[bikestuff]

Here are pictures of the not burned terminal along with the nylon screws holding on the terminals that go to the compressors.

   
This is the still connected but loose 120V connector.  Note there is no nylon screw in the center of the terminal.

   
This is the underside of the same part of the board.

   
This is the underside of the compressor connectors that have the nylon screws connected.

[bikestuff]

Gurus,

Here is an update on the AC board issue.

I replaced the old board with one of Newell’s boards.  The installation was fairly straight forward with a couple of small issues.   I kept the external relays.

The board is held to a metal carrier by plastic hold-offs at the four corners.  In the central part of the board, the carrier had two hold offs that support the board in the middle.  Because of the way that the new board is made, some of the electrical components interfered with one of the central hold-offs.  I simply removed it.  There are no physical screws that support the board, only plastic hold offs.   (Maybe Newell should look into this)

I ran into another issue that was my fault.   The inside and outside fan motors plug onto the board with amphenol three pin connectors.  The original SCS board used a male connector on one and a female connector on the other to make sure you don’t plug into the wrong terminal.  The Newell board looked like it used identical connectors for both fans.   But (and its a big ole butt), they used different pins inside the connectors.  You will have to look closely to make sure you wire the right fan to the right connector.  Even when you recognize the issue, you have to pay attention or you might wire the fans two or three times before you get it right.  Ahem!  Don’t ask me how I know this.

One issue that I want to think about is the safety ground for the board.  The ground wire from the 120V circuit terminates on the carrier metal support…but the is NO GROUND at all on the control board since it is only supported by plastic standoffs.   I am not sure that this is an issue and the SCS board did not have a ground either…..but it seems to me that separating the Power and Neutral from the associated ground does not sound like a good idea.

One other bit of weirdness involved the J1 connector.   Two tiny gauge wires connect to the J1 connector.  Both the old board and the Newell board have a terminal (J1) for the wires.  When I unplugged the J1 connector, I realized that the old SCS board had both the pins broken off.   In other words the J1 connection was never functional.  Neither the installation manual nor the maintenance manual mention the purpose of the J1 connector but I believe it has something to do with the ability of the board to take a 120V input from the inverter.  In any case, I put a new connector on the two wires and plugged it into J1 terminal.   

After the new board was installed I fired up the AC unit and the current draws for the fans and compressors seemed reasonable. After a while I checked and was getting a delta temp of around 32 degrees!   It was 100f outside and AC was putting out 68f inside.  

One thing occurred to me regarding the AC units and if you have read this far, I think I will share it.  For a while now this AC unit would just cut off for a second and then start again.  I THOUGHT that this was related to a thermostat issue, but now I believe that this was the loose connector arcing.  Richard will tell you that shutting off and then immediately restarting a compressor is BAD!  It was doing that but never got to the top of the list.  So…if your AC unit stumbles and then “restarts” you should look to see if you have a power issue.

Thank you @"Richard"  and the other contributing gurus for helping me keep my senses about me while working to get the AC going again.

Cheers,
Bill

Ps.  I checked the control board for the rear unit and found that the center lugs of the 120V connects both had the nylon bolts as they should be.