I have a 2002 Focus. It overheats when I am sitting still. I changed the engine cooling fan relay and it still overheats. I can hear a fan come on when I turn on the A/C, so I know a fan in there is working. I really don't know too much about cars. Help please! Any ideas?

Is the coolant level OK? how do you know its overheating? does it smoke? loose power? what colour is your coolant?

If you leave it idling the fan should come on after a while without the AC on. As you've proved the fan is working by turning the AC on it suggests maybe a faulty temperature sensor.

When it overheats the guage goes up to red, it stinks and sometimes smokes, obviously overheating. I turn the heat on all the way up to try to pull heat off the engine and pull over to let it cool off. It only overheats when I am sitting still after driving it for a while, like a red light or drive through. The coolant looks normal and is resevoir is full. I just had oil changed and all fluids topped off a couple months ago. I have noticed while I am driving that it seems kind of weak, acting sluggish. I am wanting to try to fix this without taking it to a mechanic. Where will I find the temperature sensor? I changed the one marked engine cooling fan relay.

I'm having to rely on the information in the Haynes manual so I can't be 100% sure of my facts but according to the manual both the temperature gauge and fans are controlled by the ECU from a signal from the engine temperature sensor. Some makes of car have another sensor fitted in the radiator to control the fan directly but this doesn't seem to be the case for the Focus.

Since your gauge is working the sensor would also seem to be working and since your fan comes on with the AC that also seems to be working so it seems a bit odd that it doesn't come on when the engine temperature rises.

Does your temperature stay normal as long as the car is moving at a reasonable speed and is the performance ok then? The ECU will cut out some cylinders to protect the engine if it detects overheating which may explain it's weakness and sluggishness.

Do you know if your car has two fans (does it have the High speed fan relay C106)?

It does have a C106 relay! So I should try replacing that one too? I got it out and looked at it and it doesn't look burnt out or anything, but neither did the other one I replaced. I sure do wish I would've paid more attention when my dad was trying to teach me about cars lol! Thanks everyone for being so helpful!

Oh and yes, the temp stays normal as long as I stay moving pretty good. If it's stop and go or idling is when it overheats. It sure seems to be just slightly sluggish though after driving it for awhile.

ECU = Electronic Control Unit (may also be referred to as PCM = Powertrain Control Module).

If the C106 relay is the same as the C1015 that you changed earlier, which it appears to be in the circuit diagram, then you could try the one you swapped out. As the replacement didn't make a difference it's probably ok.

if you undo your coolant cap, is it pressurised?

2002 Focus with A/C is shown as having 2 fans.

Normal engine cooling turns fan 1 on + fan 2 at low speed.

With A/C on fan 2 runs at full speed.

Check to see if you have 2 fans on the radiator.

Hi Angie, just as an after thought, because no one else has mentioned it yet, but is your radiator getting hot all over or staying cold?? Was thinking maybe the thermostat is not working properly?? Might be worth a look!!

Hope it helps...

Chris

if its cooling down when you put the blowers on to hot it could be a blockrd radiator . do you use tap water or de ionised water if you need to top up ?

youd want to check the cap on the expansion tank first if it holds pressure and then look at the thermostat to see if it is opening correctly, like said above

Common faults on this car are the pressure cap being faulty the system is pressurized so if theres not a tiny hiss it could be faulty cheap thing to replace anyway after that thermostat let it idle and see if the top n bottom hose and rad get hot then the water pump

All good advice but the original post said that the car overheated when standing or in stop/go traffic and the fan didn't come on. I've already asked if it stays at normal temperature when running at speed and she says it does so I would have thought that would eliminate these other possibilities and point to a fan problem.

Its a two speed fan so no way of telling till you let it idle and watch it also shouldn't overheat that quickly either even in hot weather so the fans not the issue the issue is why is the car overheating so quickly

The fan is a two stage fan it will come on with aircon so you need to let it idle and watch the fan if the gauge hits red and the fan doesn't come the car shouldn't overheat at a drive through or red light so it sounds like the water pumps the issue not a fan