Radiator fan ON blows fuse

[KalamazooJohnny]

Only been driving it now a short time, and only on short sprints. Has been pushing toward overheating, and I don't think the fan has been kicking on at all. I have a brand new fan switch in the bottom of the radiator, which I installed, so I was thinking maybe I didn't get the air bubbles out of the system when I put that in. So I decided to remedy that and while I was at it, I put in a new thermostat, and both temp sensors atop the engine. I CHECKED THE FAN TO MAKE SURE IT WAS WORKING BY JUMPING PAST THE NEW RADIATOR SWITCH I HAD PUT IN. When I put the jumper in to bypass the switch, the fan immediately came on, and I let it run for a few seconds. I actually did this twice. I do not believe the car was running though when I did the bypass test. So I got everything back together and refilled the coolant as properly as I could follow directions, front of the car up, even installed a T in the heater hose to make sure I got the air out, started the car and let it run, the thermostat must have opened because I felt the bottom hose get warm, the temp gage went up past middle and the fan actually kicked on as is should, but it only ran for about 5 seconds, then blew a fuse. OF COURSE, I put in a 16 amp fuse when the 8 amp blew, and everything worked fine after that. Only problem, I don't want that 16 amp fuse in there when there is suppose to be only an 8 amp. Can anyone comment or make suggestions as to where I should focus now? Thanks.

[spider2081]

My wire diagram for an 81 Spider shows fuse 10 (L) for the fan and that it is a 16 amp fuse. So I believe you are safe and now have the correct value in your car. I have tested these fans with a power supply and normal operation current with fan blades attached to the motor does exceed 8 amps. That is why the connections in this circuit are so prone to failure and intermittents . The push terminals used at the fuse panel and elsewhere in the circuit break down in time from the high current flow.

[KalamazooJohnny]

Made me look at wiring, and now am more confused. My spider is a 77. Sorry I did not mention that before. My owners manual says the fan is on fuse "A" which should be 25 amps, but the fuse that is blowing is fuse "I" which the owners manual says should be 8 amps. But, according to the wiring diagram I am looking at (by Brad Artigue) the fan is on fuse "I" which is the one that is blowing, so I believe my wiring matches Brads diagram, but what is the correct fuse size for fuse "I" ? Anyone?

[dmwhiteoak]

It sounds like you have a short somewhere. Something is going to ground, either a bare wire or the fan moter.

[vandor]

.... but what is the correct fuse size for fuse "I" ? Anyone?

If the fan is on that fuse, then it must be 16A.

[KalamazooJohnny]

I am just finding it hard to believe that the owners manual is so blatently wrong. I guess I will just leave the 16amp fuse in there. Maybe today I will try to honk the horn while the fan is running and see what happens.