AC Issue....
Verify you have 120VAC At the outlet power cord plugs into
Grey Case Module
Verify you have 120VAC between J5 (Hot) and J6 (neutral) terminals
Verify you have 120VAC on both sides of the 5A AC Fuse
Controls in AUTO
Verify you have 120VAC between J7 and J8 AC Heater Element leads
Flip Cover Module
Verify you have 120VAC between P1 (Hot) and P2 (neutral) terminals
Verify you have 120VAC on both sides of the 5A Glass AC fuse
Controls in AUTO
Then should have 120VAC between P3 and P4 AC Heater Element leads
Service Manual
https://bryantrv.com/docs2/docs/Serv...&%20RM3962.pdf
As for conversion to 12VDC HVAC unit.........DOES JC even have one for that 3862 Model???