Not real sure what the year is on the furnace but, it is a Borg Warner York furnace.
The problem that I have is that I replaced the motor and without marking the wires
Before I disconnected them. I have four wires coming out of a junction box and they
Are all black. WHICH WIRES GO WHERE? Please help if you can.

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Originally Posted by Chad Atkinson

Not real sure what the year is on the furnace but, it is a Borg Warner York furnace.
The problem that I have is that I replaced the motor and without marking the wires
before I disconnected them. I have four wires coming out of a junction box and they
are all black. WHICH WIRES GO WHERE? Please help if you can.

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Is the electrical diagram present/legible? Are the wires stamped w/ numbers? (You might have to wipe them off to see) If old motor was 3-speed, you probably have 1 neutral & 3 speed tap leads. A volt/ohm meter would be really handy for determining which is neutral & which ones are for heating, cooling, & spare/unused.

Quote:

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Originally Posted by KC13

Is the electrical diagram present/legible? Are the wires stamped w/ numbers? (You might have to wipe them off to see) If old motor was 3-speed, you probably have 1 neutral & 3 speed tap leads. A volt/ohm meter would be really handy for determining which is neutral & which ones are for heating, cooling, & spare/unused.

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Yes, that old motor had four wires and so does the new one. The wires all had quick
Connects on them. I cut them off the old fan motor wires and spliced them back on
The new motor. The only problem that I have now is that I can't remember what wires
Went where! Is there a way of finding out where they go w/o a volt/ohm meter?

Yes, but it will be a bit more painstaking: you will have to physically trace each wire to its source. The neutral should, at some point, be connected directly to a neutral junction. Of the other three, one may not even be connected actively, and the other two represent the heating fan speed and the cooling fan speed. As long as you can be assured which one is the neutral and make the appropriate electrical connection to the motor, the others can be identified as follows: Turn off power supply to furnace & set t-stat fan selector switch to "on". Connect one of the 3 wires to motor, insulate the other 2 as well as the unused motor leads, & turn power on. Did the motor start? If not, turn power back off & repeat process for the other 2 until the motor starts: you have found the cooling speed wire. This one is usually connected to the high or medium speed motor lead. Set t-stat fan switch back to auto & turn power back off. Connect one of the remaining two furnace wires to one of the remaining two blower leads, turn power back on, & set t-stat to operate heating. Observe the furnace for the next few minutes. If blower starts after preheat period, you have found the heating speed wire. This one is usually connected to the medium or low speed motor lead. If blower did not start (you will notice that burners extinguished) then you have found the unused wire. Turn off power, make appropriate connections, turn power back on & set t-stat for desired operation.