Q: Cooling capacity drops, interior temperature rises

Possible cause: Vaporiser iced over, ambient temperature too high, insufficient ventilation, or condenser dirty / fan defective. Defrost vaporiser, relocate cooling device for better airflow, clean condenser, or replace defective fan.

Question 1

UKL = 0 V (Interruption in the connection between battery and electronics)

Accepted Answer

Possible cause: Interruption in the connection line battery - electronics, main switch faulty, or additional supply line fuse blown. Establish connection, replace main switch, or replace supply line fuse.

Question 2

UKL <= UON (Battery voltage too low during start attempt)

Accepted Answer

Possible cause: Battery voltage too low, loose cable connection, poor contact (corrosion), cable cross-section too small, or battery capacity too low. Charge battery, establish connection/clean contacts, replace cable with correct cross-section, or replace battery.

Question 3

UKL >= UON (Compressor fails to run, high ambient temp)

Accepted Answer

Possible cause: Ambient temperature too high, insufficient ventilation, or condenser dirty. Move refrigerator to a better-ventilated location and clean the condenser.

Question 4

Compressor runs continuously

Accepted Answer

Possible cause: Thermostat sensor has no contact on evaporator, short circuit in thermostat line, thermostat defective, or evaporator iced over. Secure sensor, change thermostat, defrost vaporiser, or adjust/replace drawer seal.

Question 5

Loud humming

Accepted Answer

Possible cause: Refrigerant circuit component cannot move freely (touching wall) or foreign body jammed between cooling unit and wall. Carefully bend the component away from the obstruction or remove the foreign body.

Question 6

Reception interference during compressor operation

Accepted Answer

Possible cause: Electronic connection of the cooling device is not directly clamped on to the battery. Connect the cooling device as directly as possible to the poles of the battery.

Question 7

Compressor does not run (UKL = 0 V)

Accepted Answer

Possible cause: Interruption in connection line between battery and electronics, or defective main switch, or blown additional supply line fuse. Establish proper connection, replace main switch, or replace line fuse.

Question 8

Compressor does not run (UKL <= UIN)

Accepted Answer

Possible cause: Battery voltage too low, loose cable connections, poor contact/corrosion, battery capacity too low, or cable cross-section too small. Charge battery, secure connections, eliminate corrosion, replace battery, or replace cable with appropriate cross-section based on cable length.

Question 9

Compressor runs constantly

Accepted Answer

Possible cause: Thermostat sensor has no contact to vaporiser, or thermostat defective, or short circuit in thermostat line. Secure thermostat sensor to vaporiser or replace thermostat.

Question 10

Cooling capacity drops, interior temperature rises

Accepted Answer

Possible cause: Vaporiser iced over, ambient temperature too high, insufficient ventilation, or condenser dirty / fan defective. Defrost vaporiser, relocate cooling device for better airflow, clean condenser, or replace defective fan.

Question 11

Loud humming noise

Accepted Answer

Possible cause: Component of refrigerant circuit cannot move freely and touches the wall, or foreign body jammed between cooling machine and wall. Carefully bend the component away from the wall or remove the foreign body.

Question 12

Compressor does not run (UKL <= U_ON / Start attempt with UKL <= U_OFF)

Accepted Answer

Possible cause: Batteries voltage too low, loose cable connection, poor contact/corrosion, insufficient battery capacity, or too small cable cross section.. Charge the battery, clean and secure cable connections, replace the battery, or upgrade cable cross-section according to manual charts.

Question 13

Compressor does not run (Start attempt with UKL >= U_ON)

Accepted Answer

Possible cause: Ambient temperature too high, insufficient ventilation, dirty condenser, defective fan, or compressor defect.. Relocate the freezer for better airflow, clean the condenser, replace the fan, or replace the compressor.

Question 14

Cooling performance drops, interior temperature increases

Accepted Answer

Possible cause: Evaporator iced over, ambient temperature too high / poor ventilation, dirty condenser, defective fan, or exhausted battery capacity.. Defrost the vaporiser, relocate unit for proper ventilation, clean the condenser, replace the fan, or charge the battery.

Question 15

Unusual noises (Loud humming or rattling)

Accepted Answer

Possible cause: Refrigerant circuit component cannot move freely and touches the wall, or a foreign body is jammed between the cooling unit and the wall.. Carefully bend the component away from the obstruction or remove the jammed foreign body.

