waste tank heater

[Blue~Go]

Astro: No fuse.... how interesting.

Either you've gotten lucky and they didn't bother to double-check they'd replaced it after working on the Air-con. Or there is some other problem so it was removed. If I had to guess I'd say the former (hope so).

As far as using the 4-button control, I'm no expert but what I think there would have to be is some sort of control or junction thingie up in (or by) the Air-conditioner itself. Reason I say that is I saw all of these connections when I removed mine. Essentially, there was a "phone cord" type wire that went from up under the AC shroud over (through the roof) and down to the furnace. I think the phone cord to the furnace probably needs the junction up in the AC area.

That said, I would have to wonder if there wouldn't be any number of thermostats you could buy today that would work as well or better to control the furnace (separately) (granted, not "original").

if you do dig into it, I may have some photos from when I removed things and/or the manual.

Joan: Glad you got your furnace issue solved. Those blade fuses can be quite tight to take in and out. If/when you figure out the tank heaters it will be interesting to know what it was.

[chin_k]

I would just unplug another 20A fuse that I don't care for (VCP?) and stick it in the empty slot just to see if the tank heater light will come on with the switch, and if the furnace start working again. I am impatient that way when it comes to troubleshooting.