wa8yxm
I think your answer is definitely on the right track. R.V. Electrical control mechanisms used to be utterly analog mechanical. Not. Any. More.
I used to challenge doubters to do their own test. Keep touching the starter motor contact the power contact as the motor chugs over the engine to start then the key is released when the engine stats.
ZOT
SUR-
JOLT
PRISE!
I had to suppress a mobile office A/C unit, because shutoff signal was jolting the unit off-line. Total shutdown not merely compressor cutout.
LITTLEFUSE 5KP is my favorite for this kind of work Bi-Directional. 5KP190CA to be specific. It responds in 5 one billionths of a second. Earth ground must be viable for this suppressor to work. I use them in parallels of (5) units. But I also clamp line to neutral. Then neutral to earth.
I have such a system integrated with my Sola ferroresonant line tamer. But on a recloser circuit. Three times and you're out. A mechanical outage.
Such behavior as the OP's delinquent interaction between the A/C and Switches and selector is preventable.
