You may have seen this on the Tinkerer Thread?
AES - tricking it to only use propane -
I disconnected the red 12vdc (wire nut big and small wire together that was on the heater + lug) from the heater element AND unplugged the AC power cord.
That forces AES to go directly to propane. I've read the AES can get flakey so this insures I am running 100% propane for testing.
Good way to troubleshoot AES too, by forcing in a mode.