BradW wrote:
In our 2019 Lance Truck Camper we have a Dometic GC6AA Gas/Electric water heater. It works fine most of the time but occasionally it will not work on gas or electric. Its an intermittent problem that happened 5 or 6 times back in the summer over a 3 week trip.
The problem is we turn it on inside the camper and nothing happens. It doesn't work on gas or electric. I have been able to get it working by unplugging the two long flat plugs which plug into the module and then plugging them back in.
I suspect one of the terminals is not getting a good connection, but they are are perfectly clean and look brand new.
Any ideas?
Thanks, bradW
Hi, what you are reporting I have seen often with corrosion, even on 1-year-old units.
See this pic, it is an older unit, but you should have the same thermal fuse.
It appears you have tried the PC board connections, (and they can be bad too) but another location I have found is more problematic than the PC board connections.
Look at the brown wire with the red angled connector that plugs into the T Stat. Also at the T stat, is a semi-clear tube, and in the tube looks like a resistor of sorts, but is not a resistor. It is a thermal fuse, a safety device. If a fire breaks out in the outside compartment, it will melt and shut down the system.
They crimp on spade male and female ends on the leads of the thermal fuse. The T stat end has a female end on it and plugs into the T stat. The other end of the thermal fuse has a male end and plugs into the red-angle female connector. The red wire connector end seems to get corroded more than in other locations. It may just be exposed to more moisture, but it is my first go-to place when the PC board plug and unplug does not fix the issue.
If that thermal fuse does not make contact, nothing in the heater, gas or electric, will work. With the system on gas mode, and needing to heat the water, sometimes, you wiggle that thermal fuse connection, and the heater will take off. Be ready for the burner to light when it makes. Then you know that is the problem to clean up.
A quick way to test if the system is working is to flip on the heater gas mode; if you do not hear a "clunk" from the gas valve followed by click click click of the igniter, soon, then you know something is not made, most likely in the safety circuit or the PC board connection. If you are on electric-only mode, you hear nothing and only know it is working 20 - 30 minutes later when there is no hot water.
Hope this helps,
John
PS, Getting the thermal fuse to unplug from the connections can be a bugger. The female ends have a tang inside that grips the male spade hard. Make sure you hold onto the wire connection and wiggle it as you pull. Don't just yank on the clean tube in the middle; odds are you will break the thermal fuse. I use needle nose pliers on the tube ends close to the connection to hold it; it helps.
