Well gang... I gone and done it. I got the Honeywell thermostat installed and all figured out. The first thing to suggest is to open up the access to both the furnace and the A/C unit and look at the wiring layout. Now I know with RV system there is no exact code they must hold to for color or labeling. So once I look at the furnace I saw a Red and White wire. So back at the thermostat I unhooked and touch them together and presto heater. Now also looking at the old thermostat the Red from the furnace was labeled +12V. Which it was a power lead so knowing this I place that lead to the R terminal on the new thermostat. The White wen to the W terminal. Now the A/C part was pretty easy. When I got the cover off I noticed right away the terminals where labeled already. But there is a catch the G is not just G its GL (lo fan - White) and GH (hi fan Green). So I used the GH lead in the G terminal of the thermostat the other GL lead I just taped up the end. The Y lead went to the Y terminal of the thermostat. Now there is a Blue wire (from the A/C) tied to Ground. Which I left and not used on the Honeywell thermostat but it was used on the Coleman for circuit ground. But after turning on the DC and AC power again and testing. Wow! I got a good thermostat! No more waking up at night either freezing or frying from lack of heat or a runaway heater. As for that problem I did find that problem and could fix it. It a cracked solder joint on the circuit board so as you slide the temp slider up or down it either hooked up or didn't. But why fix it when I got better now! Oh a better understanding of the terminal codes... http://wiki.xtronics.com/index.php/Thermostat_signals_and_wiring

I replaced mine a couple of years ago. Man, WHAT A DIFFERENCE!! Mine went from a 10* temp swing to holding about 2*. The only thing I ran into was I lost the medium speed on the blower switch. I had to connect the medium and high speed wires together to get the blower to run.

I'm going to gain back my fan speed switch on my A/C after I pick up a SPDT switch then I can select either lo or hi then. I've got GL and GH so I just got to select either GH or GL to be hooked to the G terminal.

Neat! Plus, if you don't sit on level ground (if the old one was the mercury switch type) you will still maintain equal temperature.

I like it. I dont however enjoy the 10* temp swings as MnTom mentioned.

The old one was a electronic thermostat. But it also had the 10 degree swings so set it at 75*F and it would swing low to 70*F kick in the furnace run all the way to 80*F till your sweating to death then shut off and then slowly sink to 70*F till your feeling cold again.

The old one was a electronic thermostat. But it also had the 10 degree swings so set it at 75*F and it would swing low to 70*F kick in the furnace run all the way to 80*F till your sweating to death then shut off and then slowly sink to 70*F till your feeling cold again.

I even complained about that when my trailer was under warranty. I was told that the swing was NORMAL! I argued since I have done HVAC/R that was abnormal but they would not do anything.