Owners of recreational vehicles (RVs) rely on dependable climate control systems to make their travels comfortable in changing weather conditions. Dometic is one of the most popular brands of RV thermostats, but these devices can develop issues over time that prevent you from easily regulating temperatures inside your camper or motorhome.
In this comprehensive guide, learn about the most common Dometic RV thermostat problems owners encounter and actionable tips to get your unit working properly again.
Symptoms of a Faulty Dometic Thermostat
Before delving into specific problems and fixes, understanding the signs of thermostat failure will help you identify issues promptly. Be on the lookout for these common indicators:
- Inconsistent temperatures that are too hot or cold no matter the thermostat setting
- Thermostat doesn’t power on even with new batteries
- Fan continues running even without a call for cooling
- No power to the thermostat backlighting
- Display errors like E1, E2, etc.
- Strange clicking sounds from the thermostat
- Failures to automatically switch between AC and furnace
If you notice any of those issues, it likely means the thermostat needs troubleshooting attention and potentially replacement parts to work correctly again.
Why Dometic RV Thermostats Stop Working
Dometic RV thermostats are subjected to a lot of vibrations from travel which can loosen connections and lead to lost power over time. Battery corrosion is also a common culprit when an older thermostat no longer turns on. Issues can also arise from:
- Damage from improper winterization allowing water leaks
- Short circuits from electrical surges
- Normal wear after 5+ years of use
Keeping batteries fresh, avoiding extreme hot/cold exposure, and handling the device gently will maximize lifespan. But even well-maintained units eventually need repairs.
Top 5 Dometic Thermostat Problems and Solutions
Here are five of the most widely reported Dometic RV thermostat issues owners face along with tips to get each problem fixed:
Problem #1: Thermostat Lacks Power
If your Dometic thermostat suddenly stops turning on even after replacing the batteries, there could be a few explanations:
- Test voltage connections for damage
- Check fuses/breakers
- Replace control board if faulty
- Test wall-mount transformer that steps down 120V AC to 12V DC
Problem #2: Fan Runs Constantly
A stuck fan that never stops running can be caused by wiring problems or circuit board damage telling it to stay on indefinitely.
- Inspect relays and fans for debris
- Test wiring for short circuit
- Replace control board if faulty
- Reset thermostat to defaults
Problem #3: Temperature Reading is Inaccurate
Frustratingly, Dometic thermostats sometimes fail to accurately measure ambient temperature leading to uncomfortable interior temps.
- Check thermistor wires are intact
- Ensure sensors are clean
- Adjust offsets if reading is slightly off
- Replace control board if necessary
Problem #4: AC Unit Doesn’t Switch On
If the thermostat won’t automatically turn on the AC when temperatures rise, that points to an issue with the relay.
- Test relay circuit connections
- Replace damaged relay
- Check for obstructions on circuit board
- Replace control board if damaged
Problem #5: Display Error Codes
Seeing odd error codes like E1, E2, etc means the auto-diagnostics detected an internal problem.
- Lookup code meanings in manual
- Reset device to defaults
- Replace batteries/power
- Repair damaged components
- Replace control board if faulty
By matching the specific error on your display to the diagnostics manual, you can get closer to pinpointing the failed parts.
How to Reset a Dometic Thermostat
If your Dometic thermostat problems persist even after troubleshooting:
- Switch unit off
- Remove batteries
- Hold down blank square button
- Reinstall batteries while still pressing button for 10+ seconds
- Configure desired settings
Resetting everything to factory conditions will often solve firmware glitches exhibiting strange behaviors.
When to Replace a Faulty Dometic RV Thermostat
While Dometic thermostats can last 5-10 years if properly maintained, they do eventually wear out. If you’ve diagnosed connections, tested parts only to find that issues keep occurring: replacement is the prudent option.
Installing a brand new thermostat will provide the latest features and reliability your RV needs to handle temperature control for years to come.
How Much Does Replacing a Dometic RV Thermostat Cost?
Plan to budget $100-300+ to replace a faulty Dometic thermostat:
-$100-150 for a new Dometic Duo-Therm analog unit -$150-250 for a premium Dometic digital thermostat with humidity and WiFi features -$100+ for labor if installing yourself seems too complex
Upgrading to a modern digital model allows controlling temperatures via phone apps while traveling. Avoid entry-level generic thermostats that won’t integrate properly and might lack critical safety features.
FAQs about Troubleshooting Dometic RV Thermostats
RV owners asked these common questions have when dealing with Dometic thermostat failure:
How do I determine the correct replacement Dometic thermostat?
Choosing the right model requires matching:
- Power input (12V DC)
- Number of heating zones
- Dimension fit
- Wiring terminals
- Display type (digital vs analog)
- Required safety certifications
Consult manuals, sales receipts, or Dometic customer service to pick the best equivalent option.
Why does my Dometic thermostat turn on the AC and furnace simultaneously?
Simultaneously switching between AC/heat happens when the reversing valve is damaged causing refrigerant pressure issues that confuse the system. This problem requires repair by an HVAC technician as simply changing the thermostat won’t fix the underlying issue.
Why does the AC run with very cold air in heating mode?
If the AC activates during heat mode delivering cold air, that indicates a damaged reversing valve that has failed to redirect refrigerant properly based on the thermostat setting. You’ll need an expert to replace the valve and potentially recharge the refrigerant.
The thermostat replacement process sounds intimidating – is it really difficult?
While attempting a DIY install requires working with intricate wiring, the basic process of swapping a new Dometic for old isn’t necessarily as hard as it seems. Referencing wire diagrams, labeling connections, and moving one wire/clip at a time prevents critical mistakes. Seek help if unsure.
Malfunctioning Dometic thermostats that lead to uncomfortable hot or cold conditions can ruin the RV living experience. By learning the common failure points, troubleshooting wiring and parts methodically, and resetting/replacing components, you can regain climate control.
Pay attention as issues develop, safety test all repairs, and don’t hesitate to phone Dometic support lines or RV technician pros when the problem complexity exceeds your confidence level. Investing a little time and money into thermostat maintenance goes a long way towards reliability.