Question 16

Compressor does not run due to low battery voltage (UKL <= UCON)

Accepted Answer

Possible cause: Insufficient battery capacity, loose cable connection, corroded contacts, or insufficient cable cross-section. Charge battery, tighten connections, clean corrosion, or replace cable according to the length/cross-section specification chart.

Question 17

Compressor does not run due to high ambient temperature / thermal overload

Accepted Answer

Possible cause: Insufficient ventilation, dirty condenser, or defective fan. Relocate unit for better airflow, clean the condenser, or replace the fan.

Question 18

Cooling capacity decreases / interior temperature increases

Accepted Answer

Possible cause: Evaporator iced up, high ambient temperature, poor ventilation, dirty condenser, or dead battery. Defrost the evaporator, improve ventilation, clean the condenser, or charge the battery.

Question 19

Abnormal noises (loud buzzing)

Accepted Answer

Possible cause: Refrigeration circuit component touching the wall and unable to vibrate freely, or foreign objects trapped between unit and wall. Carefully bend the component away from the wall or remove foreign objects.

Question 20

Appliance does not heat (MH07)

Accepted Answer

Possible cause: Interruption in connection line, blown fuse, or insufficient battery voltage. Check wiring, replace fuse, or charge the battery.

Question 21

Compressor does not run (Battery voltage UZ = 0)

Accepted Answer

Possible cause: Break in connection cable between battery and electronic module, defective main switch, or blown inline fuse.. Restore connection, replace main switch, or replace inline fuse.

Question 22

Compressor does not run (Battery voltage UZ <= UVKL)

Accepted Answer

Possible cause: Battery voltage too low, loose cable connection, poor contact/corrosion, battery capacity too low, or cable cross-section too small.. Charge battery, restore connection, replace battery, or replace cable with correct cross-section.

Question 23

Compressor runs continuously or long

Accepted Answer

Possible cause: Evaporator iced up, high ambient temperature, inadequate ventilation, dirty condenser, or thermostat sensor not in contact with evaporator.. Defrost evaporator, improve ventilation, clean condenser, replace fan if applicable, or secure thermostat sensor contact.

Question 24

Water inside or under the refrigerator

Accepted Answer

Possible cause: Blocked drain channel or stored food touching the back wall and interfering with water runoff.. Clean the drain channel using the cleaning tool and ensure food items do not touch the rear wall.

Question 25

The device does not work.

Accepted Answer

Possible cause: An on-board 12/24 V socket (cigarette lighter) in the vehicle is not live.. In most vehicles, the ignition switch must be switched on for the cigarette lighter to have voltage.

Question 26

The device does not work.

Accepted Answer

Possible cause: Alternating voltage socket is not live.. Try using another plug socket.

Question 27

The device does not work.

Accepted Answer

Possible cause: The fuse of the 12/24 V plug has blown.. Replace the 10 A fuse in the 12/24 V plug.

Question 28

The device does not work.

Accepted Answer

Possible cause: The vehicle fuse for the 12/24 V socket has blown.. Replace the vehicle socket fuse (typically 15 A, refer to vehicle operating manual).

Question 29

The device does not work with ignition on.

Accepted Answer

Possible cause: The cigarette lighter socket is dirty, causing poor electrical contact.. Clean the socket or check if the plug is assembled correctly.

Question 30

Refrigerator switches off unexpectedly or fails to start.

Accepted Answer

Possible cause: Battery protection monitor tripped due to low input voltage (below 11.3V for 12V or 24.6V for 24V).. Charge the vehicle battery or ensure proper charging cycles before operating the refrigerator.

Question 31

Refrigerator does not cool effectively after initial installation.

Accepted Answer

Possible cause: Unit was not allowed to settle in a horizontal position prior to operation or ventilation is obstructed.. Keep the refrigerator in a horizontal position for approximately 1 hour before switching on and ensure proper clearance/ventilation around the unit.

Question 32

Compressor does not run (UKL = 0 V / UMO = 0 V)

Accepted Answer

Possible cause: Interruption in connection line between battery and electronics, or blown inline fuse. Establish connection or replace inline fuse

Question 33

Compressor does not run due to low voltage (UKL ≤ UCON / UMO ≤ UON)

Accepted Answer

Possible cause: Insufficient battery capacity, loose cable connection, poor contact/corrosion, or insufficient cable cross-section. Charge battery, tighten/repair connections, replace battery, or replace cable with correct cross-section based on length

Question 34

Cooling capacity reduced / interior temperature increases

Accepted Answer

Possible cause: Evaporator iced up, ambient temperature too high, insufficient ventilation, or dirty condenser. Defrost evaporator, improve ventilation/relocate unit, or clean the condenser

Question 35

Compressor does not run (Supply voltage U_Z = 0)

Accepted Answer

Possible cause: Open circuit in the connection cable between battery and electronic module, defective main power switch, or blown additional inline fuse.. Restore connection, replace main switch, or replace inline fuse.

