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fan only coming on when the hvac unit is used

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Old Jan 3, 2009 | 08:09 PM
  #1  
venom204's Avatar
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From: Sacramento, CA
Car: 91 Camaro RS
Engine: 305 TBI
Transmission: Auto
Axle/Gears: 2.73
fan only coming on when the hvac unit is used

Ive replaced the water temp sensor (next to thermostat) and right between the 1st and 2nd spark plug on the right there is my fan relay switch that i also replaced. Thing is the fan still does not come on after letting it warm up. The previous owner did run a wire from a switch to the fan and added his wire into the fan and power wires next to the battery. He says he left all the orig wires intact all i gotta do is pull the wires off. Anyone have an idea?

Thanks

*Edit* One thing i might add is that after fixing the water temp sensor the gauge started to work, when i let it sit the gauge gets to about 160 degrees and stays. The fan turns on after about 220 right?

Last edited by venom204; Jan 3, 2009 at 08:14 PM.
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Old Jan 15, 2009 | 12:17 PM
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84 1LE's Avatar
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From: Oyth
Car: 89RS vert
Engine: Erod
Transmission: 4L65e
Axle/Gears: BW, 3.27
Re: fan only coming on when the hvac unit is used

The temp switch by the thermo housing is for the computer, not the gauge or fan.The sensor for the gauge is on the Dr. side cylinder head.Between the first two exhaust ports.The switch for the cooling fan is on the pass. side cylinder head between the lasttwo spark plugs.All that extra wiring could also be an issue!
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Old Jan 15, 2009 | 03:20 PM
  #3  
venom204's Avatar
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From: Sacramento, CA
Car: 91 Camaro RS
Engine: 305 TBI
Transmission: Auto
Axle/Gears: 2.73
Re: fan only coming on when the hvac unit is used

dang lol i was looking for that answer for along time lol i just resently found out that it was indeed the fan switch on the pass side head which i did not know was there, its broken off at the connector. What would be the best way to get it changed out? From the bottom of the engine? ive got the part coming and trying to figure out how to get it changed its so tight of a spot from the top.

Thanks
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Old Jan 15, 2009 | 03:49 PM
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84 1LE's Avatar
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From: Oyth
Car: 89RS vert
Engine: Erod
Transmission: 4L65e
Axle/Gears: BW, 3.27
Re: fan only coming on when the hvac unit is used

If you have headers, probably from under the car.Ex manifolds, should be able to replace from the top.
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Old Jan 15, 2009 | 04:06 PM
  #5  
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From: Sacramento, CA
Car: 91 Camaro RS
Engine: 305 TBI
Transmission: Auto
Axle/Gears: 2.73
Re: fan only coming on when the hvac unit is used

awsome thanks for the help
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Old Jan 16, 2009 | 11:27 AM
  #6  
iroc a 86 berli's Avatar
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From: south of kansas city
Car: 86 berlinetta 92rs gfx
Engine: 4 bolt 384 stroker
Transmission: th350 4000 stall manual/T brake
Axle/Gears: 87 iroc 9 bolt
Re: fan only coming on when the hvac unit is used

incase your wondering why it only works with hvac activated, its because there is a temp overide when the a/c is on to cool the condensor.
other then that it should cycle when temps hit around 200
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Old Jan 26, 2009 | 11:41 PM
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From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: fan only coming on when the hvac unit is used

If you don't want to pull your headers, you'll at least need to pull the Ypipe...its' a tight fit. I also suggest draining your coolant or you'll get soaked. If you can, get a Jet Fan switch, turns on cooler than the stock fan and will help keep things cool. Best of luck to you! Oh, one more thing, make sure you use teflon tape and make it tight...learned that one the hard way. hehe
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Old Feb 7, 2009 | 08:09 PM
  #8  
camaronewbie's Avatar
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From: Cary, North Carolina
Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: fan only coming on when the hvac unit is used

Originally Posted by Ozz1967
make sure you use teflon tape and make it tight...learned that one the hard way. hehe

NEGATIVE NEGATIVE NEGATIVE

NO TEFLON TAPE!!!!!!!!!!!!!

The fan switch has a single wire to it - the switch itself must ground to the head, otherwise the circuit will not be complete and the switch will NOT work! Teflon tape will inhibit the ground - NO TAPE - just install it!
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Old Feb 7, 2009 | 09:00 PM
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From: St. Cloud, MN
Car: 1984 Trans Am
Engine: LS1383 in work
Transmission: Magnum F - to be installed
Axle/Gears: Zexel Torsen 3.73, 28-spline mosers
Re: fan only coming on when the hvac unit is used

Originally Posted by camaronewbie
NEGATIVE NEGATIVE NEGATIVE

NO TEFLON TAPE!!!!!!!!!!!!!

The fan switch has a single wire to it - the switch itself must ground to the head, otherwise the circuit will not be complete and the switch will NOT work! Teflon tape will inhibit the ground - NO TAPE - just install it!
When installed mine the first time without teflon tape, it leaked...wouldn't seal properly. I had to use the tape to stop it from leaking coolant.
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