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TowDawg · 12-09-2024, 08:02 PM

On my '02 Scepter, I've got a small electric heater in the "wet bay" where the water pump and holding tanks valves are. It's looks like a little one people would use in the office with an "on/off" switch and a dial thermostat.
Then on the inside "power panel", I've got a switch labeled "system heat" to turn it on from inside and a red light next to it that lights up when it's turned on.
I had it on for a little while last week and when I switched on the inside panel, the red light lit up and everything worked like it should. Then on Sat, I noticed the red light wasn't on anymore and the heater won't come on anymore.
I looked all in the bay where the heater is, and pulled the panel where the switch and light are, looking for an inline fuse, but there's not one. I also don't see any fuse in any of the fuse panels that say it's for it, nor do I see anything about it in the manual.
I haven't put a multimeter to the wiring at the switch, but does anyone know if there is a fuse for this system, or if the switch itself might have some kind of fuse in it and I just need to replace the entire switch?

jacwjames · 12-09-2024, 08:53 PM

Here is a wiring diagram for the system heat. When you open it the lines may be blurry, hit CTRL 5 and it will clear up.

On my 2002 Windsor in the rear passenger side electrical bay, left side, there is a copper bar with mini breakers attached to it. One of these is what supplies power to the wet bay heater.

There is a thermal fuse in the heater itself that will fail.

There is a small snap disc that in the wet bay that actually turns the heater on/off. This turns the heater on at ~38F and goes off ~45F

If your light came on whey you turned the switch on and it was fairly warm outside my guess is the snap disc has failed (or bypassed) and it allows the heater to run all the time. NOT GOOD.

Also attached is a parts breakdown of the system heat.

86scotty · 12-10-2024, 08:54 PM

Yep ^^^. This seems to be a guaranteed problem on these rigs for everyone eventually.

I tested my system heat light, after I learned what the system heat button was for (the first step that I don't think a lot of people ever get past). My light was good. Then I found my snap disk which is a treasure hunt for many owners as it was for me. eventually I found it and bypassed it and my heater came on.

So snap disk was my problem. I ordered one from Amazon, it got lost, ordered another and it also got lost (Weird coincidence as I haven't had a delivery get lost in years). But somehow they found it and it just arrived after being MIA for the last few weeks.

I figure by Spring I'll have the correct part. Perfect!

I'd bet on it being your snap disk. Very easy to bypass and check once you find it.

l1v3fr33ord1 · 12-11-2024, 05:57 AM

TowDawg-

Do the recommended tests first. If they show the heater has failed, the info below should help you.

Our coach's 3000RV wet bay heater failed. It's usually the thermal fuse that fails. I sent the heater to the manufacturer for repair. They sent me what appears to be an entirely new unit. Call "Connie H." at Family Safety Products (was Therm-Tech), (616) 530-6540, and see if they can do the same for you. The cost was under $100.

I had a thermal fuse to repair the heater, but a) could not figure out a non-destructive way of removing the old one from the heating element, and b) the wires in the heating element were breaking. So, I figured a factory repair was better than trying to replace the thermal fuse myself.

jacwjames · 12-11-2024, 08:24 AM

The snap disk has male connectors, the two wires that connect are female. I carry a male to male connector that I use to test the system heat by removing the two wires off the snap disk and using the male to male to test it.

In 2022 I took a Nov trip and it was cold. The system heat worked find but it got me thinking of having a back up plan in case the small heater failed. So I decided to installed heating pads under the fresh and gray/black tanks. The wiring schematic actually showed this as an option and I found a bundle of wires on top of the black tank and found they were for the heat pad option.

I bought two and installed under the fresh water tank, 75 watt each and both have an internal thermo switch. I also installed one under the gray/black tank startling each.

We just went through a cold spell of 16F, I tested the temps in my wet bay and they were 50F so all is working.

If my small heater goes out I can rely on the pad heaters