Question 36

Compressor does not run (Supply voltage U_Z <= U_ON)

Accepted Answer

Possible cause: Battery voltage too low, loose cable connection, poor contact/corrosion, battery capacity too low, or cable cross-section too small.. Charge battery, restore connection, clean/tighten contacts, replace battery, or replace cable with correct cross-section.

Question 37

Compressor does not run (Supply voltage U_Z >= U_ON, high ambient temperature)

Accepted Answer

Possible cause: Insufficient ventilation, dirty condenser, or defective fan.. Relocate refrigerator for better ventilation, clean condenser, or replace fan.

Question 38

Compressor runs continuously or too long

Accepted Answer

Possible cause: Thermostat sensor has no contact with evaporator, thermostat line short-circuited, thermostat defective, large amount of warm food frozen at once, iced-up evaporator, insufficient ventilation, or dirty condenser.. Secure thermostat sensor, replace thermostat, defrost evaporator, improve ventilation, or clean condenser.

Question 39

Water flows inside refrigerator or onto floor

Accepted Answer

Possible cause: Clogged condensation drain channel, food items touching the back wall, or too much water in the air-guiding plate.. Clean the drain channel using the integrated cleaning tool, rearrange food to prevent wall contact, or clean the air-guiding plate.

Question 40

Loud humming / Unusual noises

Accepted Answer

Possible cause: Refrigerant circuit component touching a wall or foreign object jammed between cooling unit and wall.. Carefully bend the component away from the wall or remove the foreign object.

Question 41

The device does not work (No power)

Accepted Answer

Possible cause: No voltage present in the 12/24 V socket (cigarette lighter) in the vehicle because ignition is switched off.. Turn on the ignition switch in the vehicle to supply current to the cigarette lighter.

Question 42

The device does not work (AC mains)

Accepted Answer

Possible cause: AC voltage socket leads no voltage.. Try using another plug socket.

Question 43

Plug becomes very warm during 12/24 V operation

Accepted Answer

Possible cause: The cigarette lighter socket is dirty resulting in poor electrical contact, or the plug is not assembled correctly.. Clean the cigarette lighter socket or check/reassemble the plug.

Question 44

Device does not work and 12/24 V plug fuse is blown

Accepted Answer

Possible cause: Plug fuse has blown.. Replace the fuse (10 A) in the 12/24 V plug.

Question 45

Device does not work and vehicle fuse is blown

Accepted Answer

Possible cause: Vehicle fuse for the 12/24 V socket has blown.. Replace the vehicle-side 12/24 V socket fuse (typically 15 A).

Question 46

Cooling unit does not operate (with ignition off)

Accepted Answer

Possible cause: Supply voltage has fallen below the battery monitor cutout threshold (11.3 V at 12 V / 24.6 V at 24 V). Recharge the vehicle battery to reach the restart voltage threshold (12.5 V at 12 V / 26.0 V at 24 V)

Question 47

Cooler switches off automatically / fails to run on battery

Accepted Answer

Possible cause: Supply voltage dropped below the cut-off threshold due to battery discharge. Recharge the vehicle battery and check terminal connections. Ensure the vehicle ignition is on or battery monitor settings match operational needs.

Question 48

Cooling performance drops / insufficient cooling

Accepted Answer

Possible cause: Restricted air circulation or covered ventilation slots. Ensure sufficient distance to walls and objects, clear ventilation slots, and remove heat buildup from around the compressor.

