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Running Hot

1474 Views 13 Replies 8 Participants Last post by  egtdude
It´s been quite a wet month thus far for April. In the past 6 weeks, we´ve gotten over 10 TEN inches of rain. It´s wet, cold, and windy.

Here´s the problem: when the car is running and the A/C is OFF, the car runs hot because the cooling fan does not engage. When the car is running and the A/C is ON, the car does NOT run hot because the cooling fan DOES run. So anytime I´m idling, say in a drive-through, I have to watch the temp needle and hit the A/C for especially long waits. Nothing I can´t manage, but annoying when I forget. Has anyone experienced this - if so what was the culprit and what was the solution?

I will be replacing a stuck (open) thermostat this weekend, been driving all week in this condition so it´s been a chilly ride to work. Dunno if replacing the thermostat will fix the cooling problem, I´d think not since problem appears electrical in nature.

Anyone know?

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There should be a thermostat switch in the radiator.. this is what triggers the fan when the A/C isn´t on. It shouldn´t click on until the temp gets up to nearly 3/4 of the temp gauge... which is just barely under the overheating mark. You can probably get a lower temperature switch than stock if you´d like it to engage earlier.
If your a lx, under your coil pack there are two sensors on the heater hose, one is for the temp gauge and the other is for the fan. I dont have my book in front of men but if you need more help just let me know.
You can always test the thermostat by removing it and boiling it and see if it opens. If it works fine then replace and look elsewhere.

Having said all of this I´d look for an electrical problem first. Sounds like a bad relay or temperature sender. On my 1995 LX there were only 2 temperature senders on the car, one for the gauge and one for the computer. The one that goes to the computer also sends the signal to the fan relay. I older versions have a separate temperature sender for the cooling fan. At least that´s what I learned from the junkyard, they have 3 sending units where as mine has 2.
Thanks Jeff.. sorry about that.. :-[ I´ve only ever seen them in the radiator before. :-|
Thanks all. I hadn´t thought about boiling the thermostat - neat trick. Probably going to change it regardless as its about time for a coolant change, looking old in there! So the consensus is that my temp sending units might be bad eh? I´ll check those during the thermostat replacement. IF it would ever stop raining. I swear, we haven´t seen the sun here in like 5 days. Of course, this means nothing to those Canadians above the arctic circle....
well if its just the fan if you look at the thermostat housing, there´s a wire that goes into it...its the temp sensor that kicks the fan on...it could have gone bad. Brian (ScortGT) simply wired it to a switch that grounds the circuit and can kick the fan on whenever he wants.

caution, that circuit pulls like 30+amps

10-04-2003 at 16:49, TheBlade wrote:
Brian (ScortGT) simply wired it to a switch that grounds the circuit and can kick the fan on whenever he wants.


I have seen this may times and I just shake my head :-?
I have this pet peave about fixing things right, If I ever wire my fan to a manual switch I will kick my own ass. That just taking too much of a chance, some hot day you´ll be sitting in traffic having the radio cranked and forget about the over heating motor. My opinion is find out what when´t bad and replace it with the correct part so it works just like ford intentid.
Sure you could wire it so the fan is on when the car is on, thats not quite as bad, but still not 100% correct in my book :p
10 inches of rain in 6 week? damn in south florida 10 inches is like 6 days. lol.
It´s funny - last year we were in a drought condition, this year we have flash flood warnings. There´s never any moderation in this area.

I´m saving up for new springs/struts so I will likely just change the thermostat this weekend and probably just wire the fan to be on all the time. Not 100% correct for sure, but it´s a quick fix for the time being. Since the birth of my son last year, free time for car stuff has been luxury.

10-04-2003 at 21:10, Kenny wrote:
10 inches of rain in 6 week? damn in south florida 10 inches is like 6 days. lol.


we got you topped - last week we got 10 inches of SNOW in 2 DAYS! :-?
at least it´s all melted now...crazy weather...
Mine is a 1995 LX model and it does not have a separate temperature switch for the fan. It uses the one for the computer. I suspect that the 1995 GT uses the separate sensor for the fan, which I think it the one closest to the firewall. In either case, you could simply have dirty contacts on the sensor. Mine did and it was causing an intermittent high idle when warm problem. Had to remove it to cleam it properly though (and it was a real pain to find a 25MM deep well socket to remove it with also). When I was at the junkyard I saw several other temperature sensors with dirty connectors. Worth looking into.

[ This message was edited by: zzyzzx on 18-04-2003 13:04 ]
there is a sensor for when the AC is on and one for normal use. I had this problem when I first got my scort. By the time I got it home it was boiling... and thats about three blocks. turns out the guy drove it with the AC on when we were meeting at the bank so he didn´t know about the problem. I got him to pay half the cost of replacing the other one though,.
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