Please help, my outdoor unit quit working. I think it was a lightening strike. A wire which crossed above the contactor's coil's blade (I'm calling the thing you slide the wires onto blades) melted and arced on the blade. The wire was connected to a capacitor. I replaced the contactor, wire, and capacitor. The contactor won't pull down. It is getting 24 volts from the thermostat via the blower unit's circuit board and that circuit is being completed back to the board. The brown wire brings the current and the yellow wire returns it before going through the high pressure sensor and reset button. I bypassed these items in the circuit and still had the same problem. The unit will work if I manually push down on the contactor. The contactor will pull down if I run a wire from the contactor's coil's blade and ground it on the outside unit. So I figure the contactor must supposed to get its ground through the circuit board. There is only one fuse on the board, a purple 3, and it has been replaced. The blower and the thermostat work in conjunction with the furnace the way it should. The blower works consistently when the thermostat is set to cool and the room temperature is higher than the thermostat's setting. The only thing I can figure is that the circuit board is supposed to ground the capacitor via the yellow wire somehow and maybe some little transistor or something on the board is fried. There is no evidence of damage to the board so I am stumped. I hate to buy a new board only to find out that this doesn't solve my problem. Does anybody have any ideas on this one? Thank you. Sincerely, Kent Siems

There are only two low voltage wires entering the outside unit yea? If so, check for 24v between the two wires where they hook to the transformer. Let me know what you find and I will try to help.
Im guessing you have a bad wire between the condenser(outside unit) and the furnace/ airhandler. Can you post a pic of your outside unit contactor, and one of the furnace control board? Normally, there are two low voltage wires between the outside and inside units. One will hook to Y(with a wire from the y on the thermostat) and one will hook to c in the inside unit. Then, they just run out and hook to the coil of the trans.

Thank you for your reply.
There are two low voltage wires going from the circuit board and out to the coil on the contactor. One is hot with 24 volts when the thermostat is set on cool and the temperature is set to cooler than the room temperature. The second one is hot with 24 volts when they are both on the coil with the same conditions listed above. The voltage also returns to the ciruit board in the air handler.
The contactor will pull down when I have the return low voltage wire disconnected and I ground the exit end of the coil to the outside unit. I don't know if the circuit board is supposed to ground the contactor somehow and that feature is blown or if there is some type of safety device that is preventing the contactor to not pull down when it receives the 24 volts on the entry side of its coil.
The wire going to the circuit board on the air handler from the thermostat has several wires coming into the circuit board and they are all screwed on to posts on the board along with the two low voltage wires going to the outside unit. There is also a set of wires that go to a humidifier which is attached to the air ducting in which water trickles over a metal mesh and the air blows over the mesh to add moisture to the air in the winter when the furnace is running. I don't think the issue is there but I thought I best include that information just in case it is relevant. I'll try to get some photos on here later in the day.
Thank you.

The transformer should not be grounded. Sounds like 1 side shorted and broke. Check the 2 contactor coils wires for voltage, check the color of these wires and physically follow the wires, hopefully it is all in conduit, and check for the 24 volts at the board where the 2 contactor wires are, disconnect if possible and check for 24 volts between the 2.
Then verify neither of the 2 controls wires is grounded, and then be sure both are intact. Reconnect, now if you have 24 volts at board, you should have 24 volts to coil with no connection to ground.

I would not touch the yet.
Easiest test would be a working board?

I misspoke on my first post when I said "The only thing I can figure is that the circuit board is supposed to ground the capacitor via the yellow wire somehow and maybe some little transistor or something on the board is fried." I meant to say "ground the CONTACTOR" not ground the CAPACITOR. Since this was just my speculation I don't think it will effect anybody's answer. Sorry for this misspoke and thanks to all for responding. I'll try some of the suggestions and get back to this post later. -Kent

I took it you meant ground 1 side of the contactor coil, Then I said,

"The transformer should not be grounded. Sounds like 1 side shorted and broke. check the 2 contactor coils wires for voltage, check the color of these wires and physically follow the wires, hopefully it is all in conduit, and check for the 24 volts at the the board where the 2 contactor wires are, disconnect if possible and check for 24 volts between the 2.
then verify neither of the 2 controls wires is grounded, and then be sure both are intact. Reconnect, now if you have 24 volts at board, you should have 24 volts to coil with no connection to ground."
Have you read and/or done this yet?

Stratmando, Thanks for all of your replies. I hadn't read this post when I responded to your answer on my other post. I apologize. More details will follow.

On my board I have a red wire on a metal post labeled "C" and a white wire on a metal post labeled "Y" , both going to the outside unit's contactor coil.