Question 49

Compressor does not run (UKL <= UCON / UMO <= UON with low battery voltage)

Accepted Answer

Possible cause: Insufficient battery voltage, loose cable connection, poor contact (corrosion), insufficient battery capacity, or insufficient cable cross-section. Charge battery, check and tighten connections, replace battery, or replace cable with correct cross-section according to manual length/gauge chart

Question 50

Compressor runs continuously / cooling capacity reduces

Accepted Answer

Possible cause: Evaporator iced up, ambient temperature too high, insufficient ventilation, dirty condenser, or defective fan. Defrost the evaporator, improve unit location/ventilation, clean the condenser, or replace the fan

Question 51

Abnormal noises (loud humming)

Accepted Answer

Possible cause: Refrigeration circuit component cannot vibrate freely (touching wall) or foreign bodies trapped between cooler and wall. Carefully bend component to clear the wall or remove foreign objects

Question 52

Compressor does not run (Supply voltage U_Z >= U_ON, start attempt fails due to thermal limits)

Accepted Answer

Possible cause: Ambient temperature too high, insufficient ventilation, dirty condenser, defective fan. Relocate refrigerator, clean condenser, replace fan

Question 53

Compressor runs continuously / too long

Accepted Answer

Possible cause: Thermostat sensor lacks contact with evaporator, thermostat line short-circuit/defective thermostat, large quantity of food frozen at once, frosted evaporator, dirty condenser, defective fan. Secure sensor, replace thermostat, defrost evaporator, clean condenser, replace fan

Question 54

Water inside the refrigerator or on the floor

Accepted Answer

Possible cause: Drain channel clogged, stored food touching rear wall, too much water in air guide plate. Clean drain/water channel, ensure food does not touch rear wall, clean air guide plate

Question 55

Unusual noises (Loud humming)

Accepted Answer

Possible cause: Refrigerant circuit component cannot vibrate freely (touches wall), foreign objects jammed between cooling unit and wall. Carefully bend component, remove foreign objects

Question 56

The device does not work with ignition on when connected to 12/24 V socket.

Accepted Answer

Possible cause: The cigarette lighter socket is dirty, causing poor electrical contact.. Clean the socket or check if the plug is assembled correctly (if the plug becomes very warm).

Question 57

The device does not work with ignition on when connected to 12/24 V socket.

Accepted Answer

Possible cause: The fuse of the 12/24 V plug has blown.. Replace the fuse (10 A / 8A 32V) in the 12/24 V plug.

Question 58

The device does not work with ignition on when connected to 12/24 V socket.

Accepted Answer

Possible cause: The vehicle fuse has blown.. Replace the vehicle's 12/24 V socket fuse (usually 15 A, refer to vehicle operating manual).

Question 59

Refrigerator switches off automatically

Accepted Answer

Possible cause: Battery protection triggered due to low supply voltage.. Charge the vehicle battery or check input connections.

Question 60

Refrigerator does not cool

Accepted Answer

Possible cause: Incorrect temperature setting or appliance switched off.. Turn temperature regulator to the right to switch on and set lower temperature.

Question 61

Poor cooling performance / overheating

Accepted Answer

Possible cause: Blocked ventilation openings or inadequate heat dissipation.. Clear ventilation slots and ensure sufficient clearance around the appliance.

Question 62

Compressor does not run (UKL=0 Volt)

Accepted Answer

Possible cause: Interruption in the connection supply line, main switch defective, additional supply line fuse blown. Check and repair wiring, replace defective switch or fuse

Question 63

Compressor does not run (UKL ≤ UON)

Accepted Answer

Possible cause: Battery voltage too low, loose cable connection/corrosion, cable cross section too small, battery capacity too low. Charge battery, clean/secure connections, use correct cable cross-section

Question 64

Compressor runs continuously / for a long time

Accepted Answer

Possible cause: Thermostat sensor has no contact to vaporiser, short circuit in thermostat line, thermostat defective, large quantities frozen, vaporiser iced over, insufficient insulation, ambient temperature too high, insufficient ventilation, condenser dirty. Secure thermostat sensor, change thermostat, defrost vaporiser, adjust or replace drawer seal, ensure adequate ventilation, clean condenser, replace defective fan

