Dometic Blizzard NXT
Official technical documentation and workshop diagnostics for Blizzard NXT.
Technical Specifications
Master Troubleshooting & Diagnostics Matrix
| Error Code / Indicator | Symptom / Meaning | Possible Cause | Step-by-Step DIY Fix | Suggested Actions |
|---|---|---|---|---|
N/A | Unit does not operate | Generator not running or producing power, land line power supply improperly sized or unplugged, or fuse/circuit breaker open or tripped | Verify generator operation, verify land line power connection and sizing, and check/reset fuses or circuit breakers | DIY Safe |
N/A | Frost formation on cooling coil / evaporator icing | Dirty air filter, obstructed air vents, low outside ambient temperatures, or restricted airflow | Inspect and clean dirty air filter, ensure air vents are open and unobstructed, adjust thermostat to a warmer setting counter-clockwise, or run on FAN ONLY setting until frost clears | DIY Safe |
N/A | Coils freezing or improper cooling performance | Inadequate airflow or restricted distribution vents | Ensure a minimum of 2 distribution vents (or the quick cool vent and 1 vent) remain fully open during cool mode operation; check for blocked filters or return air restrictions. | DIY Safe |
N/A | AC power connector failure or loose wires in strain relief housing | Wires extended past insulation stops or connector re-used after closing | Re-terminate wiring using a NEW connector if wires extend past insulation stops or if the housing has been previously closed. | DIY Safe |
N/A | CCC 2 thermostat does not recognize updated dip switch selections | System reset was not performed after changing dip switch settings | Ensure thermostat is in OFF mode, simultaneously press MODE and ZONE buttons until LCD displays 'IniT' and all available zones, release buttons, and press ON/OFF to exit. | DIY Safe |
N/A | Water's getting into the motorhomes living space through the ducting and/or return-air grille | Could be high static pressure, restricted airflow, a poor install, unsealed mounting holes, missing foam blocks over the drain holes, collapsed ducting, or unsealed plumbing/wire penetrations | On pre-2016 units, seal any unused mounting holes with silicone (post-2016 units come pre-sealed); confirm the lag screws holding it down are sealed and the foam roof-gasket blocks sit under the mounting holes; fit foam cover blocks over the drain holes (kit no. 3316781.000); inspect and repair or replace any collapsed ducting; secure the control box wiring so it doesn't restrict airflow; seal every hole around plumbing tubes and wires with sealing putty; wrap ducts with sealant tape; and clear any debris from the condensation drain holes. | DIY Safe |
N/A | Features do not work after installation (Fan, Cooling, Heating, Furnace) | Incorrect wiring, improper communication cable termination, or incorrect dip switch configuration. | Turn off the power at both the mains and the 12V side, then go over every wiring connection, check the RJ-11-6C4P pinouts and that the right dip switches are ON, and reset the system. | DIY Safe |
N/A | Rapid compressor cycling, reduced performance, or power supply overload. | Improperly installed or missing divider in the return air cavity allowing cold discharged air to leak into the return air stream. | Ensure the divider is firmly pushed against the base and sealed with double-sided tape and foam insulation without blocking the product data plate. | DIY Safe |
Frequently Asked Questions
Q: My rooftop air conditioner has the optional electric heat strip, but it can't keep the vehicle warm when it's colder outside - what should I do?
The heat strip isn't designed to replace the vehicle's main heating in cold weather - it's only meant to take the chill off on cool days or mornings. To use it: turn the selector to the 'OPT HEAT' position, and the heat strip will switch on and start warming; once the vehicle reaches the temperature you want, turn the selector to 'OFF' or 'FAN'. The thermostat does not switch the fan/heater on and off by itself.
Q: Why fit air conditioning to a motorhome or caravan?
Comfort depends on humidity as well as temperature. We can tolerate up to about 26°C (78°F) only when the air is dry; in humid air, around 20°C (68°F) is the comfortable limit. Most people feel best at roughly 18-22°C (64-72°F) with 40-70% relative humidity. Achieving that in a motorhome means cooling the air and drying it at the same time, which needs a compressor air conditioner - systems relying on direct or indirect evaporative cooling are less effective.
Q: What temperature should I set the air conditioning to?
How warm the air feels can differ from what the thermometer says, and humidity makes a big difference. In dry heat, sweat evaporates quickly from the skin and cools us, so we cope with high temperatures; in humid heat, sweat evaporates less, so we feel hotter, and the damp, sticky air can affect circulation and sleep. That's why a good air conditioner needs to lower the humidity as well as the temperature. Dometic suggests around 26°C (78°F) is usually comfortable.
Q: How powerful an air conditioner do I need for hot countries?
If you mostly tour in cooler climates, the air conditioner won't be pushed hard and a lower-rated unit will be enough. If you regularly travel somewhere hot - especially with children or pets on board - don't skimp on output, as a motorhome or caravan can quickly get uncomfortable on a hot day, and when nights stay warm too, you'll only rest properly with an adequately sized unit.
Q: How does motorhome air conditioning work?
Much like a household fridge, but far more powerful: a refrigerant draws heat out of the space being cooled and releases it outside - and in a motorhome or caravan it should also reduce the humidity. Evaporative systems are a common alternative: a roof-mounted unit evaporates water into a filter, and a fan pulls outside air through it so heat is exchanged.
They use little power and are light, but their effectiveness depends on the outside humidity, so performance varies - it falls away above 85% humidity, exactly when cooling is most needed - and they always add humidity inside the vehicle, whatever the conditions. Caravans and motorhomes don't have thick walls like a house, so even well-insulated ones heat up in the sun, easily reaching 30°C or more inside - in temperate climates as well as hot ones.
How hot it gets also depends on window size and number (small windows heat up more slowly than large glazed areas), on whether you're parked in sun or shade, and on whether you air the vehicle out or keep everything shut.
Q: Can I run my air conditioner from a generator?
Yes - a generator gives you a reliable power supply wherever there's no mains hook-up, so you can keep your home comforts when touring off the beaten track. Dometic makes generators for exactly this.
Q: Can I run my air conditioner on a campsite hook-up?
Usually, yes. An air conditioner draws more current at start-up than any other appliance you're likely to have on board, but only for a fraction of a second - it uses far less once it's running. Most campsite hook-ups are protected by a time-delay fuse, so those brief peaks don't normally cause a problem.