Hydro Hot Problem

[Gil_Johnson]

I just discovered one of my Hydo Hot zones is not selectable on one thermostat.  The other works fine.  I did have the air conditioner replaced last year for this same zone.  Although it would be hard for me to believe, is there a furnace connection on the AC unit that might not have been connected?

Thanks,

[Gil_Johnson]

It looks like ther may be a dip switch setting for the furnace on the air conditioning unit, if I'm looking at the right one on line.  When it gets a bit warmer out I guess I need to climb on the roof and check that out.

[JimDyer]

If you have the Duo-therm 4 or 5 button thermostat, the actual control is in a board in your A/C unit. Connections use a 4 wire phone cable, and there needs to be a board for each zone. If you have three zones and two A/C's, there will be a third board hidden somewhere. Mine is over the table behind the Generator/Aquahot/water pump/Fill valve switches, but accessed by removing the vertical dividers inside the overhead cabinets.

If the A/C replacement was done by a tech inexperienced in better motorhomes, they may have connected the cable wrong. If you look online for the Duotherm thermostat manual,  it has a good description of the wiring and which wire goes where. IIRC one board is master and the wiring is different for masters and slaves. Access to the wiring is through the return plenum in your ceiling.

[Bill Sprague]

Gil,

I think you are on the right track.  A friend with a Monaco had some air conditioner work done and things didn't work right when he got the coach back.  When he took it back to the repair shop the very embarrassed technician declared "I forgot the dip switches!"  One was in the wrong spot.

[Jim Shaw]

Gil,
If you had a new A/C installed the tech may not have set the dip switch on the new A/C for your furnace to work. It happened to me last year. The dip switches are under the cover of the A/C.
Jim

[Gil_Johnson]

Great news, it was a simple dip switch setting on the AC unit's control panel.  So other than having to climb on the roof and accessing the panel, no big deal.  It is discouraging that CW didn't check their work when they replaced the unit last spring.

Thanks for your advice,