Before you begin: Use your RV and component manuals for model-specific procedures. Stop and use a qualified professional for electrical, propane, structural, or other work beyond your training.
Why is my RV AC running but not cooling?
First confirm cooling mode, adequate power, closed openings, and unobstructed return and supply airflow. Clean the filter only as the unit manual directs. Breaker trips, repeated icing, or water near electrical parts call for service.
| Symptom | Safe check | Stop point |
|---|---|---|
| Fan runs, cabin stays warm | Thermostat mode, filter, blocked vents, open doors, and run time. | Service if airflow and settings are correct but cooling remains poor. |
| Indoor water | Is it tied to cooling or to rain? Note the exact location. | Turn off if water is near electrical parts; inspect drain, gasket, or roof opening professionally. |
| Breaker trips | Record when it happens; avoid repeated resets. | Qualified electrical diagnosis before reuse. |
Keep this record: Write down the AC model, thermostat setting, indoor/outdoor conditions, run time, filter condition, and any fault code.
First decide whether the unit runs
Confirm the thermostat is set to cooling and the chosen temperature is below room temperature. Check whether the fan runs and whether the unit starts and stays on. Record any error code from the thermostat or control panel.
If a breaker trips repeatedly, stop resetting it and arrange electrical service. Repeated trips can signal a fault that an owner should not bypass.
Check the easy airflow problems
Close open windows and roof vents, check that supply and return grilles are unobstructed, and inspect the return-air filter using the unit’s manual. A dirty filter can reduce airflow and cooling. Clean or replace it only by the approved method and reinstall it dry when required.
If airflow remains weak, the cause may be inside the blower, ducting, or coils. Leave internal electrical and moving-part work to a qualified technician.
Separate heat load from a malfunction
Direct sun, poor shade, frequent door opening, and high outdoor heat can make the space difficult to cool. Test under stable conditions and note outdoor and indoor temperatures, fan behavior, and how long the system ran. Do not infer a refrigerant fault from one brief test.
Use the model manual for any expected performance checks. A second rooftop unit or different thermostat zone may behave differently.
If water leaks indoors or ice appears
Switch the unit off if water approaches electrical components. Note whether the leak occurs only while cooling or after rain: condensation drainage, gasket problems, and roof water entry are different possibilities.
Ice and repeated freeze-up can be linked to airflow or another fault. Let the system thaw as the manual directs, then seek service if it recurs. Do not chip ice off the coils.
Know the service boundary
A technician can check supply voltage under load, capacitors, fan operation, refrigeration components, and the roof installation. Record model number, symptoms, and what you already checked. Avoid opening live electrical compartments or adding refrigerant without the equipment and training required.
Manufacturer manuals & further reading
Use these official resources to find details for your equipment. Match the brand, model, and revision; another RV’s procedure may not apply to yours.
- Dometic manuals and documentation
Look up operating instructions by product identification. Filters, cleaning methods, and service requirements vary across Dometic appliance models.
This guide is general educational information, not a substitute for your RV’s manuals or professional inspection.