I went to Wal-Mart yesterday to get a non-programmable thermostat. I ended up buying a Honeywell programmable one because it was cheaper than an older non-programmable model on the shelf! This is the model I purchased: Honeywell 5-2 Day Programmable Thermostat - Walmart.com
For $19 plus $3 for a SPST mini toggle switch from Radio Shack, I had a superior thermostat and the toggle switch allowed me to retain the low/high fan a/c option.
Next mod is to install a 3 volt (actually 3.3 volt) voltage regulator so I can completely eliminate the 2 AA batteries and use 12 V battery power.
I normally would build my own voltage regulator but you can't beat the $3.49 cent price of this item: 12V to 3 3V DC DC Buck Converter Power Supply Voltage Regulator WD | eBay
That is about what it would cost me in gas to drive to the nearest radio shack for parts not to mention time involved soldering.
I used the wiring instructions for my Duotherm on the following website: https://sites.google.com/site/jdbeas...statconversion
I did not solder to any back terminals for the high fan option--not necessary. All you need is to put both the low fan and high fan wire into the same "G" terminal (both wires fit easily) with the high fan (blue wire) switched on/off with an aftermarket toggle or slide switch. I did have to solder two wires onto the toggle switch and that was very easy to do.
The thermostat I used didn't have much room for a toggle switch. I cut back some of the plastic inside the thermostat to make room for the toggle switch. I cut a piece of plastic off the thermostat packing to use as an insulator because the toggle switch was touching the circuit board-things were tight but everything worked!
Level of difficulty on a scale of 1 to 5 is a 2...only because the thermostat wires in the RV are very fragile and came apart inside the heat shrink tape when I soldered them to jumper wires.....be very gentle..the thin solid copper wire can snap easily.