located in front of your engine radiator. Without a fan the heat is transferred into your engine radiator causing it to over heat. This would explain why it overheats while idlling and not while driving. While driving, air is flowing through the radiator and condenser. to provide the necessary cooling. In short, check to see if both fans are running when the engine is hot and the AC is turned on.

This indicates that the booster fan for AC has failed. If you look in back of the radiator, you will see 2 electric fans. One is for the engine cooling, and the other is a booster for when the AC is running to provide for extra air flow through radiator and AC condenser. (May also apply when engine overheats, but not sure of that) As car is moving along, then air is pushed through allowing AC to work. When standing still, and fan failed, then no air (or less air) passing over condenser grill. (Condenser is the one in front of the radiator) No cool.
While standing still with engine running, open the hood and look at fans. Watch your fingers. Fans can start at any time. One may be running or not. Now turn on AC and look at fans. Both should come on together. If not, then it may be either the fan, or the fan relay or fuse. Or even the wire.
Does the engine get extra hot while standing still running? Let it sit there for ten mins or so and see if main fan kicks on. Watch your temp gauge, you dont want it to boil over. When the temp reaches the level it is at normally, one fan should kick on. If temp keeps climbing and no fan, then that may be the same issue, likely the main relay.

hi
1st u have to replace condenser fan and radiator assy , it will solve your problem , cause due to no coolant radiator fan is not working and cause of engine overheating a/c system got trip . replace both condenser fan and radiator and put new coolant. thanks.

If it is a regular fan, check the fan clutch. If it is an electric fan, make sure it is coming on. Other than that you might be sure the AC condenser that sits in front of the radiator is not plugged up with grass, bugs, etc...

It is not the thermostat since it only overheat on stop n go situation. Most likely cause is a bad radiator fan. Turn on the AC and see if both the radiator, and the condenser fan works. They should both be working when the AC is turned on. Lets stick to this for now. Let me know what happened. I don't want to confuse you with too many possiblity.

check the fan if no air air though the radiator and condenser the heat will cause the presure swith on the ac to turn it off and on sitting still

your AC cooling fan is not working properly, most vehicle has two fans, one for the radiator and another for AC, both work in sync with one another; if one cooling fan only working it does not produce enough cooling for both radiator and condenser at the same time; by running ac you producing more heat and its cant cool the engine fast enough with one fan so your engine is overheating when running AC. The temperature sensor could be faulty and need to be replace or your fan motor can also be faulty. Check the fuse first and the relay make sure they are not burn out. sensor cost about 30 bucks get it new, relay 35-40 new used 5 bucks at junk yard, fan get it from a junk yard for 25-30 bucks, new will run over 100 bucks. don't run the air and overheat your motor, it can damage your engine or may blow your radiator. if you do run ac watch the temp very closely, don't let temperature get into the red.

we have a 2003 and it did the very same thing . Its called cooling fan relay it costs about 60.00 and is located behind the headlight assembly . not very hard to fix if you know anything about cars .