Frost formation on evaporator coil / extremely cold air output at very low air speed

Possible cause: Dirty filter, obstructed vents, low outdoor temperatures, or improper airflow. Check and clean filter if dirty. Ensure vents are open and unobstructed. Adjust thermostat to a warmer setting or switch to FAN ONLY mode until coil is clear of frost.

Frequent tripping of fuses or circuit breakers / lack of cooling

Possible cause: Improperly installed or sealed division plate leading to premature freeze control cycle activation. Verify division plate is firmly sealed against the bottom of the unit base and double-sided tape on ceiling template, ensuring cold discharge air does not leak into the return air opening.

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Dometic • Air Conditioner

Dometic Rooftop Air Conditioner

Official technical documentation and workshop diagnostics for Dometic Rooftop Air Conditioner.

Technical Specifications

Electrical120 VCA, 60 Hz, 1-phase. Model 541915A70X: Compressor FLA 12.0 A, LRA 58.0 A, Fan FLA 3.0 A, LRA 8.5 A. Model 541916A70X: Compressor FLA 13.2 A, LRA 60.0 A, Fan FLA 2.8 A, LRA 7.6 A. Circuit protection: 20 A time-delay fuse or circuit breaker. Minimum copper wire gauge: 12 AWG up to 7.3 m (24 ft). Low voltage supply: 12 VCC (18-22 AWG). Generator size: 3.5 kW (1 app.) / 5.0 kW (2 app.).

Gas Or PressureRefrigerant R-410A - 547 mL (18.5 oz) for 541915A70X; 872 mL (29.5 oz) for 541916A70X. Duct static pressure (high speed fan, filter and grille in place): 1.4 - 2.79 cm (0.55 - 1.10 in) for 541915 series; 1.78 - 2.79 cm (0.50 - 1.10 in) for 541916 series.

Capacities DimensionsNominal cooling capacity: 3,957 W/h (13,500 BTU/h) for 541915A70X; 4,397 W/h (15,000 BTU/h) for 541916A70X. Roof opening: 36.2 ± 0.32 cm (14-1/4 ± 1/8 in) square. Roof cavity depth: 5.1 cm (2 in) min to 14 cm (5-1/2 in) max. Minimum return air free area: 258 cm² (40 in²). Duct length: 4.6 m (15 ft) min to 12.2 m (40 ft) max.

Master Troubleshooting & Diagnostics Matrix

Error Code / Indicator	Symptom / Meaning	Step-by-Step DIY Fix	Suggested Actions
`N/A`	Frost formation on evaporator coil / extremely cold air output at very low air speed Possible Cause: Dirty filter, obstructed vents, low outdoor temperatures, or improper airflow	Check and clean filter if dirty. Ensure vents are open and unobstructed. Adjust thermostat to a warmer setting or switch to FAN ONLY mode until coil is clear of frost.	DIY Safe
`N/A`	Frequent tripping of fuses or circuit breakers / lack of cooling Possible Cause: Improperly installed or sealed division plate leading to premature freeze control cycle activation	Verify division plate is firmly sealed against the bottom of the unit base and double-sided tape on ceiling template, ensuring cold discharge air does not leak into the return air opening.	DIY Safe

Frequently Asked Questions

Q: MY ROOFTOP UNIT HAS THE ELECTRIC HEAT STRIP OPTION (NON-HEAT PUMP ELECTRIC HEAT OPTION), BUT WHEN IT GETS COLDER OUTSIDE IT DOESN’T SEEM TO MAINTAIN THE TEMPERATURE. WHAT SHOULD I DO?

Electric heat strips are designed to take the chill out of the air inside your motorhome, but they are not intended to be the primary heat source for cold weather camping. When outdoor temperatures drop significantly, the heat loss of the motorhome typically exceeds the capacity of a standard electric heat strip.

Q: WHAT ARE THE BENEFITS OF A MOTORHOME AIR CONDITIONER?

An motorhome air conditioner helps maintain a comfortable indoor climate, reduces humidity levels inside the vehicle, and filters out dust and pollen, creating a more pleasant and healthy living space while traveling or camping.

Q: WHAT IS THE IDEAL AIR CONDITIONING TEMPERATURE?

The ideal indoor air conditioning temperature for an motorhome is generally between 70°F and 72°F (21°C to 22°C), balancing comfort and energy efficiency.

Q: WHAT MOTORHOME AC DO I NEED IN WARM LOCATIONS?

For extremely warm locations or larger motorhomes, a high-capacity rooftop air conditioner (such as a 13,500 BTU or 15,000 BTU unit) or a dual AC setup is recommended to adequately cool the space.

Q: HOW DOES MOTORHOME AIR CONDITIONING WORK?

Motorhome air conditioning works on the same principle as a standard home AC unit. It uses a refrigeration cycle involving a compressor, condenser, expansion valve, and evaporator to absorb heat from the interior air and exhaust it outside, while blowing cooled air back into the motorhome.

Q: HOW TO RUN MY MOTORHOME AC WITH A GENERATOR?

To run your motorhome air conditioner with a generator, ensure the generator has sufficient running and starting wattage (surge wattage) to handle the compressor's startup load—typically a minimum of 2,000 to 3,000 watts depending on the AC unit size. Always start the generator and let it stabilize before turning on the air conditioner.

Q: HOW TO RUN MY MOTORHOME AIR CONDITIONER ON THE CAMPSITE?

To run your motorhome air conditioner at a campsite, connect your motorhome to an appropriate power pedestal (usually 30-amp or 50-amp service) matching your motorhomes electrical system requirements. Ensure other high-draw appliances are managed to avoid tripping the campsite breaker.