New Heater Motor-Blown Fuses

[Short 3/4]

I recently replaced the original heater motor on my Thrift-Air 65 heater with a new one from the local parts store. I knew I should have been suspicious when they had one on the shelf. Fit right in, and boy does it blow a lot more air than before. Unfortunately after about a minute on high it blows the 10 amp fuse. Turns out the new motor draws just north of 15 amps. Obviously for a newer model truck, probably with AC. Now I know plenty would just pop in a 20 amp, or even wrap the old one in foil, but as an old electrician who spent a lot of his career as a troubleshooter, I know that won't end well. Figure I have a few options:

-Never use high. Hard to do now that I have that ultra high speed it never had before.
-Rip out the new motor and try to find the right one. Again, giving up that new high speed.
-Put in a relay. I hate the thought of cutting up my brand new under-dash harness.

Any other ideas? I can't be the only one out there with this problem, what have others done?

Appreciate any help,
Tom

[bhap]

Figure out if the wiring to the motor is sufficient to handle 20 amps - how long and what gauge wire to motor from fuse box - and if your system has capacity (alternator or generator?) and if the juice is available, use the 20 amp fuse. There's a difference between just throwing in a bigger fuse and knowing what you are doing will work.

[AcampoDave]

I would go with your second option. A stock fan on high blows plenty hard enough and the fact that the one you have is even faster makes me think something is wrong.

[theastronaut]

My old '69 C10 did that when I installed a new blower motor. If the wiring and switch is in good shape and sized so it can handle the extra amps, then it won't hurt to install a 20 amp fuse. The switch might be a weak point.

[Short 3/4]

Unfortunately can't verify the wire size. Factory literature shows sizes of all the wires except for optional equipment. Besides the wire size though, the other weak links in the system are connections and, as stated above, the switch. Running full power through a switch designed for 10 amps would probably not do it any good in the long run.
So, even though my wife really really likes that extra blast of warm air on her feet on cold mornings, I think I'm going to stop using high speed until I can find the correct motor (any shopping tips?)
Thanks to all that took the time to help me out,
Tom

[val1gonzales]

What about adding a 40A relay powered by the heater switch and wiring relay with its own power wire to the motor. 4 pin 12v
https://www.amazon.com/Ehdis-Relay-4...835828547&th=1

[ACK]

If I'm reading right, this is the blower motor for your '65 on Amazon, cost is $24 ... LINK. You can cross reference the part number with SummitRacing.com or other vendor to confirm it's whats needed and you should be good to go.

[Short 3/4]

Yes, the correct way to solve this problem is with a relay, that’s what the factory did in later years, unfortunately I really don’t want to cut my brand new harness. Looks like a really good price on the replacement and looks like it’s the right one. Will research that source more and probably go that direction.
Thanks for all the help
Tom