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**VetteVet** · 01-10-2017, 03:37 AM

The relationship between voltage and amperage is directly proportional i.e. as the voltage goes up the amperage goes up provided the resistance stays the same.
If your alternator is overcharging then the amps through the fuse will increase and blow the fuse. Check the voltage at the alternator with the truck running and place the fan on high to bypass the heater resistor. This will give you the maximum current flow through the fuse.

The relationship between resistance and amperage is indirectly proportional i.e. as the resistance goes down the amperage goes up and vice-versa, provided the voltage stays the same.

The heater fuse is rated at 10 amps so you shouldn't be drawing near that much normally.

01-10-2017, 03:37 AM	#5
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,725	Re: heater fuse blows when truck is running The relationship between voltage and amperage is directly proportional i.e. as the voltage goes up the amperage goes up provided the resistance stays the same. If your alternator is overcharging then the amps through the fuse will increase and blow the fuse. Check the voltage at the alternator with the truck running and place the fan on high to bypass the heater resistor. This will give you the maximum current flow through the fuse. The relationship between resistance and amperage is indirectly proportional i.e. as the resistance goes down the amperage goes up and vice-versa, provided the voltage stays the same. The heater fuse is rated at 10 amps so you shouldn't be drawing near that much normally. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.