Coleman Electric Furnace No Heat Troubleshoot 3400 series.
I found most temperature and no heat problems are caused by bad sequencers, Your no heat situation could vary from sequencers to limit switches to the heat elements them selves. If you get sporadic heat or no blower in auto mode the replace the sequencers.
The elect furnaces that are used in mobile homes are very strait forward and from about 1984 to present are basically the same design. REMEMBER TURN OFF POWER before taking the unit apart!!!

NOTE 1132022........
Try... https://colemanhvacparts.com/collecti...
AND
https://amzn.to/3zJ0PF3
The Amazon link is generic as there are 3 different sequencers, use the coleman parts page to find your exact replacement part.