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Discussion Starter #1
Hi everyone,

My recently purchased 2002 ZX3 started overheating yesterday only at idle/low speeds. When I checked the coolant level was just below min. so I filled it. This morning drove car around some and it started to overheat again and actually stalled. Was able to make it home, checked coolant and it was nearly empty.

Researching the forum, symptoms match those of faulty cooling fan resistor & its pigtail wiring harness. So I went under the hood to check their condition and found there is nothing plugged into the resistor at all!

Looked everywhere for the missing plug but its nowhere to be found. The loom that its supposed to come out of is there and plugged into both fans. And I noticed someone spliced two green wires that come out of that loom together. Is it possible this was done to somehow bypass the resistor?

Would the car run at all without the resistor connected to anything? I thought for sure this was the cause of my overheating problem but if its never been there then I guess its not likely and I should look elsewhere.

I should also mention in case its relevant the only tampering done to the car recently was a refrigerant charge about 3 days earlier (which didn't work, a/c still blowing hot air). I read on here that with a faulty resistor you can just turn on the a/c to force fans to come on until you get it fixed but since my a/c doesn't work I guess that's not an option for me.


So I guess my two questions are:

1) would the car run with nothing plugged into the cooling fan resistor?
2) would the overheating be causing the coolant loss or vice-versa? or is it possibly unrelated?


Thanks for your help!
 

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It will run without the resistor. Fans don't run all the time unless the A/C is on. Cooling loss could be the infamous thermostat housing. Every Zetec goes through many in their lifetime. Look over the transmision for evidence of a leak. It doesn't always reach the ground.
 

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Discussion Starter #3
Thanks! The plug that is missing is the one labeled "C1027" in the pic you posted.

I will check the thermostat housing as soon as I get home. Not sure what I'm looking for but I'll check if there are any threads about it. Was also reading here it might be hairline cracks on the coolant reservoir-apparently another common issue.
 

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Yeah, I've done the reservoir also. That's about $40.00 fix. take the 10mm bolt out of the fender and work the little catch out with a flathead. Then you can flip it over and check. With the t-stat housing, the valve cover leaks onto the housing and the oil will cause damage. The O-ring gaskets also fail. Look for an oil leak above the housing. It doesn't take much. There are plenty of threads on the t-stat problem.
 

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The resistor is for "low" speed fans. Low speed fans kick on to maintain operating temperate at the high end. Without the resistor (just a dropping resistor) the low speed circuit is open and not working as you have found out.

The high speed fans kick on as your last defense against overheating and engine damage (as stated above - high speed always on when A/C is on). But you do have the 'limp mode' for emergency cooling.

So I'd think that only having your high speed fans kick on is probably letting your engine get too hot too often and maybe a reason for coolant loss also. You may want to get the low speed problems corrected.
 

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Discussion Starter #6
Thanks everybody. Turns out my overheating issue was caused by a bad radiator. Got it replaced and car is running fine again. Still going to order the resistor & pigtail to connect everything as it should be though.
 

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actually ive got a question while theres a thread for it going....my cooling fan runs non stop...once warmed up...it kicks on for bout a min then shuts down after a lil more running it, itll kick back on and stay on...any idea why i would do this i have looked into anything under the hood im just going off of what it does and ive been running it like that for about year and half
 
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