[dreemail]

Tested it tonight . Both relays are connected and passing 120V to compressors. It feels colder inside but it was over a 100 most of today just East of Dallas. I will let it run tonight, and then button up the relay circuit box and mount it in place. Thank you for all your help. #NewellGurus are amazing. Please ping me with questions. The last diagram (compact version) is what I used. I did have to swap the A1 / A2 on one relay to make the connector trigger. That wire pair may have been reversed since that is the one that melted the plug —the reason for the relays —and is now just 2 wires soldered to the circuit board in place of the melted plug, and melted wires.

[Richard]

You probably did, but just to make sure. Comp 1 runs on one hour leg(black) and comp2 runs on the other (red) to keep the loads balanced. If you have four units, then reverse the legs for
The second unit to keep the loads balanced


Glad you are cool now!

[hbens]

I just completed this mod today. Thanks to Chester for the pictures and Richard for the dummy resistant theory of installation of the mod. I also made sure the upper and lower circuits on each side did not use the same hot leg so the loads will be more balanced.
I was able to source contactors locally for $22 each. MCG Industrial PN: MDP30A-2P-120
https://drive.google.com/file/d/1ICqJfXb...sp=sharing


These contactors have two circuits but I only used one side of the contactor. They also need a pretty tall enclosure vs. the short box I saw on Richard's coach. It is more expensive and water proof but the supply house had it on the shelf and I was able to mock up the inside of the box while in the store.
https://drive.google.com/file/d/1RQcZ0Xj...sp=sharing

The first side took me about 3 hours to complete. I took my time and checked things 3 times over before I snipped any wires.
The second time (1 week apart as I was awaiting parts) took me 2 hours to complete. Again I was working slow and methodical. The penalty for screwing up far exceeded the reward for finishing an hour early.

Thanks again to Chester, Richard and all those who added to this thread. Each entry was important to help me understand this.

[encantotom]

i have been meaning to do the relay mod on my coach for a long time.  i have had the relays for years.  

i had a knee replaced earlier this year and a few weeks ago injured a rib so i have been hobbling....but getting alot better.

richard and rhonda came and spent a week with us and richard and i caught up on most of the coach projects i have not been able to do myself this summer.  

this mod is one of them.  

something we added was led indicator lights for each compressor so you can look at the box and know if the compressor has power to it.

tom

[Dustun]

Tom, led lights are a very nice touch. Power check at a glance.

[Richard]

That was @"bikestuff" addition to the modification. It’s on my “list”to go back and add them.

[encantotom]

bill is a genius, so is richard

tom

[whited44]

This project is next on my list..

Couple questions
1. I have the small unit and large unit. Do I need a total of 3 relays to do everything?? Or does it take a relay for each compressor and one for each fan??
2. You guys have a link for those connectors that tie all the neutrals together??

My prob is when the thermostat calls for “cool” the compressors start but the fan doesn’t kick on.. so just the compressor runs until it would prob pop the breaker if I left it go. Am I barking up the right tree with this mod with these symptoms??

[[email protected]]

This project is next on my list.. 

Couple questions
1.  I have the small unit and large unit.  Do I need a total of 3 relays to do everything??  Or does it take a relay for each compressor and one for each fan??
2.  You guys have a link for those connectors that tie all the neutrals together??

My prob is when the thermostat calls for “cool” the compressors start but the fan doesn’t kick on..  so just the compressor runs until it would prob pop the breaker if I left it go.  Am I barking up the right tree with this mod with these symptoms??

I think the relay mod is only for the compressors, so if each unit has 2 compressors then you need 4 relays total. I do not think they are doing mods for the fan relays. 

I cannot remember the name of those connectors that Richard uses, we call them Polaris lugs in the electrical industry. 
Just found them, Alumiconn connectors:
https://www.homedepot.com/pep/AlumiConn-...lsrc=aw.ds

If your fan is not coming on, you may want to check and see if its the capacitor or it could be the fan motor itself. The cheat to check the fan is to just spin it and turn it on and see if it comes on. 

I know you may not want to do this right now but you may want to see what I did with mine. I ditched the old control boards all together and converted over to house thermostats. I love it, allows me to control the A/C's remotely from my phone over Wi-fi. 

Here is my thread on my mods:
https://newellgurus.com/showthread.php?tid=7503

[Richard]

If you have three compressors you need 3 relays.

The fan function was not changed only the compressor function.

If either fan fails to activate, the compressor will eventually overheat tripping the circuit breaker. Adding the external relays will do nothing to address this issue.

Let’s determine why the fan is not turning.
It could be a faulty capacitor for the fan.
It could be a failed circuit or connector on the circuit board.
It could be a failed fan motor.
It could be a faulty thermostat.

Is it the indoor or outdoor fan that is not working?
Do you have the SCS manual, excellent trouble shooting steps in the manual.
Are you comfortable working with live 120V?
Will your multimeter test capacitors?