Hello folks, help with KGU3201GB/01 please

[Optimist?]

Good morning.

I recently acquired a misbehaving fridge freezer (Bosch KGU3201GB/01) from my mother, thinking I’d be able to fix it and replace my even older unit.

On arrival I took various bits apart, and found that there was a blockage in the ‘frost free’ drainage hole bit, mysterious shreds of blue hard plastic??? Removing these I patted myself on the back for having found something that might explain mum’s observation that from time to time the alarm would go off ‘cos the freezer section was warming up unhelpfully. No error codes were displayed. I’ve read the FAQ on how these ‘frost free’ things work, and have checked what I can and found nothing obvious.

Edit, forgot to say, it was OK for about 6 days, then got the freezer warming up all by itself problem yesterday, 🙁 . Mum reckoned that if you power down for a few hours, then back on, it’s OK for a while, and it was like this for me too. To me that suggests the fundamentals might be OK? More of a ‘control’ prob?

I’m quite handy and knowledgeable about electronics, so if anyone thinks these symptoms can be explained by a control PCB problem, I’ll be in there trying to fix it. I’m a ‘fix what you’ve got’ type guy, and tend to be optimistic about mending rather than replacing things.

Anyone care to encourage me? 🙂

TIA,

Pete

[helo_75]

Re: Hello folks, help with KGU3201GB/01 please

unless of course the thermistors faulty,,,, and thats foamed in, so itll be a skip job

[gegsy]

Re: Hello folks, help with KGU3201GB/01 please

Hi
Four thermisters/NTCs, in the appliance.
If any of the thermisters were faulty you would get an error code, so they can be disregarded.
Most likely is a defrost circuitry fault or main PCB 263782 £103.90 inc VAT +costs.
To be a 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} I would get an engineer in to confirm the fault as there are test procedures that will confirm the fault.
Please feel free to find an engineer from the link below.
Greg

[Optimist?]

Thanks for the replies

Thank you both for replying.

I agree that a ‘hardware’ fault with the defrost circuitry (basically two heaters and a fan, right?) would seem to be consistent with the observed fault. With plug out of the wall, and each of these three components unplugged, I’ve already measured resistances in the hundreds/low thousands (IIRC) of ohms region for these which sounds better than open-circuit or short-circuit. I can measure these resistances more accurately if anyone knows what the approx. ‘correct’ figures are.

Then, I’m thinking, if hardware seems OK in freezer compartment , get my way into the PCB area (yup, plug out of the wall), and see if there are any visual clues of burnt out components, or capacitors with bulgy/leaking cans.

Point taken about contacting engineer, and thanks for the links.

Cheers for help,

Pete

[Optimist?]

More questions

Haven’t had a chance to do any more with the ‘old girl’, except to witness it misbehaving again on Sat. night. The freezer compartment once again started warming up, but the fridge stayed at set temp (+5). Alarm started sounding some time during the night, and the freezer section was up to about -5 degrees C by morning, luckily we’d moved all the frozen stuff back into the old(er!) machine. The freezer part continued to warm slowly all the way up to ambient, but the fridge remained at +5. Powered down for two hours Sun. eve, then back on again, and the freezer’s sitting happily at -18 again now.

Noticed the fan turning when I opened the freezer door on Sun morning, so that works! There was no ice build-up at all on the freezer ‘radiator’ or whatever it’s called. This suggests to me that either a defrost heater is staying on when it should have gone off, or for some reason the refrigerant is not getting into the freezer part at all times when it should.

Can’t really figure out how the fridge part gets its ‘chillin’, nor the function of the (?) solenoid valve down near the compressor. Does this switch the flow of refrigerant between fridge and freezer? If so I guess it could be sometimes sticking in the wrong position…

Sorry to write such essays, just one more thing…
What a pain in the bum that on this machine if you change the door hinges round to the LHS (which i did as soon as i got it, without thinking), you then have to take the doors off to get to the control PCB!

Any suggestions welcomed, please educate me 🙂

Pete

[Optimist?]

Re: Hello folks, help with KGU3201GB/01 please

Hello again,

Some progress, but still some questions outstanding, and a new one.

Just had the doors off in order to get to the PCB(s), plug out of wall of course. Whilst removing the doors my g/f noticed that the ‘middle bit’ between the doors, i.e. the floor of the fridge/ceiling of freezer, was warm to the touch along its front edge. This surprised us both. I attempted to remove the trim panel covering this area, but without success, but could see in well enough to see no wiring or anything behind there. (So that’s the new question, why is that area getting warm?)

Thorough inspection of the main control PCB revealed nothing amiss. Electrolytic capacitors all seem OK (visually, and with a tan-delta meter), diodes all check out OK, no burnt out conventional or SM components.
I’m thinking that’s a good PCB, though without a schematic, hard to test more fully. No reason to think the display PCB has any issues, so didn’t even inspect that.

So back to the questions of how my fridge part gets its cooling (‘cos I see no passages for cold air to be ducted up into it, just the one drain hole at its rear). And secondly, perhaps relatedly, what does the solenoid valve (?) at the back, to the right of the compressor (looking at the rear, from the rear) do? If this does alternate the flow of refrigerant ‘tween fridge section and freezer section, then it sticking in the ‘cool the fridge’ position could explain why my freezer sometimes warms up, but the fridge is always OK.

