muskrat51

I have replaced engine coolant temp unit and gauge sending unit and the fan relay and the fan will not come on when she heats up. the fan comes on when the ac is turned on. any ideas???

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camaronewbie

fan switch - pass side head between #6 & #8 cylinder. remove the connector, and with key on, ground it - if fan comes on, then the switch is bad. watch eyes/face when replacing, coolant comes out there!

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1992 25th Anniversary RS
350 Edelbrock 1406 Carb
10:1 Dometops Mild Cam
Hedmann Coated Headers
Hi-Flo Cat/Aerochamber Muffler
Rebuilt 700R4 B&M Shift Kit Vette Servo
LS1 Disc Rear w/3.42 Posi
Poly Bushings
Eibach Prokit
Bilstein Shocks/Struts
HOK Candy Teal on Silver Flake

1997 Camaro Z-28 LT1

BigBadLou

Without knowing what engine you have, we cannot give you any answers (no matter how much we'd love to guess).
TBI/TPI? Year?

To save yourself trouble of repeating this information in every post, simply fill out your profile with your car's info.

Lou

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'91 Z28 convertible w/305TPI WC T5 (no more auto)
"Nothing screams more of poor craftsmanship than wrinkles in your duct tape!"

bcfipp

It is my dads car. He has a 1991 camaro rs. It has the tpi v6. I believe it is the 3.1.

BigBadLou

Not sure if you are the original poster (two different user names) but the posts sounds like it. *shrug*

Anyway, on the V6 MPFI engines, there is no overheat switch in the passenger side head. The ECM is the only thing that controls the fan on this engine.

If the A/C turns the fan on, that means that the fan circuit functions correctly all the way from the ECM to the fan.

What temperature did you let it heat up to? The ECM is programmed to kick the fan on at 238 degrees Farenheit, if my memory serves me right. So yes, your dash gauge should be showing 240 for the fan to kick in. If it gets to 250 and still nothing, I'd check the actual engine temperature with an infra thermometer. At that point, I'd also ohm out the coolant temp sensors (both, for the ECM and for the dash gauge).

Let us know.
Lou

__________________
'91 Z28 convertible w/305TPI WC T5 (no more auto)
"Nothing screams more of poor craftsmanship than wrinkles in your duct tape!"

muskrat51

I replaced the coolant temp sensor under the nose of the throttlebody and the gauge sensor on the pass. side of block, and also the fan relay on the firewall.

BigBadLou

How hot did you let the engine get?

Lou

__________________
'91 Z28 convertible w/305TPI WC T5 (no more auto)
"Nothing screams more of poor craftsmanship than wrinkles in your duct tape!"

muskrat51

I t seems the temp gauge goes all the way to the red zone. had it checked by a mechanic and said that the gauge was goo but sensor was bad

muskrat51

I just bought this car two months ago and can't get used to the high temps these thing run at

BigBadLou

Hmm, at this point, I'd put a laptop on the ECM and check that it reads the engine temperature correctly and sets the fan request as needed.

Is the engine harness hacked up in any way? Previous owners do stupid things with our cars.

Lou

__________________
'91 Z28 convertible w/305TPI WC T5 (no more auto)
"Nothing screams more of poor craftsmanship than wrinkles in your duct tape!"

muskrat51

no car was owned by a 48 yo women that was the original owner. that is the only thing that I can think might be wrong something in the wiring.