Furnace issue could not believe the fix.

[GreG L.]

Coming back from CA in August the furnace went out.
The symptoms:
Starts, heats up then shuts down after 15 to 20 seconds.
Noticed that if I restart it right away it shuts down faster unless than if I let it sit. When it does shut down the relay on the circuit board chatters for a minute or so then starts up again only to shutdown. The light on the circuit board indicated an air flow issue.
Trouble shooting:
Checked the fuse, then the sail switch, ohm 'ed it, took it out and pressed it manually, not the issue. Changed the circuit board and it had the same issue.
Called a mobile tech:
He went through the same steps I did, even changed the thermistor because it was obvious something was heating up and causing the shutdown because of how quick it would shut sown the second time unless you let it rest. He even called Dometic twice and found that the 12 volts was dropping to 6 when it shut down until the relay quit chattering.
The Solution:
After two hours with the tech. he happened to come around to the door side after trying it a couple of times and said a few choice words, a fuse light was on, before I could get there to look it was out, the 15 amp furnace fuse. He change the fuse and it worked. Looking closer at the fuse it was different than all the others, thicker, black and you couldn't see through it so I broke the top off and there was a resistor instead of a fusible link. The only thing we could think was that the resistor was opening up and them closing once current was removed.
Now the question, does anyone know where to get one?