My outside unit condenser fan motor would run fine, when pushed by a screwdriver, or the like, but would not start on it's own. I replaced the motor with the IDENTICAL unit, name brand and all, but the wires were different. I also replaced the capacitor. As it turns out, the capacitor they sold me was the wrong one for the compressor and motor together, but the right one for the motor by itself. But (I think) I have eliminated it as a bad unit, as I measured the voltage at the wires with the new and old units. The old fan had three wires, purple, black and brown. The new one came with black, brown, yellow and brown with a white stripe. Both motors have diagrams on the side, and I got the hot(yellow) and common(black) wires hooked up fine to the 240, but if I pick one of the other two to hook up to the capacitor, it wont start at all. I spliced both wires together, and the fan ran for about long enough for me to button up the housing and it thermal protected and stopped.=me mad: The motor was definitely hot to touch. The motor is an A.O.Smith, 1/6 hp, .9 amp 208~230 volt motor. Virtually identical to the old one...except the wires and colors, and the new motor spins at 1075, and the old one at 840 rpm. The outdoor condenser is a Janitrol, made by goodman mfg. inc., and our thermostat is a programmable honeywell unit. I am USUALLY quite competent at this sort of thing. But I am at a complete loss for what to do next. PLEASE HELP!!!!

both the brown and the brown/white strip should go the the new contactor one to each side ,,one on one post the other on other post,,,,,,,should work providing you havn`t burned up the new motor
the rpm`s should have been the same as the old motor although 840 rpm sounds a little slow,,,,,but its ok better to be running faster than to slow,,someone could have replaced the original with a motor that runs to slow for most the 1075 rpm is the right speed
let us know

some goodmans run at 875 rpms....

Thank you all for your much appreciated help. Turns out, the four wire motor needed it's own capacitor. I simply left the compressor on the original capacitor, and usewd the new one for the fan motor. I also had the yellow wire going to the wrong power source. OMG! I feel so dumb now that I understand!!