Heater

[pjmoreland]

Originally Posted by Frogurt

I forgot to say, when I don't have the truck running and it is just on accessory it will work on high forever but as soon as I start the truck it blows the fuse.

The alternator raises the system voltage. Higher voltage results in more current to the blower. Your 10A fuse must be right on the edge of working on 12.5V battery voltage, and the slight increase in current when you've started the engine is enough to push it over the edge at 14.5V.

[dmjlambert]

If I had a non-A/C truck and all I could find is A/C blower motors (I think that is the case) I would add another resistor in series with the motor to reduce its speed and make its top speed similar to a heater blower motor. This would help preserve the fan speed switch and wiring. Until that is done, run it on low or medium only. The additional resistor should be located inside the heater box so it gets cooled off by air flow, because it's going to get red-hot.

If you happen to have the original heater blower motor, I suggest take it apart and see about replacing the bearings and get it going again. I have replaced bearings on small blower motors on a B-52 and it worked out fine. Perhaps that same thing can be done on a Chevy.

[HO455]

Originally Posted by dmjlambert

If I had a non-A/C truck and all I could find is A/C blower motors (I think that is the case) I would add another resistor in series with the motor to reduce its speed and make its top speed similar to a heater blower motor. This would help preserve the fan speed switch and wiring. Until that is done, run it on low or medium only. The additional resistor should be located inside the heater box so it gets cooled off by air flow, because it's going to get red-hot.

If you happen to have the original heater blower motor, I suggest take it apart and see about replacing the bearings and get it going again. I have replaced bearings on small blower motors on a B-52 and it worked out fine. Perhaps that same thing can be done on a Chevy.

Personally before going through the work of adding a resistor to the circuit (which adds to the total circuit draw if the resistor is in series with the motor and factory resistors) I would either get the correct blower motor (https://www.napaonline.com/en/p/TEM9...pressionRank=2 ) or wire a relay in the circuit like the factory did for AC vehicles. Here is a link to what I did scroll to post 871 and continued on the following page.

http://67-72chevytrucks.com/vboard/s...698377&page=35

I will point out many folks have simply found that replacing the 10 amp fuse with a larger fuse has worked for them after installing an AC blower.