Sound like 12V DC is OK as it is swapping to propane when in auto and NO 120V AC detected.
SO...........
120V AC at outlet in outside compartment where power cord plugs in?
YES......
Then you need to remove cover on control module. Unplug power cord from module, unplug DC leads from module. Remove the cover screws and any clips (can be 1,2,3 Screws)
5A glass fuse is for AC ....check heater element. (44 ohms)
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31