I am having problems with my cooling fan coming on. It will not turn on by itself unless the Air Conditioning is turned on. Reading through the threads here seems to indicate a bad fan relay. Where is this relay located? I thought i read that its on the cylinder head below the exhaust manifold. What is the quickest way to get to this? Pics provided would be great. I have a Haynes manual, but I cannot find this topic anywhere in the manual.

 

UPDATE:

I wento t advance auto parts store to order a new relay. However, I'm not sure the one they gave me is correct. By the descriptions I've seen here, the fan relay is on the engine block. I jacked up the passenger front side ofthe car and crawled under. I never found anything in the way of a relay. Crawling back out and looking around I found a match for the relay in hand and it turned out to be a relay mounted on the firewall in the very corner of the driver's side area of the firewall. Is this correct< or what relay did I replace?

Also, replacing the relay did not fix the problem. Fan does not come on unless air conditioning is turned on.

Any ideas on what I should do next? I'll go ahead and run a toggle switch if there's no other solution. What's the easiest way to run a toggle switch? Just tap into the fan motor plug, or can I tap into the ALDL and how???

 

The relay is up, with a couple others, on the firewall. The sensor for the ECM which tell the relay when to close to engge the fans is under the exh. manifold around the #6 cyl., it has one wire going to it.

I'm having almost the same problem right now, except my fans turned on sometimes (fans where not turning on, turned the car off and back on and the fans ran ). I've tried changing the enable disable temps in the ECM (by buring a new chip), no help.

I'm going to make a post over at camaroZ28.com to see if someone can help.

 

Then chances are, I did replace the relay. However, it has not solved my problems. Worse yet, even with the air conditioner on, my car is running hot. It holds a temperature at 240 degrees (the middle line between 220 and 260).

What else should I consider?

 

If the fan comes on with the AC, then your relay is WORKING. More than likely, you have a temp switch in the passenger side head between the two center spark plugs. This switch (looks like a temp gauge sending unit with round plug) grounds the relay and turns on the fan at a preset temp. It is not computer controlled. Other models (like TPI) have computer controlled fan(s), and will not have this switch unless it is for a secondary fan.

Check and make sure that the wire is connected to the switch. You can disconnect the wire and ground it to something with the key on and the fan should turn on. If the fan does not turn on, something else is going on. If the fan DOES turn on, then replace that switch. NOTE: Factory switch will not turn on the fans until 225* So if you want it to turn on before that, you will need to find a different temp switch.

On another note: Are you getting your readings from your stock temp gauge, because they are notoriously wrong. Verify your actual temp by plugging in a scanner and see what the ECM thinks the temp is (uses a different sensor).

 

Fan Switch part numbers:

FS6 - Closes at 204*-220* F- Retail $21.59

FS4 - Closes at 211*-227* F- Retail $8.69

FS1 - Closes at 222*-238* F- Retail $9.49

FS3 - Closes at 240*-252* F- Who would buy this one??

or:
http://www.madvet.com/shop?frame=3.138.944

 

Have wires and toggle switch to manually turn the fan on, but not sure this will solve my problems.

Car is being run with A/C running on Max. Car overheats while drivingfor 20-25 minutes. At long stop lights, or just stopped period, the car begins cooling down, almost immediately. You can watch the gage needle begin moving back downwards. Sitting still and idling for about 5 minutes and the engine will cool back to 220 degrees or lower.

Is the air conditioning periodically turning the fan off and on as the cmpressor cycles or is there another issue to consider?

 

Okay, have you checked to make sure the lower front air dam is on the car and not broken? That piece directs air up into the radiator while driving.
How old is your water pump? If the impellor blades are shot, then you may not get adequate cooant flow as the engine speed increases.
The only other thing I can think of at 3 in the morning, is that the fan motor might be getting weak from age, and slowing as the air pushes against it.
Your fan should be on the entire time the AC is on. Is your compressor cycling on and off like it should?
BTW if your fan is coming on when you turn on the AC, I don't think it is a relay problem, but a problem with the sensor that is in the passenger side head. Use that list of part numbers to get the switch you want from your local auto parts store, or follow the link I provided to purchase one online. You will need to drain your coolant in order to replace this sensor. With my factory sensor, the fan would only come on after it read 240º, and even then it would only stay on for a few seconds.
I just clipped the green wire that runs to the sensor and put it to ground, so that the fan comes on and stays on, until I turn the car off. Temps never go over 200º, even with undercharged AC on max. Of course I will have to change this back in the winter and or emissions time

 

Overheating while driving is either from not having an air damn or what is most likely your problem the radiator........It sounds like you need to flush it or if your wallet will permit it get an aluminum one from summit for $180.

 

Well, you guys are correct, there is no air dam on my car. The bolt holes were rounded out until they broke. So I took it off. That was over a year ago and I never had problems overheating.

I may just clip off the sensor wire and ground it and see what happens. SO far it seems okay now that the weather has died down. I've taken to modulating the air conditioning to regulate engine temps. I leave the A/C off and drive until the temp hits 20-220. Then I turn the A/C on and it cools down to 190 or so. I leave the A/C on if I'm in heavy traffic and then turn it off when I'm at highway speeds (unless of course its bumper to bumper highway speeds).

Its a bit crude I know, but its working so far.

 

I was doing that AC trick for a little while too. Then I just used that grounding the wire trick to start the fan everytime the ignition is on. You could also just use the wire at it's source, the relay. That is basically how you make a manual fan switch. Tap into the green wire of the relay and run it to a switch inside the car. I also have Willie's instructions on how to do that, if you want it. I converted the file from PDF to Word, also. PM me with your email if you want me to send it to you.
Oh yeah, here's a diagram I found on this board that labels the relay wires.
Thanks to whoever originally posted this info

 

Thanks!

Yeah, I was pretty much going to just ground the green wire out of the relay. That way I don't have to crawl under the car to find the temp switch.