Air Conditioner: Roof AC Tips

The recommended operating voltage for the roof air conditioner is 120 Volts AC (minimum is 108 Volts AC – maximum is 132 Volts AC). Low voltage is a factor in how the air conditioner operates. When the shore power supply is limited, other appliances in the vehicle are competing with the air conditioner system for amperage, or the power supply at a campground has maxed out, then it may be necessary to run the generator for maximum air conditioner efficiency. If the roof air conditioner fails to operate, check the breaker located in the front breaker panel. The battery cut off switch must also be on for the roof air conditioner to operate.

Get a head start on hot outdoor temperatures by using the air conditioner system to cool the interior early in the day, closing window shades to reduce glare and keeping trips in and out the entry door to a minimum. During drive time it is recommended to operate the generator when power is required to run the roof air conditioner.

During high humidity, weather set the air conditioning system to High instead of Auto. This will help to move more air over the coils and reduce moisture build-up. Slightly open a window or ceiling vent to help cycle the air.

Inside the ceiling, the mount is a removable filter that must be washed every two weeks while the motor home is in use. Operating the roof air conditioner with a clogged filter reduces the flow of air across the cooling coils and can cause the system to freeze up. Wash the filter in warm water and mild detergent. Rinse thoroughly and then allow the filter to completely dry before reinstalling. Do not operate the air conditioner system without the air filter in place.

The roof air conditioners are installed using a foam base gasket. Mounting bolts are used to secure this gasket and can be found beneath the inside roof mount. In some model units, the mounting bolts are located under the roof mount and behind a metal faceplate. Depending on the model type, there may be two or four bolts. Road vibration can cause the mounting bolts to loosen over time. Twice annually torque the mounting bolts and compress the gasket to one-half inch.

Ceiling vents are designed to move air through the vehicle and can be removed to access the air conditioner ducts where dust and debris, including pet hair, will collect. Twice each year remove the vents and wipe out the ducts using a cloth attached to a stick with electrical tape. A Comfort Control thermostat mounted on the wall controls the roof air conditioner. The wall thermostat requires 12 Volts DC to operate. Turn the on/off switch to on and press the zone button until the system cycles to the ‘Cool’ mode. Use the Up and Down buttons to set the desired temperature. If your Comfort Control is equipped with a Fan setting, press the button to choose a speed. In Auto Fan mode the system will self-regulate the fan. Avoid directly spraying cleaning agents on the Comfort Control; instead, use a soft damp cloth to wipe the box. 12 Volts DC operates the Comfort Control box. If the thermostat fails to operate, check the fuse, which is generally located on the interior fuse panel.

Regularly inspect the roof shroud for bird nests or other debris that may restrict proper ventilation. Road vibration can cause the shroud to loosen. The four mounting screws located at the roof shroud should be tightened snugly at least twice each year.