Hi there. I just bought a new AC fan motor for an old Trane AC. New Fan motor for inside unit has more wires than the original fan motor. Here's the info:

AC Unit:
1986 Trane
Has 3 connection wires:
White
Red
Off-White
**Connection site is has wires in a plastic plug format

Old Fan Motor: wires are in plastic plug format to fit into AC unit
White and Red wires are for speed
2 brown wires for Capacitor
Off-white - common wire?

New Fan Motor: 1/3 HP, 115 Volts, 1075 Rotation, 3 speed, reversible
Wires: wires are loose... not in plug format - I assume I need to splice
Green ground wire - connected to fan motor assembly
2 brown wires for Capacitor, bought Capacitor rated for new motor so we're good here
Black- high speed
Blue- med speed
Red - low speed
Yellow wire -? Common wire?

So... the AC unit seems to have 2 connection wires and a common wire. Which wires in the new fan motor correspond to the connection wires in the AC unit?


Thanks in advance for any help offered!! We're low on cash and trying to conserve money by fixing ourselves.

You will have to determine which wires are for heat and which is for cool. Heat usually uses the low speed (RED) and cooling usually uses the (BLUE) or (BLACK) depending upon the requirements of your system.

As far as the yellow wire goes I have no real idea since that is not a standard motor color code for 115 volt use.

The motor you have will tell you exactly hoe to wire it. The label is on the side of the motor or on a paper in the box. Follow those directions.

Example below.

Are you sure there's not a white wire? Most new multi speed motors have black(high speed), blue(medium high speed), yellow(medium low speed), red(low speed) and white(common), two browns(to capacitor), and of course a green (ground). I agree with HVAC1000. Between the instructions that came with the new motor and the wiring diagram on the furnace, you should be able to get it all figured out. Good luck. Lee.

You will have to determine which wires are for heat and which is for cool. Heat usually uses the low speed (RED) and cooling usually uses the (BLUE) or (BLACK) depending upon the requirements of your system.

As far as the yellow wire goes I have no real idea since that is not a standard motor color code for 115 volt use.

The motor you have will tell you exactly hoe to wire it. The label is on the side of the motor or on a paper in the box. Follow those directions.

Example below.

Well the real question is which of the wires (Red, Black, Blue, Yellow) from new motor gets connected to the red, and white, and off-white wires on the AC unit? I'm assuming the one of these is the common wire.

NO white wires on the new motor. Just the ones listed above.

Any ideas? Thanks again!!

As mentioned before look at the diagram on the side of the motor.

If that no name no model number motor was made in China all bets are off. The China motors are JUNK.

Most people who post here will provide a brand and model number so we can use our resources and look it up.

As mentioned before look at the diagram on the side of the motor.

If that no name no model number motor was made in China all bets are off. The China motors are JUNK.

Most people who post here will provide a brand and model number so we can use our resources and look it up.

Motor is an A.O. Smith: 1/3 HP, 1075 RPM, 115 Volts. Trying to get the model number for you. Hope to have it later today for you.

Thanks again!