Liebherr Freezer Service Mode

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Introduction

The aim of this guide, is to give some information on the service mode of a Liebherr GN 3356 freezer. This information may be relevant to other similar models.

WARNINGS

I am not, and do not profess to be a refrigeration engineer, I have gained some knowledge of this simply be reading information online, and from a number of YouTube videos posted by a variety of people. Please be mindful of this before attempting to work on any refrigeration appliances as a result of reading this.

Some of the service modes will directly control the various components of the freezer like the defrost heater, the compressor, the fan and the light - leaving some of these items on for longer than their design specification could cause damage, overheating, and possibly even a fire, these modes are used at your own risk.

Why You Might Need This

The reason I needed this was to test both the defrost heater and the fan, following the freezer being left slightly open (but not enough to activate the alarm on it) which caused the fan to frost up, and the freezer to then not chill the contents, despite it ruining the compressor (because the fan appeared to have been frozen). I ran a manual defrost, and also firmly banged the underside of the evaporator unit inside the appliance at the top (with my hand), this unstuck the fan and returned it to normal operation) I did this with the fan test mode selected when this mode did not result in the fan running, but my power meter showing it was drawing about 5 watts, so it was clearly taking power, but appeared to be jammed.

Tools You Might Need

For general testing, you will not need any tools, however, a power monitor that shows the power consumption of the appliance would be handy so you can check to see if the fan, defrost heater and compressor are consuming power. A popular brand of these is a "Kill a Watt" but there are loads on the market. They simply plug into a normal wall socket, then you connect the item you want to test to it.

Entering Service Mode

With the freezer in normal operation, hold both the On/Off button and the Super Frost button for approx. 5 seconds until the display flashes "H"

Manual Defrost Mode

To activate the manual defrost, enter the service menu, press the Super Freeze button in the "H" mode, and the display will then show "A" This mode will now run until the temperature sensor in the evaporator unit (inside at the top of the freezer) gets to 32°C OR after 50 minutes of operation (as I understand it, I have tested neither fully) Once this cycle has completed, the freezer will return to normal operation automatically. To abort this mode, hold the power button until the appliance turns off, then turn it back on again.

Sensor Readings

There are three sensors in this unit... 1. The internal temperature sensor, where the food is stored 2. The evaporator temperature (the unit at the top inside the freezer) 3. The door sensor

To get into sensor reading mode, go into the service mode, then use the up or down arrow button to select "E" and press the Super Frost button You can now use the up and down arrows to show the three sensors

E3 - Internal Temperature (In °C)

E4 - Evaporator Temperature (In °C)

E8 - Door status (0 = Door closed & 1 = Door Open

While viewing any of these three sensors, the display will cycle between the mode it is in, and the reading.

To exit this mode press the power button

Test Modes

This mode allows you to turn on various items in the appliance directly for testing purposes, please note, these should NOT be left on for extended periods of time, as damage may occur, for example, leaving the defrost heater on for too long would probably be a bad idea.

To enter this mode, enter the service mode, then scroll to the "L" mode using the up or down button, then press the Super Frost button. Once in the mode, the display will show "rd" Now you muse open the door and close it, which will turn on all elements of the display to show they are working, and also the super Frost button will illuminate.

Now you must test all the buttons by pressing them one by one.

When this is complete, the unit will emit a long beep, and display "L0" - you are now in test mode. You can cycle through all the test modes with the up or down arrow button.

L0 is everything (except the display) off - in this mode, if you are monitoring the power consumption, it will be showing zero, or near zero.

L1 will turn just the compressor on, so the power draw will be around 150w (* note 1)

L3 will turn just the internal fan on, so the power consumption will be about 5w

L4 will turn just the defrost heater on, so the power consumption will be about 240w (*note 2)

L5 will turn just the light on, so the power consumption will be about 15w

note 1 - When the compressor is selected, if the compressor had been running just before you entered this test mode (which will turn the compressor off) the compressor may draw over 1 KW for a short rime, then trip out. This happens because the compressor does not have enough power to start when there is too much pressure on the output stage, this needs to dissipate, and the thermal cut-out in the compressor reset before it will try again - this is totally normal, and nothing to worry about, so if this happens, just leave it in this mode for a while (probably between 5 and 10 minutes) and it will try again, and then the compressor should run.

note 2 - Do not leave the defrost heater on for long while testing, or you might melt something inside the freezer. If the freezer is working normally, and the evaporator temperature is nice and low, then 5 minutes or so should be fine, however if the freezer is not cold inside, this may be too long, and may cause the temperature in the evaporator unit to get too high to test it, you should only need it on for a short time to see the consumption.

To exit this mode press the power button once

Demo Mode

This mode is usually used on a shop, so the display will show, the light inside will work, but the unit will not actually get cold.

To enable demo mode, enter the service mode then use the up or down arrow button to select "d1" and press Super frost The freezer will now show -18, but the compressor, defrost heater and circulation fan will not run.

To exit this mode, go back into service mode, and select "d0" and press Super Frost - the display will revert to normal operation, showing the actual temperature.

please note, you must turn demo mode off again manually, powering the appliance off and on will not clear this mode.


--Toby... 23:45, 9 February 2018 (GMT)

See also