Fridge Freezer - Freezing in the fridge. BUSH BFFF54170

[colinregan]

Hi,
We have a 6ft tall Fridge Freezer, 50/50 split.
Its a Bush BFFF54170, about 5 years old.
There seems to be a few people with simliar issues on similar fridge/freezers, different brands.
The fridge compartment is getting too cold, and freezing some of the items.
We have had a few exploded cans of coke (I'll take a picture of the mess next time it happens), and a few solid cartons of milk.
Ive adjusted the thermostat to "warmest" setting (1) but no different.
In a few places Ive seen people say "switch it off for a bit". I tried that, but no different.
I've not left it off for 24hrs or longer yet, I'll maybe try that next, but need to empty the freezer section first !

I have replaced the electronic thermostat, cost £40, see photo, and an easy job to do (20 mins) once you find the part (search for "20BD01-6") and no change.



Somewhere else I read an article about the freezer section having a seperate thermostat, but I dont think this unit has such. If you know different, please let me know. It said if the freezer is too cold, that carries up into the above fridge.
Ive checked and cleaned everywhere else too, like air vents and things.

Anybody got any ideas.

Cheers. Colin.

 

[JohnD]

is it a frost-free freezer, and does it have ducts/vents in the back wall for cold air to blow between the two chambers?

have you got a thermometer? What are the temperatures in the fridge and the freezer section?

if the ducts are choked with ice, it takes a lot longer than "a bit" for the blockage to melt and drip out.

 

[colinregan]

Hi JohnD.

Yes its advertised as a "Frost-Free" fridge/Freezer.
I dont have a thermometer, but I could probably get one cheap if necessary.
Im not sure about vents/ducts between the top and bottom chambers.
Would these be visible inside the fridge ? All I can see is a v-shape channel with a small hole, which I thought was for water droplets run off, through a hole to outside at the back. I can take a picture of inside the fridge iif it helps. That hole seems clear too.

Cheers.

 

[colinregan]

Hi John,

I've read a few of your other messages related to similar problems. Thanks for posting so much useful advice.

So, I emptied my fridge and freezer, and switched it off for three days, with the doors open.
Some water came out the back, but a not a lot.
It was in the garage, and the ambient temp was 20C, so Im fairly sure everything would have defrosted.
I switched it back on, and within a few hours it was back to freeezing in the freezer and the fridge chilling very cold.
The rear cooling panel in the fridge (heat exchanger ?) created solid frozen water droplets on it.
I got some temp meters, and set them up. I also put an ice-cream box of water on middle shelf, near back of fridge.
Next day, the water was solid, and the firdge temp was -0.2C, with the freezer at -28.2C. See images (top meter is fridge).



That is very cold for the freezer too.
The thermostat was set at "1", the warmest, so we tried it at "5" (coldest) for another day, but no difference.
Its back at "1" again.

Ive already tried a new thermostat circuit board. No difference.
So, Im wondering, is there possibly a faulty temp sensor which feeds into the circuit board?
PL802 looks like it migth be some sort of sensor input.
Any ideas if that be replaced ?

The fridge/freezer is obviously very good at chilling and freezing, so the issue seems to be with temp regulation.
It seems an awful waste to have to scrap and replace it.
We have had a few solid cartons of milk, and exploded cans of coke, from the fridge. I must take a photo of the mess that makes, if it happens again !

Any guidance would be appreciated.

Cheers, Colin.

 

[JohnD]

Yes, there must surely be a temperature sensor but I don't know where.

Can you find an exploded parts diagram?

Does your machine have "fast freeze" or "super" setting? Maybe that has got jammed on.

 

[colinregan]

Hi JohnD.

I'll have to hunt for such a diagram. I was hoping someone on here migth help in finding such.
Or in finding a temp probe item which would be a fit for this unit.
I only got the circuit board by taking the eixisting one out.
Searching for the model "Bush XYZ" doesn't get to many specific components beyond drawers and shelves.
I guess that is because there is a lot of common parts across many brands.

The freezer section has four drawers, with the top drawer, the smallest, labelled as "fast freeze".
There seems to be small fan at the back it it, always running.
There is no option to turn on or off the fast freeze operation for this drawer.

Cheers.

 

[colinregan]

Hi

I have come across another interesting wesbite for finding and ordering spares, with a forum for some help.

They have lots of great articles as well, and this one about Frost Free Fridge Freezers was useful....
https://www.ukwhitegoods.co.uk/help...-a-fault-finding-on-frost-free-refrigeration/

In relation to my issue, they suggested replacing the Thermistor Sensor.....
https://shop.ukwhitegoods.co.uk/ser...ats/30014912-fridge-freezer-thermistor-sensor

No details on precisely where this locates, or how to fit it, but a useful comment....
"That is the thermistor used in it but there is no detail on where it is or how to get to it but, it's not a long cable and has to connect to the board so I'd guess in the fridge at the top/back somewhere."

