I've got a 2002 Ford Focus ZTS (w/ the 2.0L DOHC Zetec engine) that I generally take good care of, but lately I've had an issue with the engine overheating. Idling more than 15-20 minutes will have the engine temp creeping up, and for some reason the fan never cuts on.

I was thinking the thermostat was/is dead, but fan timing operates normally when the A/C is on so I wasn't sure if that was it.

Any agreement that the thermostat is the issue? Or do you think it's something else?

8/4/2005 1:16:11 PM

is that idling with the ac on?
does it still do it with it switched off?

8/4/2005 1:35:43 PM

^
it overheats when it's idling with the A/C off.

when the A/C is on, everything is in normal operating temps.

8/4/2005 1:45:28 PM

Check you fan switches; one of them is probably bad.

8/4/2005 2:14:48 PM

if turning on your AC gets your system ok, then it means your fans not operating is whats causing the overheating

i hope its true of your car that just idling w/o rad. fan usage is enough to overheat it, or else your diagnosis is off.


diagnose thermostat by holding the upper radiator hose comming off the engine block.

its starts cold...then should warm up. compare that hose to the feel of the rest of the hoses, once the car reaches norm operating conditions, it should be just as hot.



i thought i had your problem -- i know it sounds weird but just trust me and BLEED THE AIR OUT OF YOUR SYSTEM

my temp switch for the fan wouldnt cut on becuase it couldnt sense the coolant temp becuase their was air in their.




[Edited on August 4, 2005 at 2:41 PM. Reason : -]

8/4/2005 2:36:29 PM

with the ac on, the fan runs all the time, when it is off, it only runs when the temp swith cuts it on. there should be a temp sensor with two wires on it somewhere on the top of the engine in the head that tells the ecm what temp the engine is and when to cut the fan on. that is where your problem lies, find it, replace it, no more overheating.

8/4/2005 2:36:47 PM

turn it on, let it idle.

open hood. is the fan on?
turn ac on. did the fan come on then?

it may just be a fan switch like someone else mentioned. i would check that first. i had the same problem with my rabbit, and the switch had just come unplugged.

[Edited on August 4, 2005 at 2:47 PM. Reason : on the rabbit, the switch/sensor was on the side of the radiatior]

8/4/2005 2:47:26 PM

^ fords are usually in the intake or head near the thermostat, they use a computer controlled fan relay, its not a full current switch, it only had a 5 volt reference signal on it

8/4/2005 3:11:09 PM

VTAK! i mean ZTAK!

8/4/2005 3:21:08 PM

FORD

8/4/2005 10:47:33 PM

Worked on it some more this morning (with my grandfather coming down from VA and insisting he watch over my shoulder to make sure I didn't fuck anything up ).

I can now rule out air in the line as a problem, and all of the switches were properly connected so far as we can tell. My grandfather thinks one of the relays is blown somewhere.

Providing a little more clarity on the A/C diagnosis: when the A/C switch is on, the fan operates normally but it doesn't run all the time.

When the car has been sitting idle after 5-10 minutes and you switch on the A/C, the fan will cut on after about 30 seconds, run for about 30 seconds, then cut off. It will cut on after that periodically when needed.

When the A/C is not on, that cycle never occurs. The fan will never cut on at all.

[Edited on August 6, 2005 at 12:02 PM. Reason : ---]

8/6/2005 12:02:23 PM

then obviously whatever temp system that triggers the fan to come on normally is fucked up somehow...could be a relay, could be the sensor..but thats what it is. the fans operating like that with the AC on is normal.

[Edited on August 6, 2005 at 3:42 PM. Reason : a]

8/6/2005 3:42:42 PM

somerthing electrical around those switches...

[Edited on August 6, 2005 at 4:13 PM. Reason : -]

8/6/2005 3:55:13 PM

my diagnosis is either the relay or the coolant temp sensor, both easy fixes

8/9/2005 10:43:18 AM