DUO THERM THERMOSTAT ISSUE

[camperjim]

Have a 2007 Crossroads Zinger. It has the attached thermostat, but branded "duo therm". It does not control the temp on auto. It only starts heat OR cooling if you put it all the way to 90 degrees on AUTO, or if I just use it on "ON". I am assuming I need to replace it, but just wanted to double check here for any "stupid" thing I may be overlooking. The ONLY thing I could come up with is I do not have a battery because my camper is permanently parked.

Any ideas?

 

[Kirk]

The auto function is only for the fan, as the label says. In the auto position the blower of the air conditioner will turn off when the compressor cycles off but in the on position it will operate all of the time. The HI/LO switch is also for the air conditioner and just changes the fan speed. The System switch selects if you use the air conditioner, the furnace or have both turned off. It sounds like it is working as intended.

 

[camperjim]

The auto function is only for the fan, as the label says. In the auto position the blower of the air conditioner will turn off when the compressor cycles off but in the on position it will operate all of the time. The HI/LO switch is also for the air conditioner and just changes the fan speed. The System switch selects if you use the air conditioner, the furnace or have both turned off. It sounds like it is working as intended.

I have read all that, but the temperature is NOT adjusting. The AC will keep take it down below 60 degrees in there no matter where I set it and the heat will go to 100 degress not matter where it's set.

Neither will start unless you set the temp all the way up to 90 degrees.

 

[Isaac-1]

I had one like this fail with wide temperature swings I replaced it with a residential Honeywell brand thermostat, there are a number of places online with instructions on how to do this modification

 

[OldWEB]

It could be possible that it does not like the fact there is no battery. The system(s) run off of the 12VDC and the converter may supply "dirty" power to it which may affect its operation.
Unless your 12V is fed from some pure DC supply, I would try installing a battery... just borrow one from the next door ATV.... ;-)

 

[Isaac-1]

I agree, any 12V lead acid battery will do, even one of those $30 lawn mower batteries, as all you need it for is to buffer out the dirty power from the 12V converter. (not all converters are designed to work without a battery in the system) 12V is needed for the control boards on the refrigerator, water heater and air conditioner

 

[Kirk]

It does not control the temp on auto.

Neither will start unless you set the temp all the way up to 90 degrees.

I based my response on the first quote.