Lamona HJA 6855

[Malcolm58]

I believe this is manufactured by Becko. It has become a freezer/freezer, ie it never cuts out which suggests it is a thermostat issue. The articles on Whitegoods are great and stopped me buyng a pcb which I was always doubtful was the cause. I can find the thermistor in the freezer (black two core wire) and when unplegged from the main PCB shows an decreasing resistance as temperature rises. There is another two core blue wire on the same part of PCB that disappears into the foam. I am assuming this is the fridge thermistor. Where is it located inside the fridge and how can it be changed.

[kwatt]

Sadly, they do not show those or the position of them on any of these units, you’ve got to try to find them on each one. But, they are usually buried in the insulation and need dug out.

K.

[Malcolm58]

I have bought both freezer sensor and air sensor. I have put the freezer sensor as near as possible to old sensor with a trailing lead out of freezer. Once I get to a stable temperature I disconnected the mains and measured resistance at circuit board of old sensor and on trailing lead of new sensor. They are within 10{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of each other and both change with raising or lowering temperature. I am assuming this is not the problem. The air temperature is more difficult to compare because I cant locate the sensor but the old one does have resistance wich varies as temperature varies. I am now thinking this could be a problem with the main circuit board. I don’t believe it is the contactor on the compressor because on initial power up the compressor runs for a few seconds then stops and after about 10 mins the compressor starts and operates well but won’t cut out. Do you have a circuit board attached are pictures of model label with serial number and main circuit board.

[kwatt]

I’d advise changing the fridge sensor first before you assume the board.

The board, if you need it, is this part:

http://shop.ukwhitegoods.co.uk/4360622900-fridge-freezer-control-module

It’s not expensive, as these things go but I’d still think it to be a sensor issue.

K.

[Malcolm58]

I guess I need to start cutting into the insulation to try find the sensor. I have just put an enquiry on parts finder which can be ignored now you have responded.

[Malcolm58]

Having excavated some of the foam it looks as though the wiring which is all tape wrapped goes towards the side of the fridge, which is where the door light switch is. Do you know whether the metal side will come off as this may expose the fridge sensor?

[kwatt]

No, it won’t, it wraps around.

It’s buried in the back, you need to follow the wiring.

The board only does what the sensors tell it to do.

K.

[Malcolm58]

I am still trying to fix this issue. I have fitted fridge air sensor as best I can. I cannont get to old one but have put replacement against plastic shell under the insulation. The only thing not replaced is the little circuit board in light unit. This seems just a dumb board to hold the potentiometer. Would it be possible for you to check resistance of a new one. I get 50 Ohm at Max setting and 47 kOhm at min setting. I presume this goes in series with the thermistor somewhere on the circuit board. I don’t know where to look next.

[Dom Hanbidge]

Hi Malcolm58 – Did you have any luck in sorting this problem? I have the same model with the same fault! – Looking for any pointers.

Dom

[Malcolm58]

Dom, I haven’t sorted it. I have changed everything except the little pot in the light. I checked both the thermistor resistances warming and cooling and they all seemed to behave correctly but I changed them anyway. I think I am resigned to having to buy a new fridge freezer. As a very temporary measure I have been running it with a time clock on the plug so I run it for a couple of hours then switch it off. Not ideal but stops the fridge freezing everything. I would not recommend trying to find the fridge air sensor or even trying to replace it. I can’t even find a way of fooling it into thinking it is cold enough to see if it will switch off.

[kwatt]

It will not be the small control PCB, loads of people (trade included) have changed that thinking it’d cure this issue and, it doesn’t.

It will, almost with 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} certainty, be the fridge thermistor that’s the problem so you need to find that, dig it out, replace it and refoam the cabinet where it came from. To find it, you need to follow the wires, there is no other way.

K.

[Malcolm58]

K I have changed the fridge thermistor. You cannot follow the wiresas to the thermistor as they go between the side panel and plastic case and the side doesn’t come off as you said in post 8. If I knew exactly where the old thermistor was I would cut a hole in the metal case with a multitool. I stuck the new thermistor to the side of the fridge internal plastic case as far in as I could get. Any decent design would have put the thermistor inside the fridge compartment under a plastic cover so it could be replaced, the freezer one is internal.

[kwatt]

Those sensors were never intended to be replaced, that is why they are like that.

Having to cut the backing off and get that back on etc is not fun at all but, it can be done.

K.

[Dom Hanbidge]

Thanks Malcolm

I have ordered both the freezer and fridge thermister. Will have to see if i can work out were they are. Does resistance of Fridge Air Sensor Increase or decrease with a reduction in temperature? Could add tempory resistors to circuit to test?
Also, am I right in thinking the PCB that these sensors connect oto is accessed from the rear of the unit? I have been behind the panel in the freezer section (and replaced the defrost heater as it looked burned out but wasn’t), but all items just wire back to terminal block, or cables pass through rear housing.

By the way, the timer is a clever shout, may just have to use that to get me through xmas without the wife killing me!

[Dom Hanbidge]

Hi Malcom

I received both sensors yesterday and set about changing the fridge one first.
What a pain to find, but I recon (knowing where abouts it is) you could change it over in under an hour (including removing fridge/freezer and refitting it in the cabinet)
its on the back of the unit behind the grill.
You need to undo the 4 hex head screws and tilt it to the side then put one of them back in to hold the grill in place to stop it damaging the connections on the bottom right.
The sensor is in the centre of the back 10” down from the top of the unit (behind the 3rd little circular bump on mine)
it is about 2 1/2” deep, pressed up against the metal back plate. The cable feed to it from the left, so you will need to follow that way to give you a bit of slack.
Early days yet, but all seems to be working fine (freezer still freezing and fridge cold but not freezing)
hope you get yours sorted.

Dom

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