For some reason that I just don't understand my fan no longer works. I disconnected the wires and gave it power and it works so I know it is not the fan motor. So which sensor runs my fan? I know that I broke off a sensor in the block by the starter putting on my headers but someone told me that it was my knock sensor and ever since then my fan is a waste of weight. Surely that does not controll the fan! Can anyone help? Thanks

Eric

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Teal 1991 Camaro R.S., T-Tops,
Leather, Re-worked 700r4 also w/kit,
MSD ignition, MSD 8.5 mm. superconductor wires,
MSD Coil, ADS superchip, Open element air cleaner,
K-n-N filter, Gutted cat, Flowmaster cat-back system,
Edelbrock TES headers, March 3piece billet underdrive pulleys
3.73 gears
http://www.geocities.com/gitarz2/camaro.html
I was shocked to see that companies sold a taillight
set for a rustang! Since when do they have taillights????

 

Speaking in terms of an '88 IROC with A/C, the driver side fan is controlled by the temperature sensor. This sensor is under the throttle body on the driver side front. There are 2 wires there, I think Yellow and Black. It's supposed to turn the fans on at 190*.

The heavy duty fan is controlled by a few things, like having the AC on, but is ultimately turned on by the coolant temperature switch. The switch is on the passenger side of the block, between and below the 3rd and 4th exhaust ports.

On my car, I installed a temperature switch (on the block) that comes on at 210* and goes off at 185*. I wired it to the 2nd fan, which causes both fans to come on when it trips. I took the AC out, so I wanted both fans on when it was time to cool down.

My temperature sensor tests fine, I ran all the ohm tests at various temps, but my fan wasn't coming on either, so I rewired things.

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Michael Bangert
mbanger@iupui.edu
'88 5.7 IROC
'99 CBR1100XX
'00 Silverado LT

[This message has been edited by tregnab (edited March 23, 2001).]

 

The fan's temp switch is in the pass side head between the #6 and #8 spark plugs. Check to be sure the wire is plugged in. If you ground the wire, the fan should come on. If it doesn't, check the fan relay which is between the master cylinder and the left fender. If it does, replace the switch.

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

 

The one between the third and fourth exhaust port is the one that I broke. Someone told me that it is the knock sensor but I did not think that it was. It has been broken off for a while now and the car has run fine. (other than hot) I broke off the sensor and the connector from the ecm. That is why it is not fixed because it is going to be a pain in the butt. If that is truly it then there is my problem. Thanks a lot.

Eric

 

The info you'll get here is usually alot more accurate than "someone"...

The knock sensor is at the very bottom of the block about ½" above the oil pan rail on the pass side, about even with the end of the starter. It also serves as the coolant drain plug for that bank.

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

 

Actualy the sad part is that it was someone here that told me that. I was even told in fact by the same person that there was NO other sensor on the block period let alone the passenger side. Only the knock sensor...hummm...isn't that funny. Tell that to my broken sensor. Thanks for the help. It is greatly appreciated.

Eric

 

It's not that hard to replace if you put the front wheels on a ramp and do it from underneath. There is plenty of room for a box wrench.

Have the new one in hand ready to throw in there as soon as you pull the old one out, and don't wear your favorite shirt because some antifreeze is going to run down your arm for a few seconds.

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Michael Bangert
mbanger@iupui.edu
'88 5.7 IROC
'99 CBR1100XX
'00 Silverado LT

 

Eric,

Whoever told you that might have been correct - depending on which year, engine, and fuel system you have. There were a lot of variations over the years and between models, so the information you got might have been completely correct for a particular year and engine.

That's just another reason it is always important to be clear about what year/model/engine/fuel system/modifications you are asking about. From your signature, I'd presume that you have a TBI 305, but that might not be correct.

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader

 

Vader. Good point. I forgot that all models and fuel systems are different from the others. I thought it said in my sig but I guess not. (305 TBI) I am pretty sure that mine is the fan switch that I broke and need. Correct?

Eric

 

Now there is a 3 second heasitation when I hit the gas...could this broken switch cause this? Please help.
thanks

Eric