So if anyone has any guidance on how to get into the surround of the unit, it would be appreciated.
The circuit board is fitted inside the centre top of the fridge, with a multipin connector to cables disappearing into the void above. This connector then fans out to three connections on the ciruit board.
Here is picture of the board fitted to its housing, showing the wires to the multipin connector.



Cheers, Colin.

 

[colinregan]

Hi,
So, anyone know how to open up the top of a fridge to get to behind the wiring ?
There is no sign of any screws.
Here are some pictures of insde.

 

[McrRed]

There's a YouTube video that shows you how to replace the sensor. Apparently it's buried in the wall of the fridge, halfway down the left hand side. Unfortunately this means cutting it out and then replacing it then sealing it all back up with foam or other insulation material.

We didn't want to do this for cosmetic reasons so we went for a workaround.

We got an on/off timer. Setting it to 30 minutes on, 30 minutes off didn't allow time for the compressor to engage so the fridge freezer slowly defrosted. 45on/15off seems perfect and fridge and freezer are now the right temp albeit every now and then the light doesn't come on!

Hope this helps someone.

 

[colinregan]

Hi McrRed,

Thanks for your comments and info about the on/off timer cycle.
This is what I have had to do now, and I've currently got a stable temp setup with 15min intervals for on/off.
I've also fitted temp sensors to the fridge and freezer sections so I can monitor them and can easily adjust the timer if necessary.

In terms of trying the fix the issue, I did purchase the thermistor mentioned above, but struggled to find its location.
I was advised that it could be in the back of the freezer section. I was able to get in there and find a thermistor.
It had a different connector type. I removed it and it seemed to be faulty, an open circuit, infinite resistance.
In testing with a multi-meter I was able to identify the wiring pins on the control circuit board. This helped identify a second thermistor circuit input on the control board. I suspect the 2nd being from within the fridge. The latter seemed to behave correctly, with a resistance of around 5Kohms, increasing with temperature of the fridge.

So I replaced the freezer thermistor, and checked all connections etc again.
I was being optimistic ! But there was no change in the behaviour of the fridge section.
It would go down to about -27C, with the fridge going to -6C. So maybe it was my control board faulty, but at £40 I wasn't prepared to try another one.
Also, I tried disconnecting both the sensor inputs to the control board, effectively making them infinite resistance.
Under this circumstance, the freezer sits at -18C, with the fridge at -2C.
I tried a few combinations of fixed resistors 10Kohm, 20Kohms, 50Kohms etc, getting different temperatures, but nothing was better.
So maybe the control board was working in some way !

I'm now running with the sensors disconnected, and a timer on the incoming power to turn the entire FridgeFreezer on/off every 15 mins.
I might change it to 30 mins cycles, or some other combination, particularly as we move into autumn and winter and the ambient temperatures change.

At least I've not dumped it !

Cheers.

 

[Kyle Hyslop]

Hello Colin,

I have exactly the same issue, did you find a fix or did the timer solution last?

Regards,

Kyle

 

[Harry Bloomfield]

No details on precisely where this locates, or how to fit it, but a useful comment....
"That is the thermistor used in it but there is no detail on where it is or how to get to it but, it's not a long cable and has to connect to the board so I'd guess in the fridge at the top/back somewhere."

If it uses a thermistor for temperature sensing, then your thermostat will be an electronic one and connected to the thermistor. If you can work out which are the thermistor wires, then you could check the resistance there, of the thermistor. A common value used for such applications is a thermistor which will have a resistance value of 10K or 10, 000 Ohms at 20C - but note there are other spec... The actual resistance of a thermistor varies with temperature, which is why they are used.

Other than that, you should completely empty both fridge and freezer, then leaving the doors open, give it at least 24 hours to defrost.

 

[mike_haben]

I have an Electra fridge-freezer with the same type of electronic thermostat, and the same symptom - fridge compartment temperature below freezing even with the thermostat dial turned down to 1. I've just tried the solution suggested above - empty it, let it defrost completely, and make sure there's nothing blocking any inlets/outlets. Being an engineer (and therefore convinced that I should be able to fix just about _anything_!) I went a step further and removed the panel at the back of the freezer compartment. In case it's of any interest/use to others, attached are a couple of photos of what lies behind it.

I unplugged and replugged each of the connectors, and poked a wire down the hole at the bottom of the radiator element thingy. Jury still out on whether that's made it work any better...

 

[Harry Bloomfield]

Rather than scrapping, and if part are not available, inaccessible to replace then one way to fix a fridge freezer with a single shared compressor, would be to cobble together a couple of thermistors, adjustable comparators and relays. Idea being to have one thermistor in each compartment, with each able to switch on the compressor if they detect being above the set temperature.

 

[mike_haben]

And... that seems to have fixed it! The connectors were surprisingly easy to unplug, so might have been just some oxidisation of a contact pin.