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So #490 has a list, as all things seem to. The couple of high priority items are tires, steering issues and air conditioning issues, then aqua hot/water heater issues.

So I pulled one of the basement airs out, it’s an SCS dual stage package unit. Found out they are sealed systems with no service ports and you have to pull the entire unit out to service it. Not very service friendly. Pulling the unit was not too difficult, luckily they they are located in a bay and are fairly easy to get to. So I found a burned up control board, and after some research I decided I am going to ditch the entire board and re-wire everything with some relays and a 24vac transformer so I can use a house style thermostat with Wi-Fi capability.

New shoes delivered:
   
Burned up board
   
Disconnecting the duct work to get the unit out:
   
New relays and transformer installed:
   
Unit almost ready to go back in, notice I made some cut outs in the top to get to the new service ports that are going to be added:
   

[Richard]

Jeff,

This will depend upon the signals coming out of the new thermostat that you use but the original thermostat has a quirk in that the condenser motor will get both a low speed and high speed signal once the second compressor kicks in. That is because the condenser motor gets it’s power from the same relay as the compressor. It looks like you have used four relays meaning you have the same situation. I don’t think you want the low speed and high speed windings of the compressor motor powered at the same time.

The solution is to add one more relay. If it has both NO and NC terminals then run the power for the low speed throw the NC terminals. Trigger the relay with the signal for the second compressor. That way when the 2nd compressor fires the low speed circuit for the fan motor is interuppted. There are other ways, but that is the way I have done it.

I know you are electrically savvy, but if you want a schematic, give a shout, and I will cobble one up

Nice creative solution !!!!

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Jeff,

This will depend upon the signals coming out of the new thermostat that you use but the original thermostat has a quirk in that the condenser motor will get both a low speed and high speed signal once the second compressor kicks in. That is because the condenser motor gets it’s power from the same relay as the compressor. It looks like you have used four relays meaning you have the same situation. I don’t think you want the low speed and high speed windings of the compressor motor powered at the same time.

The solution is to add one more relay. If it has both NO and NC terminals then run the power for the low speed throw the NC terminals. Trigger the relay with the signal for the second compressor. That way when the 2nd compressor fires the low speed circuit for the fan motor is interuppted. There are other ways, but that is the way I have done it.

I know you are electrically savvy, but if you want a schematic, give a shout, and I will cobble one up

Nice creative solution !!!!

Yes that is exactly my plan, those relays have no and nc contacts. The power to the condenser fan relay will be derived from the load side of the compressor number one relay, this will help eliminate a relay. I am actually adding two more larger relays for the compressors as the relays pictured are only rated for 12 amps, so they are going to trigger larger relays to switch the compressors on. I will post a wiring schematic once I get it finalized and that will make things easier to see. I have a rough layout but I am still fine tuning to capture most of the original functions. 
The indoor blower motor may only run on high speed but I am still working that out.

[Richard]

I wouldn’t worry about the indoor blower. I can barely tell the difference between hi and lo on the indoor. Outdoor is a different story.

[Jack Houpe]

Nice job Jeff! I hope to meet you someday, love your videos.

[BusNit]

Love creative solutions. Much like the Wanderlodge group, we have to engineer, fabricate and think outside the box with these.

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I wouldn’t worry about the indoor blower. I can barely tell the difference between hi and lo on the indoor. Outdoor is a different story.

Thanks Richard, that is kinda what I was thinking, did not seem to be much difference in high and low for the indoor blower. I will stick with high for now. The outdoor will switch to high anytime it calls for the second compressor.

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Nice job Jeff! I hope to meet you someday, love your videos.

Thanks Jack, hopefully we will cross paths some day. 
I am going to try to organize a get together at the Florida Flywheelers park in Feb 2024, it’s dry camping but you can run your generator as much as you like.

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Love creative solutions. Much like the Wanderlodge group, we have to engineer, fabricate and think outside the box with these.

Yes, I have learned to adapt many things for both work and for the Wanderlodge too. It comes in handy when you run into obstacles.

[Latitude 28]

Jeff,
Nice job and great solution! I still have my original boards both have been rebuilt once. As a result of that experience I did the relay mod that Richard came up with and got the high current off the board. Looks like the next time around I'll go your route....thanks for posting!

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Jeff,
Nice job and great solution!  I still have my original boards both have been rebuilt once.  As a result of that experience I did the relay mod that Richard came up with and got the high current off the board.  Looks like the next time around I'll go your route....thanks for posting!

Thanks and no problem. I will hopefully have a video of the work on my YouTube channel at some point. I am very behind on videos and editing, lots of other things to do.

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So here is the wiring diagram for the new relays:

230-08-11 NEWELL SCS AIR DIAGRAM-F.pdf Size: 1.88 MB  Downloads: 34

You could simplify things by replacing the two relays for the compressors with 24v coil relays instead of 120v. I had the 120v coil relays already so that is why I am using them.