There is an inexpensive alternative to replacing the original heater motor, although I wouldn’t necessarily favor it unless cost is critical. If you can’t get the old fan off the old motor, replacing both can add up quickly:
http://www.classicparts.com/1947-63-1964-66-w_Air-Heater-Motor-12-Volt/productinfo/68-009/http://www.classicparts.com/1960-72-Heater-Fan-With-or-w_o-A_C/productinfo/68-061/On my recirculating heater I replaced both the blower motor & fan with components from a Pontiac Fiero. The original use of the Fiero fan & motor happened when I was running an aftermarket heater/air conditioner. Twice the fan motor burned up for no apparent reason (under warranty) filling the cab with smoke. After the second time I wasn’t interested in a warranty replacement and started looking for a GM substitute. The Fiero (and I believe the S10 pickup) both had heater motors that turned in the proper direction. Fiero heater motors live inside the trunk so they all look like new. I bought two of them ($5 each including the fan) at the local pick your part. The first one was working perfectly when I pulled and discarded the A/C system. So when I obtained an original recirculating heater with a dead motor, I just swapped in the Fiero motor. The spare Fiero motor remains in the basement should I need a replacement some day.
I believe I used some of the original mounting plate from the factory heater motor, along with some minor trimming, and it fit perfectly. The Fiero also has a plastic fan with a stronger pitch so it really moves a lot of air. It’s also a permanent magnet type so it’s more powerful. Eventually I’m going to run a relay on the high speed circuit, but it’s been working fine for many years the way it is.
Here’s a picture of the finished install taken through the glove box opening. (The box in the upper left is my cruise control module, not part of the heater). The rubber hose is a vent for the motor. I don’t remember what it connected to in the Pontiac, on mine I just left it resting as shown. Should you have a bit of creativity and a local source for a junk Fiero, this is a cheap workable alternative.
[IMG]http://img254.imageshack.us/img254/2381/fieromotor.jpg[/IMG]