My 20 amp coolant fan fuse keeps blowing when I turn the key to the 'ON' position. I have checked the wiring diagrams in the Haynes repair manual to figure out what happens when I turn the key to ON and how that relates to the the circuit that includes the fan fuse. I'm thinking that I have a short somewhere but not sure where to start looking. Any ideas on this problem?

 

That circuit goes to the cooling fan relay and pin "F" on the alternator.
Unless someone removed the fan relay and tried to power the fan directly it's unlikely that the relay is shorted and causing the fuse to blow.
Check the alternator by unplugging it and see if the fuse still blows.
If it doesn't, it's the alternator.
If it does, and the relay wiring hasn't been molested, replace the fan relay.

 

Supervisor42 -
I had replaced the alternator and battery in an effort to resolve the orginal problem I had of the battery not charging and the coolant fan was not running. I determined that the cuase was a blown coolant fan fuse which I had overlooked. I replaced the fan fuse, started the car and the alternator was now charging the battery properly and the coolant fan now worked when I turned the AC on. I figured the problem was solved. After driving the car for about 200 yards, the battery was no longer charging and and an inspection of the fan fuse revealed it was blown again. I replaced the fuse once more and started the car and the battery was again charging however, as soon as I closed the hood, the fan fuse blew again. At this point I figured that there must be a damaged component or short in cooling fan/charging circuit. I tested the coolant fan by applying 12 volts directly to it and it worked fine. I also removed the fan relay and applied 12 volts directly to it and it also switched correctly.
To try to isolate the problem I have
1. Disconnected the 3-wire connector from the alternator
2. Disconnected the connector at the cooling fan
3. Replaced the cooling fan relay

When I turn the key to the 'ON' position, the fan fuse immediately blows!

I have not yet disconected the cooling fan relay to see if the fuse still blows but I'll try that next. I can't imagine that harnessed wires would suddenly develop shorts in them but unless I'm missing something that's obvious, I will have to trace both wires connected to the fan fuse and see what the heck is going on.

 

Wait you said you closed the hood and the fuse blew right away, doesnt that indicate that the wire is grounding out somehere? most likely passing thru the firewall?. i had a similar problem that i couldnt trace, i would put in a fuse for the digital dash and as soon as i would push the fusebox up into place it would blow, so i traced the wire from that particular fuse that was blowing and surely it was resting against a sharp edge and it got frayed so when i pushed the box up the wire moved up till it grounded out on the frayed part. i think i rather blow the engine than have an electrical problem. grrr....