Error Code / Indicator	Symptom / Meaning	Step-by-Step DIY Fix	Suggested Actions
`N/A`	UKL = 0 V (Interruption in the connection between battery and electronics) Possible Cause: Interruption in the connection line battery - electronics, main switch faulty, or additional supply line fuse blown	Establish connection, replace main switch, or replace supply line fuse.	DIY Safe
`N/A`	UKL <= UON (Battery voltage too low during start attempt) Possible Cause: Battery voltage too low, loose cable connection, poor contact (corrosion), cable cross-section too small, or battery capacity too low	Charge battery, establish connection/clean contacts, replace cable with correct cross-section, or replace battery.	DIY Safe
`N/A`	UKL >= UON (Compressor fails to run, high ambient temp) Possible Cause: Ambient temperature too high, insufficient ventilation, or condenser dirty	Move refrigerator to a better-ventilated location and clean the condenser.	DIY Safe
`N/A`	Compressor runs continuously Possible Cause: Thermostat sensor has no contact on evaporator, short circuit in thermostat line, thermostat defective, or evaporator iced over	Secure sensor, change thermostat, defrost vaporiser, or adjust/replace drawer seal.	DIY Safe
`N/A`	Loud humming Possible Cause: Refrigerant circuit component cannot move freely (touching wall) or foreign body jammed between cooling unit and wall	Carefully bend the component away from the obstruction or remove the foreign body.	DIY Safe
`N/A`	Reception interference during compressor operation Possible Cause: Electronic connection of the cooling device is not directly clamped on to the battery	Connect the cooling device as directly as possible to the poles of the battery.	DIY Safe
`N/A`	Compressor does not run (UKL = 0 V) Possible Cause: Interruption in connection line between battery and electronics, or defective main switch, or blown additional supply line fuse	Establish proper connection, replace main switch, or replace line fuse.	DIY Safe
`N/A`	Compressor does not run (UKL <= UIN) Possible Cause: Battery voltage too low, loose cable connections, poor contact/corrosion, battery capacity too low, or cable cross-section too small	Charge battery, secure connections, eliminate corrosion, replace battery, or replace cable with appropriate cross-section based on cable length.	DIY Safe
`N/A`	Compressor runs constantly Possible Cause: Thermostat sensor has no contact to vaporiser, or thermostat defective, or short circuit in thermostat line	Secure thermostat sensor to vaporiser or replace thermostat.	DIY Check / Tech Fallback
`N/A`	Cooling capacity drops, interior temperature rises Possible Cause: Vaporiser iced over, ambient temperature too high, insufficient ventilation, or condenser dirty / fan defective	Defrost vaporiser, relocate cooling device for better airflow, clean condenser, or replace defective fan.	DIY Safe
`N/A`	Loud humming noise Possible Cause: Component of refrigerant circuit cannot move freely and touches the wall, or foreign body jammed between cooling machine and wall	Carefully bend the component away from the wall or remove the foreign body.	DIY Safe
`N/A`	Compressor does not run (UKL <= U_ON / Start attempt with UKL <= U_OFF) Possible Cause: Batteries voltage too low, loose cable connection, poor contact/corrosion, insufficient battery capacity, or too small cable cross section.	Charge the battery, clean and secure cable connections, replace the battery, or upgrade cable cross-section according to manual charts.	DIY Safe
`N/A`	Compressor does not run (Start attempt with UKL >= U_ON) Possible Cause: Ambient temperature too high, insufficient ventilation, dirty condenser, defective fan, or compressor defect.	Relocate the freezer for better airflow, clean the condenser, replace the fan, or replace the compressor.	DIY Check / Tech Fallback
`N/A`	Cooling performance drops, interior temperature increases Possible Cause: Evaporator iced over, ambient temperature too high / poor ventilation, dirty condenser, defective fan, or exhausted battery capacity.	Defrost the vaporiser, relocate unit for proper ventilation, clean the condenser, replace the fan, or charge the battery.	DIY Check / Tech Fallback
`N/A`	Unusual noises (Loud humming or rattling) Possible Cause: Refrigerant circuit component cannot move freely and touches the wall, or a foreign body is jammed between the cooling unit and the wall.	Carefully bend the component away from the obstruction or remove the jammed foreign body.	DIY Safe
`N/A`	Compressor does not run due to low battery voltage (UKL <= UCON) Possible Cause: Insufficient battery capacity, loose cable connection, corroded contacts, or insufficient cable cross-section	Charge battery, tighten connections, clean corrosion, or replace cable according to the length/cross-section specification chart.	DIY Safe