Coming from the thermostat is a red wire on the post labeled "R", a white wire on the post labeled "W" a green wire on a post labeled "G" and a yellow wire sharing the post labeled "Y" with the white wire from the outside unit mentioned above. There is a post labeled "Twin" which is not being used and there is a blue wire from the thermostat which is not being used.

I should mention I have a humidifier that is wired from the board to a transformer and then to a humdity control switch to control water flow over a metal mesh with which the heated air passes through in the winter time. I don't believe this effects any of my current issues.

I have tested the red and white whire and the both have 24 volts at the board. I believe the white wire is sending and the red wire is the return of the circuit.

The white wire is spliced into a brown wire in the outside unit and then connected directly to the left side of the coil. The red wire is spliced into a yellow wire which is on the opposite side of the brown wire on the coil. It goes from the coil, to a high pressure sensor, then to a reset button, and then that is when it is spliced into the red wire which returns to the board in the blower unit.

I spliced the reset button and the high pressure sensor out of the circuit at one time to see if that would fix the problem but it did not.

I'll be submitting some photos shortly.

If you go to my Facebook page following the below link you should be able to see the photos I took along with some comments I made on them. Thank you.
Kent's HVAC Troubles | Facebook

Which are the 2 wires that go to the Outdoor compressor Unit on that circuit board.

Okay, looks like maybe a rheem, ruud, or possibly weatherking condenser? Anyway, you say you have tested both the red and white wires and get 24v at both. That seems off.

Now, what I really need to know, is what reading do you get when you put one lead of your tester on the red, the other lead on the white? I need to know if there is 24v between red and white when there is a call for cooling (check this on the control board first, between c and y, should read 24v. No testing to ground here okay? just between c and y when stat is calling for cooling. Let me know what you find.

You are saying both have voltages at the board. You need to check voltage between the 2, not ground,(sounds like you are using ground as a reference)? But since you have found a possible control wire to ground problem, it now needs to be checked out. Earlier post is helpful if followed.

Since you are going through a couple of senders/sensors, you should test voltage in and out of each.
No matter what,
IF 24 VOLTS IS AT THE contactor coil, it should energize unless it is bad, wrong voltage or froze, I am not thinking Troll?

Stratmando, Your 1st question at 06:17 PM: in my Facebook photo (Facebook) you'll see a brown sleeve with two wires coming out. One is white and it is connected to the terminal screw labeled "Y". The other is red and it is connected to the terminal screw labeled "C". The terminals from left to right are C-R-W-G-Y-TWIN. There is a strand of fiberglass like material which is dangeling from the brown sleeve that almost looks like a wire, but it is not. When Red and White reach the outside unit Red gets spliced into Yellow and white gets spliced into brown. Yellow and Brown then pop up through a small hole in the box containing the contactor, a relay, and two capacitors. Brown enters the contactor's coil's left side and yellow goes through a pressure sensor and a reset button before connecting to the right side of the contactor's coil. I hope this helps clear things up a little. Thank you for your response. - Kent

If you have voltage between the c and y. you likely have a low volyage control wiring problem.
Need to verify neither is touching ground and both have continuity. Good Luck.

Today I took the contactor to the air handler unit and connected it directly to the board via the C and Y terminals with some standard 12 ga home wires. The contactor did not pull down. Then I tested both wires with my voltmeter and got somewhere around 24+ volts on the Y wire and nothing on the C wire. I looked at the transformer and followed its wires to the board. One was Com and the other I don't remember. I figured the com was common just like the C on the top of the board where the red wire from outside connected. When I ran a wire from com to the contactor (instead of from C) and the Y wire ran to the other side of the contactor, it worked! Yippee. So I figured my "C" terminal must be dead. This time I completely removed the board (last time I just peaked behind it) and I noticed that the etched circuit from Com to C was melted apart. I'm having a friend run a wire between the two to fix the connection and I am hoping that it will fix my problem and that I didn't fry it while troubleshooting. I should get my board back tomorrow and hopefully will have things up and running. I'll keep my progress posted. Thanks again for everybody who has been helping me. The more I get into this the more I understand it and as I reread your answers I can understand what you wrote much better now. I can see why I can be frustrating to communicate with. It's like a bulb just came on and now things make a whole lot more sense than they did before. - Kent

On transformers you check for voltage between the 2 wires, not ground and each wire.
You do want the conductors off ground.
This is why I am saying 1 wire must be grounded if you are getting 24 volts on 1, and none on the other, and you are measuring off ground.
Disconnect the 2 wires in the air handler that go out to compressor contactor. Bring contactor in and connect directly at air handler with short pieces of wire. You don't need to hook and supply wires, just the control wires.
If it works there:
Check continuity between the conductors and verify NO CONNECTION TO GROUND, on the wires that go outside.
Please answer. Are the control wires in conduit? did you follow to see any physical damage or pinched?