Dometic DC-Kit
Official technical documentation and workshop diagnostics for Dometic DC-Kit.
Technical Specifications
Master Troubleshooting & Diagnostics Matrix
| Error Code / Indicator | Symptom / Meaning | Possible Cause | Step-by-Step DIY Fix | Suggested Actions |
|---|---|---|---|---|
N/A | Air conditioner does not operate in mobile mode or compressor shuts off while fan and inverter remain running | Light system voltage fell below switch-off value Ua due to high load, or consumer battery voltage dropped below inverter/charging current distributor threshold | Check alternator output, battery health, and verify switch-on/switch-off voltage settings (Ua / Ue) on the charging current distributor. | DIY Safe |
N/A | Inverter completely shuts off (no voltage at socket) | Consumer battery voltage dropped below Ubatt lower limit (10.5 V for 12V systems / 21 V for 24V systems) | Recharge batteries or start vehicle engine to raise on-board voltage to the inverter switch-on point, then manually restart the air conditioning unit. | DIY Safe |
N/A | Inverter switches off automatically due to low voltage | Supply battery voltage drops below the 21 V low-voltage protection threshold | Start the vehicle engine to allow the alternator to charge the batteries, or switch off heavy electrical consumers. | DIY Safe |
N/A | Roof air conditioner stops working while driving | Charging voltage regulator cut connection to supply battery due to low voltage, or battery voltage dropped below inverter switch-off point (21 V) | Check battery charge status, verify alternator D+ signal, and inspect fuse integrity. | DIY Safe |
Frequently Asked Questions
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.