Heres the problem: my car will overheat (way past redline) in traffic or at idle unless I have the AC on. When I turn the AC on, the radiator fan turns on and cools the engine down quickly. Regular driving, there is enough air coming in from the air dam to cool the car down. I didnt want to rely on my AC to cool my car down, so I tried to fix it. I went under the car, and noticed that the connector connected to the fan switch was lose, I pulled it out, and noticed it was completely broken. I went ahead and made sure the wire itself worked, so I put the ignition on, grounded the wire, and the fan turned on.....that means the fan works and the wire leading to the switch works right? I went ahead and replaced the fan switch with a new stock one (wrapping it in teflon tape) and replaced the connector with a new connector from the dealership. Made sure again that my new connection was true by grounding the new wire and it worked....hooked it up to the new switch and locked it in place. Started the car up, let it reach all the way to redline again.......and still the fan didnt kick in......anyone have any ideas as to what else it could be? Thanks

------------------
http://users.ticnet.com/mult68
1992 Teal Camaro RS
T-Tops
305 TBI V8
Open air element
3" Flowmaster Exhaust System w/Quad Tips
Aiwa CD/Mp3 player
10 Disc CD Changer
Rockford Fosgate Speakers
SLP Headers Coming
Dynomax High Flow Cat Coming
More to come.

 

you check the thermostat? I just changed mine.. they're only a couple bucks.. don't forget to get a gasket too. the fan cools the radiator, and that coolant flows into the engine cooling it.. but if the thermostat's closed, it doesn't get in to cool.. (in case you didn't know, no offense if you did)

 

Well Ive had this problem since I got the car...and I went ahead and changed the thermostat then (about a year ago) And it still didnt fix it.....I am going to go ahead and change the thermostat this weekend.....but how would a bad thermostat cause the fan not to turn on?

------------------
http://users.ticnet.com/mult68
1992 Teal Camaro RS
T-Tops
305 TBI V8
Open air element
3" Flowmaster Exhaust System w/Quad Tips
Aiwa CD/Mp3 player
10 Disc CD Changer
Rockford Fosgate Speakers
SLP Headers Coming
Dynomax High Flow Cat Coming
More to come.

 

I've been thinking about this one for a while now.

Even if the thermostat was stuck, it should still turn the fan on, the ECM doesn't measure temperature at the radiator.

The fan control circuit is something like this.

Fan temp switch on passenger head tells the ECM when the coolant is too hot. The ECM grounds the fan relay and the fan kicks on.

The A/C also tells the ECM to turn to fan on, that's why when you turn the A/C on the fan comes on.

I can't find any diagrams right now, but maybe there are two turn on leads at the fan relay, both from the ECM, one for the temp switch, one for the A/C. I kinda doubt it, but it's possible.

The only thing I can think of is that the fan temp switch wire is broken somewhere.

Hope that helps..

 

If you can't figure it out, I'd just buy an aftermarket fan switch at Advance Auto Parts, they're like $18.

 

oh.. I thought you said the fan DID come on after you changed the switch.. I'm not sure about that then.. sorry.

 

I dont think the fan temperature switch wire is broken...when I have the key on and ground the wire, the fan turns on

------------------
http://users.ticnet.com/mult68
1992 Teal Camaro RS
T-Tops
305 TBI V8
Open air element
3" Flowmaster Exhaust System w/Quad Tips
Aiwa CD/Mp3 player
10 Disc CD Changer
Rockford Fosgate Speakers
SLP Headers Coming
Dynomax High Flow Cat Coming
More to come.

 

Samething happened to me last summer the problem ended up being a fuseible link for the fan. I replaced that and the problem was solved. Hope that helps you out.

------------------
David Higgins
1986 Black Iroc-Z
305 TPI
Edelbrock Cat-Back
K&N Air Filters

 

I can honestly say I've had experience with this system, and please don't waste any time or money looking at a thermostat. If the cooling fan isn't running at all, that's the actual problem. Since your car is TBI, and I have a Carb, I'm not sure whether you have a single or duel fan setup. I have a single fan system myself, so I'll stick with that system - - hopefully yours is simular. Try the following:

1. remove the wire off your old Temp sensor in the side of the block, and ground the wire. (You said you did this and the fan runs). - If the fan runs, you can rule out the fan motor or wiring going to the fan as the culprit.
2. You said you replaced your temp switch with a new one, and wrapped it in Teflon tape. I like Teflon tape also, BUT YOU NEED TO REMOVE THE TAPE! The switch has to be able to ground to the block when it is screwed in, and the tape is preventing that.
Drain your coolant, take the tape off, and screw it back into the block tightly, but don't break it. The body of the switch is brass, so it should conform and not leak. I had a simular problem after I rebiult my engine, but my switch refused to ground due to new engine paint all over the threads - which BTW - are almost impossible to clean when the engine is in!! The only way I could fix mine since I refuse to pull an engine to clean sensor holes, was to buy an aftermarket kit with a sensor that goes in the radiator fins - and it worked gret till today when the relay decided it did'nt want to play anymore. Anyway - Good Luck!!

------------------
-1983 L69 Camaro Z28 305 H.O. (Bored .030 over,Teflon oil seals,Melling oil pump,Hyperetic pistons,chrome-moly rings,2040 Crane compu-cam) T-tops, 3:73 Open rear, BW T-5, Rebuilt E4ME 4 Barrel, Duel Snorkle, Rhino Clutch, 2040 Compu-cam, LS1 valve springs, porting, PST front end kit with new springs, K&N Filter and runs great but ain't streetable yet!!....Future Mods: JUNK IT if this keeps up!!

 

99% liklihood the teflon tape is your problem
in this case.
God bless ya.
Chuck

 

Yeah I think/hope the teflon tape is whats causing the problem.......Im going to have a LONG day at school tomorrow.......so I'll either do it friday or saturday. Wish me luck.....if it still doesnt work Im going to set that fan switch on fire.

------------------
http://users.ticnet.com/mult68
1992 Teal Camaro RS
T-Tops
305 TBI V8
Open air element
3" Flowmaster Exhaust System w/Quad Tips
Aiwa CD/Mp3 player
10 Disc CD Changer
Rockford Fosgate Speakers
SLP Headers Coming
Dynomax High Flow Cat Coming
More to come.

 

Having the same problem. But in my case, I had to replace the radiator cause it started leaking, ever since then, the fan wont come on. Not to ask a stupid question, but can someone tell me the exact location of the sensor unit on a 88 Formula Tbi. It looks like a sensing unit is on the new radiator ( guessing cause its a new model? but no wire to connect it to ) Also will this affect my temp gauge cause that aint working either.

 

The stock eprom is your problem. The stock eprom does not engage the fan until 228*F and then stops aroun 220*F. The most effective cure is to get the eprom altered to engage the fan to come on sooner.

This is especially necessary if you switch to a cooler T-stat.

 

You could use an ohmmeter to check for continuity between the shell of the fan switch and the head casting... sounds to me like that's where the problem lies. If you can ground the wire and make the fan come on, then the wire, relay, fusible link, fan motor, etc. etc. are all OK.

You could just be lazy like me and tighten up the fan switch a turn or 2. I believe that's what I'd do first, since I hate work so much. You can do that with a deep well socket in a matter of seconds, and that might be all it needs.

------------------
"So many Mustangs, so little time..."
ICON Motorsports