That thermal fuse on stack....overheating sensor that trips if coolant flow is obstructed causing the coolant to overheat.
If Norcold it trips at 700*F
If Dometic it trips at 375*F ?
Check for any signs of a leak
Ammonia smell, yellowish residue around burner area, lack of cooling etc
Is it time for YOUR Medication or Mine?
Dodge 3500 w/Tractor Motor & NUWA 5vr
US NAVY---USS Decatur DDG-31