Quote:
Originally Posted by Craigcounty
Thanks again for the input, I solved it at 10pm est last night. It was the 15A black fuse! I swapped it with a standard 15A and it fired up and stayed running. The black 15A is supposedly re-setable, must be weak. Kinda feel like a dumba** for not snapping to it earlier.
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It's the black resettable fuse!
As an electronics, mechanically inclined engineer. I spent 2 days, emptying my storage, taking down the wall, bleeding propane, removing the heater multiple times, testing the sail switch NO. (Normally open)
Testing the limit switch NC (Normally closed)
At wits end, I was ready to start ordering expensive parts when my wife found your post.
The boys at Keystone actually caused a new problem trying to solve a different one.
Evidently, the Dometic DFMD35121 pulls very close to the 12 v. 15 amp limit.
So surge current could possibly blow a quick blow fuse. (If this occurs on yours, try a slo-blow fuse) So Keystone adds a BLACK resettable fuse that increases resistance (lowering current). This is actually a poor application of the fuse in a 12 volt system because it drops more voltage.
Here's EXACTLY what is happening:
1. 12v blower turns on drawing current.
2. BLACK fuse heats up adding resistance to the blower circuit.
3. Black fuse drops voltage reducing voltage to the blower motor.
4. 12 v blower slows down.
5. Either (due to low air flow) tripping the sail switch or more likely overheating entire system and triggering the limit switch, the circuit board shuts down the system.
6. Error flashes 1 blink every 3 seconds indicating low air flow.
Replace the 15 amp BLACK fuse with a 15 amp quick blow fuse.