Cooling fan not working?

I notice that sometimes the temp. gauge goes near red and the engine runs hot for awhile, then the passenger side 4 fin fan runs, but the driver side 7 fin fan does not run. I tried messing around with the A/C controls trying to see if it ever will go on, it won't. I tested the fan motor, it runs fine. I think maybe a relay sensor or fuse or something may have gone bad, has anyone had this problem?

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|| dm22 ||| AOL - dm22dm22 ||

1988 TurboCoupe (I call him whitey)
-- 5-Speed
-- STOCK

As a quick check of the fan / relay system, pull the connector off the ECT sensor (sticking up between injectors 2 and 3), and jumper the pins in the connector. This will tell the EEC that the coolant is VERY hot. Turn on the key, and both fans should run. If they both dont run, you have a fan, wiring or relay problem. Normally, if the temp gauge is anywhere near calibrated properly, the pass side fan comes on when the temp gauge gets about 1/2 way up, and the drivers side fan will come on if the gauge continues to climb to 3/4 of the way up or so. If both fans come on with the ECT connector jumpered, I would suspect either a inaccurate temp gauge / bad sender, or the ECT is going bad. Another slight possibility... if that small coolant hose that goes into the pass side of the lower intake manifold is plugged up with crap, or the fitting on the lower is plugged, severely limiting coolant flow to the ECT, it will report a lower than actual temp to the EEC, and the EEC will turn on the fans late.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)

Also, there's a fan temp switch underneath the lower intake in the center(single wire).

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Dave
'83TC
'85TC
'87TC
'90SC

Gee seems everytime I THINK I remember who the fans work someone explains them differently.

When the car is first started, the big to fan, passenger side comes on and cycles.
That fan is also the fan that comes if the A/C is running. I thought that is ALSO the first fan to come on when the engine temp hits a certain position. The lower driver's side (smaller fan) only comes on when the temp has gotten to a higher level. At which point the big fan should already be running, A/C on or off doesn't matter.

Am I wrong?



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Kevin
TCx2
88 White TC, 5spd, Loaded
88 Black TC, 5spd, Base
87 LtBlue TC, 5spd,Loaded

I read in the Thunderbird/Cougar official manuals that the passenger side 4 blade fan comes on when the engine temp reaches a certain level, I think it's about when the temp guage gets to about halfway up. The 4 blade fan also comes on when the A/C is on. The driver side 7 blade fan comes on when the engine temp is even higher, like about 3/4 the way up. Also the 7 blade fan comes on when the A/C pressure gets to a certain level.

I did some messing around with different things under the hood and found that the A/C fan pressure switch is bad. It's not telling the 7 blade fan to go at the right time. I bought the part at a local store for $20 but I haven't installed it yet, I'll do that tomorrow. I'll post results of my installation for anyone who may have had a similar problem.

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|| dm22 ||| AOL - dm22dm22 ||

1988 TurboCoupe
-- 5-Speed
-- STOCK

dm22 is correct on the fans, You should also check and see if any of the other gauges seem to move when the temp gauge goes up. This is the problem that I was having with my 88 TC. All the fans work but the gauge shows that it is running hot. I replaced the cluster volt reg but I still get odd readings out of my gauges. I raise the hood at least four times aday just to make sure it is not running hot.
just my 3 cents worth.