Bosch KAN62V41GB / 02 Freezer not cooling

Hi,

I have a Bosch KAN62V41GB (American style) which is now 3 years old. The freezer has stopped cooling and has risen to about 10degC despite setting of -18degC. The fridge continues to work and sits at the set 4degC.

I’ve been working through a whole lot of tests and doing a bit of research on the internet. Unfortunately I’m coming to the end of things to try and would appreciate some advice from people more experienced in fridge freezers.

I’m very practical and have a lot of experience DIY fixing white goods so I’m happy to try things people can suggest.

The unit was £1100 so I’m reluctant to throw it out but also cautious about pouring money into something which could be uneconomical to fix.

Here’s what I have tried so far:
1. Thermistor in top of freezer evaporator measures 6K Ohms at room temp and reduces with increased temp. Can’t find any other thermostat/thermistor in the freezer compartment. When high temp alarm sounds the display reported freezer temp (10degC) is accurate to a separate thermometer I used. So I concluded temp measurement in freezer is reading OK.
2. Thermal fuse on freezer evaporator measures close to 0 Ohms so no problem there.
3. Fridge and freezer fans run when door switches pressed.
4. No build up of ice on fridge or freezer evaporators.
5. Condenser cleaned and dust free. Condenser fan running and adequately cooling condenser.
6. Compressor running and output pipe getting warm-ish.
7. Freezer evaporator gets cold but not freezing cold. Bit of frost around capillary pipe entering evaporator.
8. No fault codes from self test (Hold – & + buttons for 5 sec to start).
9. PCB in top of unit visually appears ok. Two relays are clicking and switching 240V on/off during startup – not sure what they are driving though.
10. Diverter valve (feeding two capillary pipes) clonks a few times during power up sequence. My guess is that this is switching refrigerant between fridge and freezer. Not sure which way is the default position though. Measured voltage across this is about 150VAC when active despite the part being rated for 240VAC. Not been able to locate where this is being driven from. The neutral is permanently connected to the mains input neutral and the live is switched.

Things remaining on my list:
A. Compressor weak or lacking gas (no DIY possible)
B. Blockage in pipe (no DIY possible).
C. Diverter valve failed or not being switched correctly (Maybe I can find where it is driven from and find the missing 100VAC or alternatively wire it to a permanent live to test operation. No DIY replacement of valve possible)

Thanks for reading my post and I look forward to some advice.

Thanks,
Stu