[dr_jonno]

Re: Fixing a KGV3120GB/01

I’m happy to report that the fix did work. The temp control dial does now do something again – ie turn it up and the compressor kicks in.
The fridge and freezer seems to be at healthy temperatures.
I would agree that it makes most sense that there are two sensors in the fridge. HOWEVER, with the fridge door open I only saw one sensor resistance drop. This was the one I shorted out and I assume is in the insulation at the back…. If the other sensor were also in the fridge I would have expected to see it change too.
If anyone knows for sure where these sensors are I’d be interested to hear.
Thanks

[dr_jonno]

Re: Fixing a KGV3120GB/01

My bosch kvg3120gb/01 seems to have the usual problem too – gets very warm (>0C in the freezer) before the compressor kicks in.
I have followed the threads about the fixes and found the information contradictory in many places.
Here is what I have found, and my reasoning. Hope it helps someone.

On this 4 wire connector there ARE small numbers (1 to 4) on the face where the wires go in. I have
1-light blue
2-dark blue
3-dark brown
4-light brown

unplug the connector (squeeze the clip to allow it to release). If you look at resistances between the pins on the circuit board with a multimeter, you’ll see zero ohms between the pins where the blue wires go. ie these are common, so must be ground. so the BLUE WIRES ARE GROUND.

I have seen the thermistors desctibed as NTC (nagative temp coefficient). THis means the resistance is high when cold, and goes down as they warm up. So when the modification talks about shorting two wires out (ie zero ohms), it is telling the control that the thermistor is WARM.

My reasoning says that if shorting the thermistor out is a working fix, then the contol board must think ‘if both thermistors are warm then put the compressor on’. In other words, the fix tells the control that one thermistor is always warm, and the compressor should come on when the other thermistor says ‘I’m warm’.

With the connector unplugged, I measured:
12k ohms between 4 and 2, light brown and dark blue
1M ohm, dropping to 30k ohms over 5 mins with the fridge door open between pins 1 and 3, light blue and dark blue.
So the fridge thermistor must be connected between pins 1 and 3.

Perhaps I should have waited longer with the door open to see if the fridge thermistor dropped any lower – the fix would suggest that this thermistor is unable to go below the value needed to make the control think the fridge is warm.
With the fridge thermistor changing, I dubious that this fix will work – I would expect a dead thermistor to be open circuit, ie very high resistance, but I figured I’ve nothing to loose. I’ve switched on and the compressor has kicked in so we’ll see.

What I am confused about is why the ‘fix’ seems to focus on just one thermistor. Surely either of them could be faulty? In which case you could short out either 1 and 3 (fridge) or 2 and 4 (freezer).

I would be very grateful if someone who knows what is going on could reply to some of these questions. Thanks

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