by Barry and Cindy 1997 U270 36′
Because our coach has ducted air and a DuoTherm Comfort Control thermostat, we found we can make some ‘simple’ changes to optionally increase our cooling during hot weather and also to use our front roof A/C to cool our bedroom. For hot weather, we can now control both roof A/C units with the same front temperature sensor. If both front & rear are set to the same temperature, both turn on & off at the same time. If one unit is set to a higher temperature, we have two-stage cooling.
Having the ability to alternately use the bedroom temperature sensor to control the front A/C allows us to use the front A/C instead of the rear A/C in the following situations:
· Quieter operation because the cooling unit is further from the bedroom.
· Can still cool bedroom if rear A/C is not working.
· If the “bedroom” leg of campground electricity is not good (as we recently experienced), we can cool at night with the “front” leg.
Front A/C did not have its own temp sensor, so it always defaulted to the thermostat’s temp sensor. Rear A/C was wired to a temperature sensor (thermistor) mounted on a bedroom wall. Temperature sensors are optional if there is no sensor connected to the small white plug in the A/C wiring harness located above air filter, that A/C unit uses the temperature sensor located on the front of the Comfort Control thermostat.
All wiring changes were made with wall thermostat bottom switch turned off.
We ran a new 2-wire cable from rear A/C through the duct to front A/C and connected it to the unused front A/C temperature sensor wire, which if we connected to the bedroom temperature sensor, the front A/C would turn on & off based on bedroom temps.
The coach came with the bedroom temperature sensor connected to the rear A/C’s small white plug mentioned above. In the open space above the rear A/C air filter, I cut the bedroom temp sensor wire near the small white plug. We now have three open wires above the rear A/C air filter that we will connect to a new switch:
1. Front A/C new sensor wire
2. Rear A/C sensor wire
3. Bedroom temperature sensor wire.
We connected above three pairs of wires to a new DPDT center-off switch located near rear A/C. Wires do not seem to have any polarity, so either of the pairs can connect to the switch terminals.
· Center pair to bedroom wall temperature sensor wires.
· One end of the switch to rear A/C sensor wires.
· Another end switch to new front A/C sensor wires.
Switch Positions
NORMAL – Front A/C on the thermostat sensor. Rear A/C on bedroom sensor
HOT-DAY– Both Front & Rear A/C’s on the thermostat sensor.
ALT-NIGHT– Front A/C on bedroom sensor. Rear A/C on thermostat sensor and turned off
Switch toward the rear of coach we call NORMAL with front A/C on thermostat sensor & rear A/C connected to bedroom sensor.
Switch middle center-off we call HOT DAY with both rear & front A/C on thermostat’s sensor.
Switch toward front we call ALT BEDROOM with front A/C connected to bedroom temp sensor & rear A/C on thermostat sensor. In this case, we would turn off rear A/C.