I have a York AC unit where the circuit board is shot, so I bought a replacement circuit board (same model). The model number for the board is 031-00251C.

Pictures of old circuit board: http://imgur.com/gallery/0efD1/new

I'm considering replacing this myself, but have no experience. Any tips? Yes, I'll make sure the power is off first. Is there anything I should know ahead of time or how I should get started?

  • There's a DIY or home improvement SE site isn't there? This might be more on-topic there. – Brian Drummond Jun 26 '14 at 17:25
  • @BrianDrummond Ok, I'll migrate this. Let's see how it goes. – Nick Alexeev Jun 26 '14 at 17:59
  • Have you checked the relay that is to the right in the first picture? They tend to develop some stickiness that prevents them from operating properly. With the power off, just press the center of it a few times to get it unstuck. – Brad Gilbert Jun 27 '14 at 12:24

First, be wary of the two big capacitors. One is the large "beer-can"-shaped component against the inside wall of the enclosure, and the other is the smaller, silver oval-shaped can right next to it. These can hold electrical charge, and could hurt you. You'll want make sure that they're discharged.

Once you unplug the unit, wait a few minutes for the caps to discharge on their own. Then, get a piece of insulated wire, or pliers with insulated handles, and short out the two terminals on the top of the cap. It may make a good spark, which is why you're doing it! Better to spark through the wire than through you :)

There's a third cap on the pcb (big silver unit with a wire coming out either end), you should probably discharge this one, too.

The white connector up top will be easy. Generally you just grab all the cables together and pull it out. There may be a latching mechanism holding things together that's not visible in the photo.

At the bottom of PCB (going by picture orientation), look at the black and brown wires that are connected to the board. The are using "quick disconnects", which can get to be fairly tight. Grab the connector (not the wire), and rock it back and forth (the long way) as you pull on it. Needle-nosed pliers might help.

Those wires have wire nuts on them too, but I would leave them alone. Once you are finished, give each wire coming from the wire nuts a firm tug, to make sure they haven't loosened up.

Oh, and I recommend marking the wires before you disconnect them. You can make small tags on the wires using masking tape.

Should be pretty straight-forward. Good luck!


It looks like all the wires have connectors on them, so nothing crazy like soldering will be required. Compare the old board and the new board to make sure that all of the connections have the same labels, and label all the wires accordingly.

Just make sure the power to everything is turned off and go for it.


Use masking tape to label the conditioner's connections to the board made w red/blue wirenuts before you take them apart. A simple 1 to 4 -> left to right will keep you from swapping around by accident. It wouldn't hurt to mark one of the plugin connectors with a sharpy either.

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