when i replace the 30 amp heater fuse in the dash area and turn the heater on the the fuse glows orange in seconds then blows, where do i start to fix this, maybe at the fan switch, 94 F350 box truck

 

I would start at the heater fan motor; the circuit breaker/fuse blowing is telling you something in that circuit is drawing more power than it should be, and I believe that fan motor is the only thing in that circuit.

Does the motor turn easily by hand? If not, this very well could be your problem....

 

I'll second that!!!!

 

i can't get at it until monday but that's a good start i was thinking the switch

 

the blower motor was totally seized thanks for the suggestion on where to start looking guys

 

Thanks for the update, glad you got it figured out.