Liebherr fridge not cooling despite Triac/Resistor fix. Freezer works.

Hi @glebloumer

Did you check if the refrigerator compartment light turns off by manually operating the door switch with the door open?

Can't find out if it is a hidden magnetic reed switch or an overt mechanical switch as to find the correct part the refrigerator's serial number is required.

If it is a magnetic reed switch, usually these switches are located somewhere along the top edge of the door frame.

You can either use a magnet and run it along the door frame to see if this operates/releases the switch i.e light turns off and on etc or set a mobile phone to record video and then place it inside the compartment and close the door then after about 5 seconds of recording open the door and check the video to see if the light turned off

Reason is that the door switch controls the evap fan as it is turned off when the door is opened so that no cold air is deliberately blown out.

Given the faults it might be the board not switch

Thanks @jayeff, will check that.

Having said that, meanwhile the same triac is again blown. Since it is the one driving the magnetic valve of the coolant circuit my theory is that this valve is defective / stuck. Does that make sense?

If yes, can the valve be repaired or is replacement the only option?

And what is the replacement process, since there are coolant pipes going into that valve,

Test of switching valve shorting the triac; if a third triac is installed, disconnect wiring to the valve and turn power on. Without the valve electrically connected, the triac should not short again. Insofar as replacing the valve, I see three copper tubes with caps on a site's parts list. This requires refrigeration expertise in repairs (copper brazing) as described by jayeff (below). Presuming you're in Europe, there may be restrictions of diy repairs of releasing r600a, isobutane (cigarette lighter) or reclaiming refrigerant into a canister (requiring all the refrigeration equipment professional services use). An initial search shows conflicting rules in America about releasing r600a into the atmosphere without harm to the environment or reclaiming it into canisters for reuse or disposal. The small amount of r600a in refrigerators may be permissible for release no different from using a cigarette lighter without igniting it. The flammable gas is handled/ventilated carefully. Lastly, consider repair costs.

Thanks All! When I was measuring the valve coil resistance, I noticed thet the resistance value gradualy went up. Upon the expection of the connector between the board and the valve coil I relaized that it was contaminated by mice, so that the 2 wires actually had a 200k Ohm connection. After cleaning the connector, the valve coil gave a stable 5kOhm reading.

So this fehlt like a good explanation for the blown triac and I actually thought the valve might be ok and i might have gotten to the bottom of it. I exchanged the triac again, waited for the freezer to get to target temperature... Still the refrigerator compartment is warm... and I also lost the lights in both fridge and refrigerator compartments.

The door switch appears to be working since I was getting an alarm after the fridge door was open for a few minutes. The exchanged triac holds so far.

Any ideas where to take it from here?

@glebloumer

Where did you test the fridge sensor from, the connections on the board or at the sensor itself?

If at the sensor, check for continuity from the board to the sensor.

If OK and if it is possible as a check, swap the freezer and temp sensor wires at the control board.

If the board is faulty the freezer should be warm and the fridge cold you would think. A lot of the times the same model sensor is used for both locations