Safety first: Turn off 120-volt power before opening an air-conditioner control box or handling sensor wiring. A reset can confirm a temporary connection problem, but bypassing a freeze or temperature sensor removes protection and can damage the equipment.

Dometic Comfort Control Center 2 error codes describe the circuit the thermostat cannot read and the modes it locks out. That makes the code more useful than the symptom alone. An E5 that stops air conditioning needs a different path from an E4 that may leave cooling available but disable heat-pump operation.

First note the code and blinking zone number. Multi-zone systems can have one healthy zone and one faulted zone, and a reset can erase the evidence a technician needs.

Read the code and zone together

The CCC2 displays the error where the temperature setpoint normally appears. A blinking zone number identifies the affected zone. Cycle through zones and write down every code before changing power or configuration.

Do not use an error-code chart from a different Dometic thermostat. Capacitive-touch, Single Zone LCD, AirCommand and CCC2 products can assign codes differently.

E2: indoor temperature sensor open or out of range

E2 means the CCC2 cannot read a valid indoor-temperature-sensor circuit because it is open or outside its accepted range. Heating and cooling are locked out in that zone, while manual fan operation can continue.

Look for an unplugged remote room sensor, damaged small-gauge wire or a loose connection at accessible low-voltage points. Sensor resistance and module-board testing should follow Dometic service information for the installed configuration.

E3: indoor temperature sensor shorted

E3 also concerns the indoor temperature sensor, but the circuit is read as shorted. Heat and cool are locked out and manual fan may remain available. Pinched wire, moisture in a connector or failed sensor can create the condition.

Because E2 and E3 represent opposite electrical states, swapping parts without checking the harness can waste time. Inspect the full accessible path before condemning the thermostat or module.

E4: outdoor temperature sensor open or out of range

E4 applies to select heat-pump models. Heat-pump operation is locked out because the system cannot judge outdoor temperature, but air conditioning, furnace, heat strip and fan modes can continue.

If cooling still works, that is consistent with the code. Check for storm or service damage near the rooftop sensor wiring, but avoid removing the shroud unless roof access and electrical isolation are safe.

E5: freeze sensor open or out of range

E5 means the evaporator freeze-sensor circuit is open or outside range. Air-conditioning operation is locked out to protect the coil; heat pump, furnace, heat strip and fan can remain available.

A sensor displaced from the evaporator, a broken lead or a poor connector can produce E5. Do not jumper the sensor. The control needs a valid sensor before normal cooling should resume.

Know the nearby CCC2 codes

  • E7: loss of 120V AC power to all system power-module boards.
  • E8: invalid zone configuration with heat-pump and heat-strip DIP switches both selected.
  • E9: invalid dehumidifier and heat-pump/heat-strip configuration.

E8 and E9 commonly follow module replacement or DIP-switch changes. Dometic requires a system reset after configuration changes.

Use the reset at the right time

After an accessible connection is reseated or a configuration is corrected, power the CCC2 down completely. Dometic’s setup reset uses the Mode and Zone buttons to display IniT and rediscover available zones. Do not reset first if you have not recorded the original code.

Difficulty and repair boundary

  • Owner checks: record code/zone, inspect accessible low-voltage plugs and confirm which modes still work.
  • Moderate: exact CCC2 reset after a known correction.
  • Technician: rooftop sensor access, resistance testing, module-board diagnosis and DIP-switch configuration.
  • Useful evidence: code, zone, available modes and whether the fault began after service or a storm.

Related RV Solver pages

Frequently asked questions

What does Dometic CCC2 E5 mean?

E5 means the freeze-sensor circuit is open or out of range. Air-conditioning operation is locked out while several other modes may remain available.

Can I run my Dometic AC with an E4 code?

The CCC2 manual says E4 locks out heat-pump operation on select models, while air conditioning and other listed modes can continue. Confirm the exact thermostat and equipment before relying on that behavior.

Will resetting the CCC2 fix E2 or E3?

A reset may clear a temporary connection event, but a persistent open or shorted indoor-sensor circuit needs wiring, connector or sensor diagnosis. Record the code before resetting.

Still narrowing it down?

The guided troubleshooter walks through the symptom in a safe order and points you toward the right RV system.

Open the troubleshooter

Sources and review notes

Reviewed against manufacturer material on July 12, 2026. Match every procedure, limit and replacement part to the exact model, serial range and manual installed in the RV.