Lost Zone 1

[Chris362]

I did a search, but I didn't find anything to help me out.
Here's my problem:

On my Duo Therm Comfort Control panel, 5 buttons, I have Zones 1 and 2.

Zone 1 - Front A/C - Heat Pump - Fan - Furnace
Zone 2 - Back A/C - Heat Pump - Fan

I took the RV out of storage and fired it up.
I noticed that zone 1 was lacking the different options (blank screen - but the backlight was on). When I turned the power on and off or unplugged the data cable, the missing options would briefly appear but it was still missing the Furnace. I couldn't do anything with what briefly appeared anyway.
Zone 2 was working correctly.

I reset the thermostat and got a code of FF. But, now Zone 1 was completely missing, not even an option in the modes.
Zone 2 still showed and worked correctly.

I've tried cleaning the data cables on the front and rear A/Cs and cleaning the Comfort Control panel with contact cleaner, but no happiness.

Before I take it in, I thought I would see if anyone had any ideas about anything else I could check or a way I can diagnose to see to what may be bad.

2003 National Dolphin

Thanks.

 

[hirsttool]

I have the same problem. Did you ever solve the furnace problem?

 

[Henry J Fate]

Probably either a bad board in the  control panel or bad data cable.

A helpful test would be to change the data cables at the control board. I think the connectors at the control board for stage 1 and 2 are the same. If you can switch the indentity of the units by changing the cables it may offer  helpful information.

Another thought would be to disconnect all power to the control board. You can usually do that by removing all the connectors for a few minutes. Many times boards will respond to a power reset. You can do the same at the stage/unit locations by disconnecting the 12 volt control power.