Hi guys, I'm a new member and I have a problem with my heater.

I have a 91 S-10 Blazer and the heater fuse keeps blowing while I'm driving. Sometimes it'll last for weeks and sometimes only for minutes. I actually thought I had this fixed when I replaced the switch in the dash a month ago (not the hi - lo speed switch, but the one that controls the defrost / heat / AC settings) but it reared it's ugly head again today. It blew the fuse just as I was getting to work, so I replaced it at lunchtime, but it blew again just as I was getting home (a roughly 15 minute drive).

It seems to occur when accelerating, so I'm thinking maybe the internal resistor in the alternator when the engine revs?

It may also have to do with the vehicle being inclined. Where I work is on top of a hill, and you have to stop at a stop sign part way up. Before I replaced the switch a month ago it blew two days in a row in the same spot when starting to accelerate up the hill. Would bad (loose) bearings in the heater motor cause the motor to short if the vehicle is inclined?

Thanks in advance for any help, as I'm not real good with electrical stuff.

 

The heater fuse only deals with the blower motor. It feeds into the switch, then to the blower motor resistor, and off to the blower motor.

Here's a diagram for you that is somewhat generic, but applies:

 

sunds like a bad blower motor,,,,