Essentially, my car tells me when I deserve to have the fan on...
It's kind of odd. First, the switch for high, medium, etc, does not directly control the fan. Also, I know my fan works perfectly fine, because sometimes, it will just turn on, really strong. I've found that, GENERALLY, If I turn the car on, turn the fan switch to full, within 15 minutes, it will come on. Sometimes it just doesn't. Also, sometimes If I turn it off, it still doesn't want to agree...
I would assume this is just a wiring issue, but the fact that on rare occasions, it will perform like normal.
Any thoughts while the car is disassembled?

 

You could just wire it so it runs all the time like mine. As soon as you turn the key on it starts running.

 

More than likely the problem is in your resistor block for your blower speeds. GM has had issues with them for years and still has them. the resistor is located next to the blower motor and will have two connectors, one that has two wires that goes directly to your fan motor, and another with 4 wires that connects to your blower switch and the fuse block. If you want to test, next time the fan will not come on check with a test light across your fan connector if the light does not come on you've got no power, check back to your resistor and check for power and ground more than likely you have both going into the resistor and are losing one before it makes it to the fan. Resistors of that style are fairly cheap and can be picked up at any auto parts store, or the dealer.

 

Check the fan motor grounding wiring that goes to the back of the passenger cylinder head. Sometimes it gets loose, frayed or otherwise has a poor connection. When I had this problem the wire would make/break contact depending on where the motor was swinging from the torque. I simply ran a secondary ground wire [which is still there after two years...]

 

if everything you have been told so far checks out, the fan motor may be dying. next time it does it, open the hood & tap on the fan motor with a screw driver, if it starts running replace the motor.

 

My fan did the same thing when the switch broke, I got a used switch off of a junk car, works right now.

 

Al right, thank you all, I'll check these things out tomorrow night.

Oh, one thing. Where is the Blower motor? Under the dash pad?

 

Your blower motor is mounted on the passeger side of the firewall.Look on the far lbetween the passenger fender and the receiver/dryer.You'll probably find a lot of leaves and pinestraw in there.And don't be surprised if it's home to a small furry 4 legged friend.

 

This isn't an F-Body,obviously,but it gives a better idea of the blower placement than the other pic I posted.It's behind the SPID on the fender.Has 7 to 10 7MM retainer bolts

 

I like my relatives, but they'll sure impede car progress...

I just took this picture, it's the big black thing on the very left, right?
Can you see the resiistor block in here? ANd, it the ground the black wire that's kind of clipped on?

 

I think I found the resister block.. It's the rectangular cubic thing above the green clip in my picture, right?

EDIT: I don't have a test light, but I do have a digital multi-meter... What kind of voltage/amps should it be getting on hi?

 

ok, more info... I've got the relay thing off, and I used a multimeter to test resitance..

It's got prongs in this shape:


1 _
2 _
| |

5 _


3 and 4 are the two verticle ones..

I get no resistance between 5 and 4, and no resistance between 2 and 3.. Per my memory anyway..
Should that be what's going on, or is it blown?