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View Full Version : HVAC Condensing Unit Wiring, Capacitors and Fan Motor


dmmx3
Jun 28, 2011, 12:30 PM
I have a split system AC unit, and the Fan motor (3 wires) on the outdoor unit stopped working a few days ago. It is about 90 degrees here so we noticed quickly. I checked out the unit, and realized the fan motor was hot to the touch (so hot that you couldn't hold it in your hand for more than a couple seconds), so I surmised the motor had gone bad, as it was still getting power. I picked up a new one (4 wires), and installed it.

The new motor came with a 2 prong capacitor. The old motor had a dual run (3 prong) capacitor. So I wired the new fan to the new capacitor, and kept the old capacitor in place for the wiring to the contactor and the condenser.

The new fan motor started right up, but I was not getting any cold air. I then bought a new 3 prong capacitor so that I could wire the fan motor and condenser/contactor to it, and capped the 4th wire (brown with white stripe). The fan would not start. So I rewired the fan to the 2 prong capacitor, and the contactor and condenser to the new 3 prong capacitor. The fan again worked, but still no cold air.

I have attached a diagram of how it is currently wired (no pun intended). I know very little of how this stuff works, other than what I have read on this forum.

If anyone could provide some insight it would be really appreciated. Thanks in advance.

twinkiedooter
Jun 28, 2011, 12:50 PM
Anyone who fools around with a high voltage appliance like a central air without any idea of what they are doing is really living dangerously. You can and will be fried by the high voltage if you do something wrong.

Bite the bullet and call in an a/c repairman before you do any permanent damage to the unit.

I realize you want to do this yourself and save some money, but if you do this wrong and wire it wrong, the whole shebang could end up shorting out your fuse box and/or have your house go up in flames.

Maybe the AC man on AMHD can shed some light onto your mess.

You should have replaced fan motor with the same model fan motor or one compatible with your unit. Sounds like you didn't get the right motor.

Also did you test each component to see if it was the relay switch gone bad and not the motor? Also if you are not getting any cold air there could be something else wrong with the unit and not just the fan such as low freon. Do you have the expensive freon testing equipment to properly test the unit out?

Just bite the bullet and call an a/c repair guy if you can get anyone out to your home during the hot weather.

Your fooling around with the unit will only get you bigger repair bills in the end. It's like trying to repair your car's engine with a pick axe or trying to staple jello to a tree. Both methods don't work so well.

The real problem could be inside the home and not outside at all. Ever dawn on you?

dmmx3
Jun 28, 2011, 01:05 PM
Anyone who fools around with a high voltage appliance like a central air without any idea of what they are doing is really living dangerously. You can and will be fried by the high voltage if you do something wrong.

Bite the bullet and call in an a/c repairman before you do any permanent damage to the unit.

I realize you want to do this yourself and save some money, but if you do this wrong and wire it wrong, the whole shebang could end up shorting out your fuse box and/or have your house go up in flames.

Maybe the AC man on AMHD can shed some light onto your mess.

You should have replaced fan motor with the same model fan motor or one compatible with your unit. Sounds like you didn't get the right motor.

Also did you test each component to see if it was the relay switch gone bad and not the motor? Also if you are not getting any cold air there could be something else wrong with the unit and not just the fan such as low freon. Do you have the expensive freon testing equipment to properly test the unit out?

Just bite the bullet and call an a/c repair guy if you can get anyone out to your home during the hot weather.

Your fooling around with the unit will only get you bigger repair bills in the end. It's like trying to repair your car's engine with a pick axe or trying to staple jello to a tree. Both methods don't work so well.

The real problem could be inside the home and not outside at all. Ever dawn on you?

I appreciate your concern. Thank you.

mygirlsdad77
Jun 28, 2011, 04:30 PM
Missing some wires there. Also, the way it is shown in the drawing, the fan motor would run constantly, as it is hooked to the incoming side of the contactor, not the outlet of the contactor. I agree with twink. Best bet is to hire a pro. Good luck and please let us know how things work out.