`N/A`	Compressor does not run due to high ambient temperature / thermal overload Possible Cause: Insufficient ventilation, dirty condenser, or defective fan	Relocate unit for better airflow, clean the condenser, or replace the fan.	DIY Check / Tech Fallback
`N/A`	Cooling capacity decreases / interior temperature increases Possible Cause: Evaporator iced up, high ambient temperature, poor ventilation, dirty condenser, or dead battery	Defrost the evaporator, improve ventilation, clean the condenser, or charge the battery.	DIY Safe
`N/A`	Abnormal noises (loud buzzing) Possible Cause: Refrigeration circuit component touching the wall and unable to vibrate freely, or foreign objects trapped between unit and wall	Carefully bend the component away from the wall or remove foreign objects.	DIY Safe
`N/A`	Appliance does not heat (MH07) Possible Cause: Interruption in connection line, blown fuse, or insufficient battery voltage	Check wiring, replace fuse, or charge the battery.	DIY Safe
`N/A`	Compressor does not run (Battery voltage UZ = 0) Possible Cause: Break in connection cable between battery and electronic module, defective main switch, or blown inline fuse.	Restore connection, replace main switch, or replace inline fuse.	DIY Safe
`N/A`	Compressor does not run (Battery voltage UZ <= UVKL) Possible Cause: Battery voltage too low, loose cable connection, poor contact/corrosion, battery capacity too low, or cable cross-section too small.	Charge battery, restore connection, replace battery, or replace cable with correct cross-section.	DIY Safe
`N/A`	Compressor runs continuously or long Possible Cause: Evaporator iced up, high ambient temperature, inadequate ventilation, dirty condenser, or thermostat sensor not in contact with evaporator.	Defrost evaporator, improve ventilation, clean condenser, replace fan if applicable, or secure thermostat sensor contact.	DIY Check / Tech Fallback
`N/A`	Water inside or under the refrigerator Possible Cause: Blocked drain channel or stored food touching the back wall and interfering with water runoff.	Clean the drain channel using the cleaning tool and ensure food items do not touch the rear wall.	DIY Safe
`N/A`	The device does not work. Possible Cause: An on-board 12/24 V socket (cigarette lighter) in the vehicle is not live.	In most vehicles, the ignition switch must be switched on for the cigarette lighter to have voltage.	DIY Safe
`N/A`	The device does not work. Possible Cause: Alternating voltage socket is not live.	Try using another plug socket.	DIY Safe
`N/A`	The device does not work. Possible Cause: The fuse of the 12/24 V plug has blown.	Replace the 10 A fuse in the 12/24 V plug.	DIY Safe
`N/A`	The device does not work. Possible Cause: The vehicle fuse for the 12/24 V socket has blown.	Replace the vehicle socket fuse (typically 15 A, refer to vehicle operating manual).	DIY Safe
`N/A`	The device does not work with ignition on. Possible Cause: The cigarette lighter socket is dirty, causing poor electrical contact.	Clean the socket or check if the plug is assembled correctly.	DIY Safe
`N/A`	Refrigerator switches off unexpectedly or fails to start. Possible Cause: Battery protection monitor tripped due to low input voltage (below 11.3V for 12V or 24.6V for 24V).	Charge the vehicle battery or ensure proper charging cycles before operating the refrigerator.	DIY Safe
`N/A`	Refrigerator does not cool effectively after initial installation. Possible Cause: Unit was not allowed to settle in a horizontal position prior to operation or ventilation is obstructed.	Keep the refrigerator in a horizontal position for approximately 1 hour before switching on and ensure proper clearance/ventilation around the unit.	DIY Safe
`N/A`	Compressor does not run (UKL = 0 V / UMO = 0 V) Possible Cause: Interruption in connection line between battery and electronics, or blown inline fuse	Establish connection or replace inline fuse	DIY Safe
`N/A`	Compressor does not run due to low voltage (UKL ≤ UCON / UMO ≤ UON) Possible Cause: Insufficient battery capacity, loose cable connection, poor contact/corrosion, or insufficient cable cross-section	Charge battery, tighten/repair connections, replace battery, or replace cable with correct cross-section based on length	DIY Safe
`N/A`	Cooling capacity reduced / interior temperature increases Possible Cause: Evaporator iced up, ambient temperature too high, insufficient ventilation, or dirty condenser	Defrost evaporator, improve ventilation/relocate unit, or clean the condenser	DIY Safe
