If you have a dual light switch AC power set up in your coach this simple power mod will allow you to run both AC units while on shore power at most RV parks.
This is the type you should have for this mod.
Here are the materials needed, short piece of romex, a two pole motor-switch, a cut in box, a 50' 12 ga extension cord,
First you must identify what wires go where and label them.
I did this buy running power to the coach and flipping the switches and testing for power
Once I isolated the one that goes directly to the rear AC I disconnected it from the switch.
I then used a box knife to cut the hole for the new switch box, It's easy the wood is thin.
Next I wired the existing wire to the AC to the center position of the two pole switch (on/off/on)
then I ran a jumper from the old switch to one of the poles on the new switch, I the cut the female end off of my 12 ga 50' extension cord and wired it to the last pole on the new switch. (first I drilled a hole up into the coach feeding the extension cord in)
The I cleaned it all up and put it all together.
WaLa, now I can run both AC units via the 30 amp and 20 power out lets that most parks provide. Simply flip the new switch to AUX. (down for me)
there is no flow thru so there is no power coming out of the male end, Also while the switch is in the coach position (up for me the way I wired it) the other two switch work as normal.
The ground fault or 20 amp breaker on the pole protects the unit.
If I missed any details let me know.