Thermostat Upgrade
The Mountaineer came from the factory with a Duo-therm Vented A/C and a Suburban Central Heating System.  Both systems are very effective and keep the Mountaineer comfortable in summer's heat and winter's cold.  The only issue I had with the system was with the Duo-Therm thermostat that came with the system.  It was a mechanical (analog) thermostat which resulted in difficulty setting the desired temperature (no digital display)  and a wide variance in temperature on and off settings. I decided to correct this by installing a Hunter Digital Thermostat Model 42995B available at Walmart for $20.00. 
Step 1
Shut off 120 volt AC and 12 volt DC sources to the AC, Heater and thermostat.  (Remember the 12 volt  coach battery supplies power even when the 120 volt AC  is disconnected.)
Step 2
Remove old thermostat and note wire colors and connections.  Follow directions included with the new thermostat for removal of old thermostat.
Step 3
Connect orange and blue wires to the connector marked "G".  (Connecting both wires to "G" will result in your A/C fan running at high speed.  You may add a SPST Switch between the blue wire and the G connector to allow high or low speed fan.)
Connect the white wire to the "W" connector.  Connect the yellow wire to the "Y" connector.  Connect the black wire to the "Rh" and "Rc" connectors using the jumper included with the thermostat.  Leave the red wire disconnected as it is not used in this application.
Step 4
Secure thermostat base to wall using the included screws and snap the thermostat face into position as instructed in installation instructions.
Step 5
Install 2 AA batteries (These must be installed for A/C and Heat to work - make sure you keep spares in coach.)
Step 6
Restore AC and DC power to the coach.
Step 7
Set thermostat and enjoy
Disclaimer:  If you are uncomfortable working with electricity use an electrician or HVAC professional for installation.

Links to related sites for installation of digital thermostats in RVs.:
Coleman A/C, RV Thermostat
Hosted by www.Geocities.ws

1