`N/A`	Compressor does not run (Supply voltage U_Z = 0) Possible Cause: Open circuit in the connection cable between battery and electronic module, defective main power switch, or blown additional inline fuse.	Restore connection, replace main switch, or replace inline fuse.	DIY Safe
`N/A`	Compressor does not run (Supply voltage U_Z <= U_ON) Possible Cause: Battery voltage too low, loose cable connection, poor contact/corrosion, battery capacity too low, or cable cross-section too small.	Charge battery, restore connection, clean/tighten contacts, replace battery, or replace cable with correct cross-section.	DIY Safe
`N/A`	Compressor does not run (Supply voltage U_Z >= U_ON, high ambient temperature) Possible Cause: Insufficient ventilation, dirty condenser, or defective fan.	Relocate refrigerator for better ventilation, clean condenser, or replace fan.	DIY Check / Tech Fallback
`N/A`	Compressor runs continuously or too long Possible Cause: Thermostat sensor has no contact with evaporator, thermostat line short-circuited, thermostat defective, large amount of warm food frozen at once, iced-up evaporator, insufficient ventilation, or dirty condenser.	Secure thermostat sensor, replace thermostat, defrost evaporator, improve ventilation, or clean condenser.	DIY Check / Tech Fallback
`N/A`	Water flows inside refrigerator or onto floor Possible Cause: Clogged condensation drain channel, food items touching the back wall, or too much water in the air-guiding plate.	Clean the drain channel using the integrated cleaning tool, rearrange food to prevent wall contact, or clean the air-guiding plate.	DIY Safe
`N/A`	Loud humming / Unusual noises Possible Cause: Refrigerant circuit component touching a wall or foreign object jammed between cooling unit and wall.	Carefully bend the component away from the wall or remove the foreign object.	DIY Safe
`N/A`	The device does not work (No power) Possible Cause: No voltage present in the 12/24 V socket (cigarette lighter) in the vehicle because ignition is switched off.	Turn on the ignition switch in the vehicle to supply current to the cigarette lighter.	DIY Safe
`N/A`	The device does not work (AC mains) Possible Cause: AC voltage socket leads no voltage.	Try using another plug socket.	DIY Safe
`N/A`	Plug becomes very warm during 12/24 V operation Possible Cause: The cigarette lighter socket is dirty resulting in poor electrical contact, or the plug is not assembled correctly.	Clean the cigarette lighter socket or check/reassemble the plug.	DIY Safe
`N/A`	Device does not work and 12/24 V plug fuse is blown Possible Cause: Plug fuse has blown.	Replace the fuse (10 A) in the 12/24 V plug.	DIY Safe
`N/A`	Device does not work and vehicle fuse is blown Possible Cause: Vehicle fuse for the 12/24 V socket has blown.	Replace the vehicle-side 12/24 V socket fuse (typically 15 A).	DIY Safe
`N/A`	Cooling unit does not operate (with ignition off) Possible Cause: Supply voltage has fallen below the battery monitor cutout threshold (11.3 V at 12 V / 24.6 V at 24 V)	Recharge the vehicle battery to reach the restart voltage threshold (12.5 V at 12 V / 26.0 V at 24 V)	DIY Safe
`N/A`	Cooler switches off automatically / fails to run on battery Possible Cause: Supply voltage dropped below the cut-off threshold due to battery discharge	Recharge the vehicle battery and check terminal connections. Ensure the vehicle ignition is on or battery monitor settings match operational needs.	DIY Safe
`N/A`	Cooling performance drops / insufficient cooling Possible Cause: Restricted air circulation or covered ventilation slots	Ensure sufficient distance to walls and objects, clear ventilation slots, and remove heat buildup from around the compressor.	DIY Safe
`N/A`	Compressor does not run (UKL <= UCON / UMO <= UON with low battery voltage) Possible Cause: Insufficient battery voltage, loose cable connection, poor contact (corrosion), insufficient battery capacity, or insufficient cable cross-section	Charge battery, check and tighten connections, replace battery, or replace cable with correct cross-section according to manual length/gauge chart	DIY Safe
`N/A`	Compressor runs continuously / cooling capacity reduces Possible Cause: Evaporator iced up, ambient temperature too high, insufficient ventilation, dirty condenser, or defective fan	Defrost the evaporator, improve unit location/ventilation, clean the condenser, or replace the fan	DIY Check / Tech Fallback
`N/A`	Abnormal noises (loud humming) Possible Cause: Refrigeration circuit component cannot vibrate freely (touching wall) or foreign bodies trapped between cooler and wall	Carefully bend component to clear the wall or remove foreign objects	DIY Safe
`N/A`	Compressor does not run (Supply voltage U_Z >= U_ON, start attempt fails due to thermal limits) Possible Cause: Ambient temperature too high, insufficient ventilation, dirty condenser, defective fan	Relocate refrigerator, clean condenser, replace fan	DIY Check / Tech Fallback
