[a-dub]

i don't think that's true. i still have a thinkeco ac modlet that coned sent me years ago as part of some kind of "make your ac smart" promotion.

if you turn those knobs to the off position while the compressor is running, does it actually go into some kind of orderly shutdown or does it abruptly cut power to the compressor?

[bob1029]

The wiring diagram for this article seems to reflect it would be a hard shutdown. Most HVAC systems I have interacted with have zero problems with a sudden power loss. The only potential issue is bringing the compressor back up too quickly on the other side. You could easily control for this if you were switching the whole unit using software.

[inigyou]

I don't think its the shutdown that's the problem but the restart. If I fiddle with the thermostat on my fridge, it turns off in one direction, but if I turn it all the opposite way it won't come back on for a few minutes. I think this is the relevant interlock. Something about letting pressure equalize.

[EvanAnderson]

High head pressure on startup is the problem I'm thinking of. Generally there is a delay after shutdown and a lockout on restart until the head pressure is lower. In the old refrigeration compressors I am familiar with there was an electromechanical timer to facilitate this lockout.