RV Air Conditioner Runs but Does Not Cool

Establish what is operating

Set the thermostat to cooling and lower than room temperature. After the built-in delay, listen for the deeper compressor sound in addition to the fan. Record any displayed code and whether the compressor starts, stops quickly, or never starts.

Give the unit enough time to stabilize, then compare return-air and supply-air temperature with appropriate instruments if you know how to do so safely. A brief hand check at a vent is not a diagnosis.

Restore basic airflow

Turn the system off before removing washable return-air filters. Clean and dry them as directed by the manufacturer. Confirm supply registers are open and the return path is not blocked by luggage, bedding, or a closed divider.

• Look for visible ice at accessible indoor openings.
• Allow ice to thaw naturally; do not apply heat or chip it.
• Check that rooftop airflow is not covered by debris from ground level.
• Close doors and windows while evaluating performance.

Consider the power source

Low campground voltage and overloaded circuits can prevent reliable compressor operation. Turn off other high-draw appliances and use an approved RV voltage monitor. Do not open a pedestal or breaker panel.

A breaker that trips again after one reset indicates a fault or overload that must be investigated rather than repeatedly reset.

Codes and service boundaries

Dometic FreshJet codes distinguish sensor, communication, current-sensing, compressor, and inverter-module faults. A normal power cycle and clean airflow may be reasonable owner steps, but bypassing a sensor or probing rooftop electronics is not.