`N/A`	Compressor runs continuously / too long Possible Cause: Thermostat sensor lacks contact with evaporator, thermostat line short-circuit/defective thermostat, large quantity of food frozen at once, frosted evaporator, dirty condenser, defective fan	Secure sensor, replace thermostat, defrost evaporator, clean condenser, replace fan	DIY Check / Tech Fallback
`N/A`	Water inside the refrigerator or on the floor Possible Cause: Drain channel clogged, stored food touching rear wall, too much water in air guide plate	Clean drain/water channel, ensure food does not touch rear wall, clean air guide plate	DIY Safe
`N/A`	Unusual noises (Loud humming) Possible Cause: Refrigerant circuit component cannot vibrate freely (touches wall), foreign objects jammed between cooling unit and wall	Carefully bend component, remove foreign objects	DIY Safe
`N/A`	The device does not work with ignition on when connected to 12/24 V socket. Possible Cause: The cigarette lighter socket is dirty, causing poor electrical contact.	Clean the socket or check if the plug is assembled correctly (if the plug becomes very warm).	DIY Safe
`N/A`	The device does not work with ignition on when connected to 12/24 V socket. Possible Cause: The fuse of the 12/24 V plug has blown.	Replace the fuse (10 A / 8A 32V) in the 12/24 V plug.	DIY Safe
`N/A`	The device does not work with ignition on when connected to 12/24 V socket. Possible Cause: The vehicle fuse has blown.	Replace the vehicle's 12/24 V socket fuse (usually 15 A, refer to vehicle operating manual).	DIY Safe
`N/A`	Refrigerator switches off automatically Possible Cause: Battery protection triggered due to low supply voltage.	Charge the vehicle battery or check input connections.	DIY Safe
`N/A`	Refrigerator does not cool Possible Cause: Incorrect temperature setting or appliance switched off.	Turn temperature regulator to the right to switch on and set lower temperature.	DIY Safe
`N/A`	Poor cooling performance / overheating Possible Cause: Blocked ventilation openings or inadequate heat dissipation.	Clear ventilation slots and ensure sufficient clearance around the appliance.	DIY Safe
`N/A`	Compressor does not run (UKL=0 Volt) Possible Cause: Interruption in the connection supply line, main switch defective, additional supply line fuse blown	Check and repair wiring, replace defective switch or fuse	DIY Safe
`N/A`	Compressor does not run (UKL ≤ UON) Possible Cause: Battery voltage too low, loose cable connection/corrosion, cable cross section too small, battery capacity too low	Charge battery, clean/secure connections, use correct cable cross-section	DIY Safe
`N/A`	Compressor runs continuously / for a long time Possible Cause: Thermostat sensor has no contact to vaporiser, short circuit in thermostat line, thermostat defective, large quantities frozen, vaporiser iced over, insufficient insulation, ambient temperature too high, insufficient ventilation, condenser dirty	Secure thermostat sensor, change thermostat, defrost vaporiser, adjust or replace drawer seal, ensure adequate ventilation, clean condenser, replace defective fan	DIY Safe
`N/A`	Cooling capacity drops, interior temperature rises Possible Cause: Vaporiser iced over, insufficient insulation, ambient temperature too high, insufficient ventilation, condenser dirty, fan defective, battery capacity exhausted	Defrost vaporiser, adjust/replace seal, provide adequate ventilation, clean condenser, replace fan, charge battery	DIY Check / Tech Fallback
`N/A`	Loud humming noise Possible Cause: A component of the refrigerant circuit cannot move freely, component is touching wall/foreign body	Move the component carefully into a free position	DIY Safe
`N/A`	Radio or television interference in the vehicle Possible Cause: Electronic connection of the cooling device is not directly clamped on to the battery	Connect the cooling device as directly as possible to the battery poles	DIY Safe

Dometic CoolMatic

Technical Specifications

Master Troubleshooting & Diagnostics Matrix

Frequently Asked Questions

Q: What does climate class of SN (Sub Normal) mean?

Q: What’s the cooling performance in warmer ambient temperatures?

Q: How to operate an RMxxxx with a solar panel?

Q: My RMxxxx needs to be replaced. What would be an alternative?

Q: The refrigerator does not work In AC power mode?

Q: The refrigerator does not work In DC power mode?

Q: The refrigerator does not work In GAS mode?

Q: In automatic mode: The refrigerator is being operated with gas although it is connected to The AC power supply?

Q: The refrigerator is not cooling adequately?

Q: WARNING type fault messages

Q: ERROR type fault messages