Liebherr integrated IK3510 larder fridge – recurring F2 issue

[truckbusuk]

Good afternoon, I’d like a step for a hint on the following problem I have with our Liebherr IK3510 integrated larder fridge.

The fridge is approx 7 years old, and last year we had an F2 error (the fridge was freezing everything,) a local Liebherr authorised service agent replaced the condenser plate sensor after much faffing about, no parts, account hold, engineer on holiday etc, etc

Well 6 months later the same F2 error reocurred. This time I looked at the sensor, and to my horror the previous repair consisted of the old sensor being cut off approx 60mm from the sensor tip, and a new sensor wired in ….. well twisted bare wires in fact.

I soldered and insulated the “previous repair” and all was good for approx another 6 months, then the F2 error reocurred (same symptoms,) assuming it was the iffy repair again I sourced a Liebherr repair kit and following the instructions to the letter replaced the whole sensor assembly. On powering up the fridge is still displaying the F2 error. The fridge is operating I guess in emergency mode as it is cold but not at 6° as set, but at least it is not freezing everything.

So what is the issue this time a step for a hint from you much more knowledgeable chaps than me would be appreciated … there does not seem to be much in the circuit except the sensor and the controller board … could it be the controller that’s the problem this time?

I apologise for the long winded post.

thanks Robin

[Tony R]

You have not put the index number of your unit, but Liebherr appear to only have produced this model in version index 001 ranging from 20 to 20F, however they all have the same sensor part number, so I would be interested in the sensor part number that you bought and fitted.

[truckbusuk]

Hi, sorry didn’t have notifications switched on … the fridge info is …

It’s a Liebherr build in larder fridge.
Service-Nr 9981488-00
Model IK3510 Index 20/001
Serial-Nr 30.323.196.5

I will post the part number I eventually sourced in the morning.

Thanks Robin

[truckbusuk]

Hello again, part numbers …. I was advised by Liebherr UK technical support the correct part number for the evaporator sensor was 9590182.

I spoke with Ken Watt, and at that time (early August) he was unable to source the part, no UK nor factory stock and no eta.

I eventually found the part on the web and ordered the kit, what was supplied and fitted was Liebherr – 9590182/015 sealed in a several poly bags.

Kit consisted of:-
evaporator sensor
strain relief cover
2 cable retainers
red spring holder for the sensor
heat shrink tubing
back casing foam seal
2 tywraps
silicone putty
aluminium foil tape
instruction sheet

Cheers Robin

[Tony R]

Hi Robin,
You got the right part, I know the sensor cable on that version is foamed into the wall, the repair is to cut off the old sensor, fit the new sensor in the metal pocket on the evaporator plate and feed the new sensor cable out the cabinet via the refrigeration pipe entry hole and re join it to the old sensor cable at the rear of the unit, this is to prevent the join from getting wet and malfunctioning, an F2 fault indication is always down to the sensor having failed or a poor connection/join.

[truckbusuk]

Thanks Tony, do you think the new sensor may be faulty?, I did put a meter on it and it is giving a reading, I would have expected if it was goosed then I would be 0. … I did cut the old sensor as per the instructions and shrink wrapped the old connector, but the new sensor is intact all the way to the controller ….

I wonder if the connector is not making good enough contact to the board ?

[Tony R]

The resistance gets higher the colder the sensor is reading, for instance the resistance in Ohm at +20c is 5.9 at +15c its 7.3

[truckbusuk]

Hi Tony, I got the following on testing the sensor (power off.)

8.63 ohm @ 12°
10.75 ohm @ 8°
15.44 ohm @ 5°
Condenser plate temp during the measurements was between -0.75° and +2.36°

I also notice when the fridge is first powered up, the temperature the fridge is set to shows on the display ie 6° but after 20 seconds it then shows F2.

So from above I assume the sensor is operating correctly.

Again your help is appreciated.
Robin

[Tony R]

Hi Robin, you state temperatures of -0.75 and +2.36 on plate when taking resistance but then post readings at higher temperatures.
A reading at +5c should be 11.9 Ohms, at 0c it is 15.3 Ohms, you got a reading of 5c at 15.44 Ohms, allowing for a slight rise during testing I suspect the sensor is fine, however the board is telling us something different, in that the sensor is not being located by the board or not making a good connection or is indeed failing.

[truckbusuk]

Hi, thanks, I shall rephrase … I admit it was a bit confusing …

The internal cavity temp @ 12° the sensor reading was 8.63 ohm
The internal cavity temp @ 8° the sensor reading was 10.75 ohm
The internal cavity temp @ 5° the sensor reading was 15.44 ohm
Condenser plate temp during the measurements varied between -0.75° and +2.36° as it cooled to small condensation drops that were almost frozen, then thawed back to water droplets , sorry I should have measured the plate with each reading.

So from what you are saying am I correct in thinking that the sensor seems ok, but the controller board is not interperating the sensor properly? … could the new sensor be faulty? … or do I have a board issue?

Re the board, the ventilation function works ok, the supercool function works ok, the temp set function appears to work ok as it scrolls through the temperatures.
The board connector marked with a green line appears to make good contact, and I slightly crimped the connector to make better contact … still shows F2. the connector is connected to the LHS/top connector point (depending on board orientation) with a black/white and red identifier.

Is there anything else I can/should check, or is this pointing to the controller board?

Thanks again Robin

[Tony R]

Hi Robin,
You need to take your temperature readings at the sensor tip where it is sited on the evaporator plate and check your resistance, your issue is either the sensor at fault or the board not recognising it is connected to it, this can be the only two reasons for the fault indication F2. In fault mode the unit cycles between 30 minutes on to 30 minutes off.

[truckbusuk]

Again thanks Tony, I shall take the temp readings at the tip of the sensor. Will be a couple of days before I can strip the fridge down as I’m a bit tied up at work at the moment, but I will report back.

Thanks Robin

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