Edit 19:58 Aha! Are the two things with plastic ‘grills’ over them, the cold air ducts I should have seen? One at the very bottom rear of the freezer section, the other just above the first shelf, LHS of fridge? I’d assumed they were covers over thermistor temp. sensors…

I guess one other possibility is that the starter capacitor for the compressor is ‘on its way out’, anyone experienced that, with this model? That couldn’t explain the fact the fridge section keeps set temperature even when the freezer comes all the way up to ambient though, I don’t think.

Wisdom please, anyone. 🙂

Pete

[nomadPaul]

Re: Hello folks, help with KGU3201GB/01 please

the area between the doors is ‘warmed’ to stop the freezer door from freezing shut . This is normal

[Optimist?]

Re: Hello folks, help with KGU3201GB/01 please

Oh, I see!

Thanks nomadPaul, that’s a very helpful reply. I would never have thought of that. One less thing to worry about 😆 .

Pete

[Optimist?]

Cunning plan?

Had another idea, think it might be a good ‘un.

If I unplug the unit at the wall, then take the cover off the freezer’s internals, then unplug both defrost heaters. I’ll probably be able to tell after a week (‘cos it’s going into a ‘fail’ situation every 4 or 5 days at the mo) whether it’s:

1. The defrost heater(s) staying on when they shouldn’t be (‘cos they’ll not be on at all), or
2. Inadequate cooling in the freezer radiator for some reason, every few days.

As far as I can see, one or other of these things is the only explanation for my symptoms of everything being fine most of the time, then a warming up freezer section, fridge temperature at set-point. Obviously the freezer section’s gonna tend to ice up during this experiment, but that isn’t a problem, ‘slong as I keep an eye on it.

I expect many of you are thinking “why doesn’t he just get an engineer in?” It’s not out of disrespect for anyone, or particularly about the cash, I just like figuring things out for myself (but as you can see, I’m very happy to get friendly help!).

Pete

[Optimist?]

Update, 1 week on

Expect you’re all fed up of hearing from me, but never mind.

One week on from disconnecting the de-frost heaters and all is well.

To me this suggests (still) two possibilities.

1. The defrost heaters were staying on when they shouldn’t have been on. This seems unlikely, as I believe all the ‘tronics controlling their action is solid-state, and less likely to have an intermittent fault than say a relay with dirty/worn contacts. I’d expect the power devices on the PCB that energise these heaters to either work when asked to, or have failed forever…But open to suggestion if anyone knows better. 🙂

2. The defrost heating was causing the compressor (additional workload), or indirectly (via radiated heat?) the solenoid valve to go into a fail/stuck state. Likely?

As ever, all suggestions/assistance gratefully received,

Pete

[Optimist?]

More info

Hello all,

More info today. For the first time since unplugging the defrost heaters, the freezer started warming up again. This coincided with my girlfriend forgetting which freezer to put stuff in (should’ve been the old one), and loading the freezer with unfrozen ‘ice-packs’ ready for a camping trip (!)

This does suggest that it’s the additional ‘system load’, not the defrost heaters themselves that is the problem. Girlfriend’s just told me the temperature is now dropping quite rapidly again, with no power off/on, just by removing the ice packs.

So it’s looking like the compressor is struggling, probably due to old age. I shall try putting a small fan, operated off a 12V d.c wall-wart PSU adjacent to the compressor to help it out (keep it’s temp. down a bit). I admit that this is a longshot, but have nothing to lose. Daily operating costs for such a fan will be about 1p if that. (Also could be loss of R600a I guess, which would be beyond my rectification)

I’m bracing myself for ridicule, but have broad shoulders, so if anyone really feels the need to vent their spleen at me, just go for it. Bear in mind who’s likely to sound silliest though.

Still hoping some kind, knowledgable person will help me to understand what the solenoid valve down near the compressor does. 🙂

Pete

[Mike-in-Horwich]

Re: Hello folks, help with KGU3201GB/01 please

I shall try putting a small fan, operated off a 12V d.c wall-wart PSU adjacent to the compressor to help it out (keep it’s temp. down a bit). I admit that this is a longshot, but have nothing to lose. Daily operating costs for such a fan will be about 1p if that.

💡

Music to my ears Pete.

In my (limited) experience 😆 a 12v d.c. fan sorts every known fridge problem. Can I also suggest you consider using an ex-PC fan as this recycling is most beneficial to the environment.

Mike

😉

[Penguin45]

Re: Hello folks, help with KGU3201GB/01 please

Noted, M-in-H.

Penguin45.
Moderator.

[chas1203]

Re: Hello folks, help with KGU3201GB/01 please

Hi, I have read the numerous entries regarding your efforts to resolve your issue – with basically no comprehension of what you are talking about!! However, it seems to me that the way to resolve your issue was to place some sort of fan in the working parts.
My mum has the same model and for some time now it has been shutting down. I do not live close enough to monitor the siuation and my mum is often out or asleep when the problem arises. The problem seems to happen when there is a drop in temperature in the kitchen/ house. The problem did not happen during the summer (did happen previous winter) and does not happen when the central heating is left on. She recently left the F/F switched off while she was away for 2 weeks (I noticed a lot of recommendations to power off) but this had has no effect. Is this in anyway related to your problem? Is there a fix which doesn’t involve an engineer or should she just replace it?
Thanks

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