[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 !!!!