To be a bit more specific, I've got a 20-ish year old Liebherr that has just stopped working. This was quite a sophisticated beast for its time. It's a twin compressor model, and you set the desired temperatures of the fridge and freezer parts from a couple of little control panels above the door. It displays the actual temps on some eight segment displays there, flashing if it's working to get to where you want it. There's a control board with a microprocessor on it that read the temperature from a couple of sensors, switches the compressors on as necessary, and runs the display. There's also a Supercool button if you want an extra boost. I think that this is a timed boost unrelated to actual temp. After all, the compressor has only one speed.
Now the fridge has just stopped working. It's displaying 11, which seems to be the highest temp you can set the fridge (clearly the designer was a Spinal Tap fan), and if I try to adjust it, it flicks straight back to 11. If however I press the supercool button, the compressor starts up, the back of the fridge gets cold, and the number on the display changes to reflect the actual internal temperature.
I checked the motor capacitor on my meter and it is showing 2.46uF, against a spec value of 2.5. Probably better than any new one I could get. The start up relay looks fine (it's one of those little round ceramic discs), and both must be working because I can force the compressor to start. The temp sensor seems to be working because the display reports the actual temp when I've got the supercool button on. I've had the PCB out, everything looks OK, no bulged capacitors or burnt resistors. No fault codes are showing. If there was a leak then surely the compressor would not work at all. I don't think the overheat sensor sends any feedback to the MCU.
I suspect that it's not fixable, but even so my pride is hurt. I don't like throwing stuff out without knowing for sure how and why it broke. Does anyone have any thoughts?
Now the fridge has just stopped working. It's displaying 11, which seems to be the highest temp you can set the fridge (clearly the designer was a Spinal Tap fan), and if I try to adjust it, it flicks straight back to 11. If however I press the supercool button, the compressor starts up, the back of the fridge gets cold, and the number on the display changes to reflect the actual internal temperature.
I checked the motor capacitor on my meter and it is showing 2.46uF, against a spec value of 2.5. Probably better than any new one I could get. The start up relay looks fine (it's one of those little round ceramic discs), and both must be working because I can force the compressor to start. The temp sensor seems to be working because the display reports the actual temp when I've got the supercool button on. I've had the PCB out, everything looks OK, no bulged capacitors or burnt resistors. No fault codes are showing. If there was a leak then surely the compressor would not work at all. I don't think the overheat sensor sends any feedback to the MCU.
I suspect that it's not fixable, but even so my pride is hurt. I don't like throwing stuff out without knowing for sure how and why it broke. Does anyone have any thoughts?
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