I do not know for sure on the 65, but on a 66, the blower has two wires, and one goes directly to power, all the time,  The second one is a ground wire and, depending on which resistor is connected by the switch, you either get HIGH (no resistance in the ground circuit) MEDIUM (some resistance) or LOW (highest resistance).  You have to have those two resistors to make all three speeds work.  If you just want HIGH and LESS THAN HIGH you can run it through just one of the resistors on the side of the heater case.

I want to be able to use the blower on more than 1 speed without having to change the blower motor

MS I guess I would need to order a 66 resistor then???

Early 1965
Smooth heater box no resistor
Three wire blower motor
Switch has off in the middle with high and low only
Special under dash harness

Late 1965 and 1966
Resistor in the heater box
Two wire blower motor
Switch has off to the left
Wiring harness has a branch wire for plug at resistor

What I have is a late model 65 blower in a early 65 model!!  anyone have an Idea how to make this work? I really don't want to rip the heater box out to replace the fan motor!!  It has worked on one speed for 6 years but would like it to aork on both!!

Terry, don't know if this will help. Not sure how the 2 speed switch was connected. Never seen a wiring diagram with a 3 wire motor. But maybe you can try something like this. You could get a resister pack and use one of the resisters, Doesn't matter which one, which ever speed works for you. Keep in mind if you don't mount theresister pack in the heater box, it gets quite warm.

Last edited by wsinsle (2/14/2015 10:17 AM)

walt.  This is a 64 mustang schematic ( didn't know they made one LOL)  but this is how my car is wired!! I have a 2 wire motor in there and I have the ground wire on the motor to ground on the firewall and I think I have the orange wire from the switch wired to the hot on the blower!

http://averagejoerestoration.com/resources/mustang-wiring-and-vacuum-diagrams/1964-mustang-wiring-diagrams/1964m.jpg

walt, those diagrams are available at www.averagejoerestoration.com

I ordered a few items and threw a resistor in so as soon as they get here I'll try that out thanks

MWM wrote:

Just a reminder, the blower motor may be safely removed at the firewall without messing with the heater box. Just a thought before you rewire

I guess you know a secret that I don't.  If it can please tell me how, I had this out right after I got this car and before I knew it was the wrong motor for the car.  It came out thru the dash after removing the heater box.  The way its put together I can not see how it can come out without the box removal..




 

Last edited by terry (2/14/2015 6:32 PM)

that would have been a great secret!  thanks though!!

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The motor has 2 wires . . one is ground which goes to the switch/resistor . . the other goes to 12 v that is only on when the key is on . . I think the brown one goes to power and the yellow is ground which goes to the common wire on your switch.

unplug your switch

Use your ohm meter to find which wire on the switch is common . . one wiring diagram says it is brown but I would check.

This wire will go to the ground wire on the switch.

One of the other wires will be used for high speed and the other for low speed.
 
Connect 1 of the switch wires to ground and check the fan speed . . it should be very fast . . the 66 did not use full power to the motor, it ised a resistor even on high speed . . if it is not too fast than it does not need a resistor and can be used for high speed . . if it is slow, your motor is old and you need a new one.
 
The other wire needs a resistor and will go from the resistor to ground . . the resistor will reduce the fan speed and it will get pretty warm.

set your volt meter on 20 amps and connect one end of it to ground and the other end to the ground wire on the motor and turn it on . . this will tell you how many amps it draws.

take this number and 13.5 volts and calculate what resistor you need to reduce it by 1/2 . . this will cut the fan speed to around 1/2 which can be word into the wire you use for low speed.
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Last edited by barnett468 (2/14/2015 11:42 PM)