Dometic single zone lcd thermostat troubleshooting
Troubleshooting

Dometic single zone LCD thermostat troubleshooting

November 25, 2019

Your Single Zone LCD thermostat is equipped with both a liquid crystal display (LCD) that relays temperature set-point, fan speed signal(Auto, Low, High) and green LEDs indicating the mode of operation (Off, Fan, Cool, Furnace, Heat Pump or Heat Strip). The modes depending on the system installed in your RV

How do I reset my Dometic Single Zone LCD thermostat?

Your Dometic Single Zone LCD thermostat comes pre-programmed. However, you need to review its settings and make necessary adjustments to your preferences.

To turn On the Single Zone LCD thermostat,

  • Press the On/Off Mode button.(The LCD will be activated).
  • Press the On/Off Mode button to turn Off the Single Zone LCD thermostat
  • Toggle through the modes until the On/Off green LED is on.
  • The LCD will go out and the green LED will remain on for approximately 15 seconds,
  • Go out.

Mode Selection

  • Press the On/Off Mode button to go to the available modes.
  • Press to advance to available mode.
  • The green LED will indicate the mode selected either (Off, Fan, Cool, Furnace, Heat Pump or Heat Strip)

Inside Temperature

To display the Inside Temperature your thermostat should be in Off Mode.

  • Press either the “+” or “―” button to show  the Inside Temperature

Fan Speed Press the On/Off Mode button until the fan green LED is lit.

The LCD will show

  • “Lo” (Low),
  • “Hi” (High)  o
  • “Au” (Auto).

Press the “+” or “―” button to select the desired fan speed.

Temperature Set-Point

The temperature set-point is indicated by two digits on the LCD. The maximum set-point for the system is 90º F. The minimum set-point is determined by the active operating mode whereby for heating, the minimum is 40º F and 55ºminimum for cooling.

  • Press the “+” to increase and the “―” to decrease the temperature set point.

Off

When Off Mode selected, the LCD will go blank. The Off green LED will turn on for 15 seconds, then go off.

Cool

Cool mode is selected to make the system cycle the compressor On and Off based on the room air temperature and the temperature set-point.

The fan will turn on then followed by the compressor in roughly 2 minutes. There are 3 fan speed selections in this mode:

  • Au – (AUTO): The fan speed alternates depending on the difference between the temperature set-point and the room air temperature. The compressor and the fan cycle On and Off with the thermostat.
  • Hi – (HIGH): The fan operates continuously at high speed. The compressor cycles ON and OFF
  • Lo – (LOW): The fan operates continuously at low speed. The compressor usually cycles ON and OFF.

Furnace Mode

There are 3 fan speed selections for this mode:

  • Lo – (LOW): The fan operates continuously at low speed.
  • Hi – (HIGH): The fan operates continuously at high speed.
  • Au – (AUTO): The fan will be OFF.

The manufacturer advises in case of additional indoor air circulation provided by the air conditioner is not desired during Furnace Mode of operation, select Au (AUTO) in the Fan Mode to shut the air conditioner fan off.

In the FURNACE mode, the system cycles the furnace On and Off based on the room air temperature and the temperature.

You can configure the system to operate using On/Off differential of 1 or 2 degree F.

To  set the temperature differential the system

  • Ensure our thermostat is Off.
  • Press the “―” button.
  • while holding it, also press and hold the On/Off Mode button for three seconds.
  • Release the On/Off Mode button.
  • Then release the “―”
  • Press the “+” button to toggle between “d1” and “d2”, “d1” for 1 degree F differential and “d2” for 2 degrees F differential.

Heat Pump mode

In the Heat Pump mode, the system cycles the compressor On and Off based on the room air temperature and the temperature set point.

The system delays for approximately two minutes while adjusting to the surrounding temperature.

In auto fan, the compressor will turn  On first followed by the fan in approximately 15 seconds.

In this mode there are 3 fan speed selections:

  • Lo – (LOW): The fan operates continuously at low speed.

The compressor cycles ON and OFF.

  • Hi – (HIGH): The fan operates continuously at high speed. The compressor cycles ON and OFF.
  • Au – (AUTO): When auto fan is selected the fan speed will vary depending on the difference between the temperature set-point and the room temperature. In auto fan the compressor and fan will cycle On and      Off      with     the

Heat Strip Mode (Select Models)

In the Heat Strip mode, the system cycles the heat strip On and Off based on the room air temperature and the temperature setpoint.

In this mode there are 3 fan speed selections:

  • Lo – (LOW): The fan operates continuously at low speed. The heat strip cycles On and Off.
  • Hi – (HIGH): The fan operates continuously at high speed. The heat strip cycles On and Off.
  • Au – (AUTO): The fan operates in low speed and will cycle On and Off with the thermostat.

Fan Mode

In Fan mode there are 3 fan speed selections:

  • Lo – (LOW): The fan operates continuously at low speed.
  • Hi – (HIGH): The fan operates continuously at high speed.
  • Au – (AUTO): The fan will be Off.

How do I initialize a Dometic Thermostat?

You will need to perform a system initialization after the system installation.

  • Ensure your thermostat is Off.
  • Press the“+” button and, while holding it, also press and hold the On/Off Mode button for three seconds.
  • LCD will show ― ―.
  • Press the On/Off Mode button again to turn the system off.
  • This completes the initialization.

The furnace On/Off temperature differential should be set at this time.

Dometic thermostat won’t turn on

In case your thermostat won’t turn on here is how to solve the problem.

  • Ensure the main power is switched on
  • switched on the thermostat
  • Reset the thermostat circuit breaker
  • If the thermostat comes on but does not provide temperature control, switch it to a lower temperature than its operating tempera
  • Wait for ten minutes and turn it back on to the previous temperature.
  • If the steps above do not work, reset the thermostat according to its instruction manual.
  • Switch off power and check the wiring.
  • If the problem persists, contact customer care

How to change Dometic single-zone LCD thermostat from Celsius to Fahrenheit

Simultaneously press the “+” and “―“ buttons to toggle between Fahrenheit and Centigrade format. ºF indicates Fahrenheit and ºC indicates Centigrade

LCD Error Code display when the system determines and lists faults. Some of these faults are.

Error Code: E1 Results from a loss of communication between the Single Zone LCD thermostat and its module board. LCD will cycle between E1 and the previous mode setting. The system eventually shuts down.

E2 Open circuit or out of range Indoor Temperature Sensor. Heating and cooling operation will be locked out. Fan operation can continue to operate despite the lockout.

E3 Shorted Indoor Temperature Sensor. Heating and cooling operation will be locked out however, fan operation continues.

E4 Open circuit or out of range Outdoor Temperature Sensor (select models). Heat Pump operation will be locked out. Other operations like Air Conditioner, Fan and Furnace operation continue to operate.

E5 Open circuit or out of range Freeze Sensor. The air conditioner mode of operation will be locked out. Furnace, heat strip, heat pump and fan mode of operation can continue to operate but give a wrong display of the last temperature set-point.

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