Candy Frost Free Fridge Freezing up totally

[engineer11]

Dear Sir, My elderly parents have a Candy frost-free fridge, and it started freezing up solid in the top part, freezing the milk solid etc. The milk was totally rock solid through and sticking out of the top, so it was really cold in there. They are getting a bit fed up of this now after a few months of me messing with it to try to fix it on-and-off. Before I go on below, I am an electronics engineer, and I can solder etc, and I rework SMD components for a living. I took out the PCB, changed the capacitors, and the relay, checked all the other components over, resoldered all of it, and refitted it, and it appeared to start working OK. However it has started freezing solid again after two months. Gradually getting colder and colder as if the timing intervals were out or somehing silly. I don't think that it is the PCB at fault to be honest at the moment, as it has been working fine again. I took the panel off inside on the freezer part, and there is a fan, heater, and the heat exchanger panel. Also there is a white box that is supposed to switch over when it is cold, as I got the data sheet from the US, and they told me that this is working OK after taking measurements when warm/cold. I have used a meter and observed this "little white box" is switching over OK. when the fridge gets cold at the bottom, and at a higher temp. it switches over again. (defrost cycle?) The 240V fan is working OK, and the heater measures low resistance showing that this is OK too. I have measured the thermistor input going into the control PCB, and this seems to be changing with temperature from low to high as in 5 to 10K or somewhere around this lower end, but I can't remember exactly as it was a while ago, but it was correct according to figures that I have seen before. I don't particularly want to waste my money on a PCB, when it could be something else though. Going on what I have found so far it seems hard to pinpoint without some parts to swap out, or a "flight kit" as they say! Have you got any ideas what it could be before I take a gamble and order a new PCB? BTW they switched it off, and now it is OK, but after a while it seems to "forget" the settings again, and freeze up again solid! So as it is OK, could the PCB's EEPROM or PIC, whatever it is be going faulty every once in a while? If it is OK, this proves that all the sensors are OK, but when it throws a wobbly it will gradually begin to freeze solid over several days. The heater, fan and the little "white box" switch are all working as I said before, tested them a few times. Mystery this one is. Any ideas anyone? Maybe I'll just get a part-ex PCB from eBay and take a chance if all else fails? Any input would be valuable please though. Thanks, Mark Lawton

[engineer11]

Sorry about the no paragraphs, I cut and pasted this in OK, but the formatting has got lost.

Mark lawton

[spimps]

Can you supply model no please ? might be better able help then.

[mikeref]

Sorry about the no paragraphs, I cut and pasted this in OK, but the formatting has got lost.

Mark lawton

Yeah, domestic fridges. Pcb's is are quite a problem to sort out. Is it the pcb or the probes. I would replace the pcb but this temperature variation could be caused by the probe feeding wrong info to the pcb. When commercial fridges do this, i replace both to avoid callbacks.. mike.

[marsh1981]

Hi, if you have not already solved the problem on this candy f/f. I can confirm that on 99% of these that I have come across the cause is the pcb. The fridge probe is foamed into the lining on these and if they fail (very unlikely) you will need to remove some foam from the rear of appliance to gain access. Used to work for gias (candy/hoover repair agent) 5yrs ago and went through a period of replacing a few of these pcb's. Hope you get it sorted.

[tb637]

Hi, this is not the p.c.b. the candy f/f has a sensor for the fridge inside the insulation at the back and top of the cabinet,(about 6" from top left corner and about 6" down)
You have to dig it out carefully and change the head of the sensor by stripping back and joining the two wires together.
After the repair you have to fill the insulation back in with a can of expanding foam. Not an easy job

[engineer11]

I am about to go for broke and order a new PCB for this candy fridge.

I have measured the heater, and the little switch box by this on the internal heat exchanger fins at the back inside the fridge, and they are OK. Heater is low ohms, and the defrost switch changes over when cold and then goes open when it is warm.

Thermistor in the top of the fridge changes resistance when it is cold.

I think it was 10K when cold, but a lot lower when warm.

Fan is running OK as well.

What else can it be?

I have resoldered the components on the PCB, changed the capacitors and the relay as well (I am an electronics engineer). The two triacs are OK as well, as I removed them and replaced them, although the gates were switching OK, but to be sure.

There isn't a lot left on the PCB to test I would think.

I really don't get this problem, unless the PIC chip (EEPROM) on the PCB is going flaky, there is simply nothing else left to test.

The fridge works for a week, and then starts to suddenly freeze up sometimes, and other times goes on working OK.

Once it worked OK for two months!

If an engineer came out, he would need a "flight kit", and swap out a load of bits, as this is would be random guesswork for most I would think.

Replace the PCB and see what happens, then the thermistor, then the defrost switch, then the heater etc.

Obviously I want to nail this problem on the first hit.

I haven't got the model number, but the PCB it takes is a CANDY CPCA240.

There is one on eBay item 130264647676

I emailed them a few times, and they don't seem to want to tell me a lot about these, especially as I do know electronics. I think that they only want to sell me a PCB.

They do repairs on the PCB for a lower fee, but if this is intermittent, then they could miss the fault easily.

I am getting the model number now.

Maybe it will pay me to start with the PCB and thermistor.

I will be back on here before I do anything, so I will get the model number, and await some more advice.

The fridge is 7-8 years old BTW.

Thanks,

Mark Lawton

[engineer11]

The model is CPCA240FFK, and not many people seem to have heard of this model.

The PCB is model 41012152 on the label which is on the white casing.

It has two LED's and "super freeze" only comes on when the setting dial is put on full, which indicates that this part of it is working OK.

If you put it on just 1, then eventually the milk freezes up.

I measured the thermistor, and it was about 5.2K when the milk had frozen.

I take it that I was reading the thermistor, as the other wires are either open or closed for the heater, and the defrost switch, or they have 240V AC on them for the supply, and some go to the interior light.

There is a 3rd black wire from what may be the thermistor, and this goes to a connector with three wires on it, but does not appear to measure between the 5.2K wires at all.

I heated the upper left corner with a hair dryer, and the value eventually dropped to 3.3K, but I did not heat it up a lot, and no doubt the heat did not penetrate that far into the casing to change it a lot.

I am using a travel fridge at the moment for the milk etc. and the freezer as normal.

The heater measures nearly a short circuit, and the fan is working OK, as I have checked these today on 6/11/10.

If anyone has any advice, then I'll take it up before wasting money on stuff I don't need.

For now I have put it back on, and I am getting a thermometer to monitor the temp in the top of it.

Hopoe someone can help throw some light on this, as they are so simple in principle, yet hard to pinpoint when the prooblem does not always happen.

BTW the seals and doors are fine, and it has worked in the same place trouble free for seven years.

It is in a cool verandah, next to a garage, where it does get cold, but is never a problem.

Thanks,

Mark Lawton

[sedgy]

eneneer 11, CHILL-OUT,
it can be a big problem with elderly pairents , having a problem with a fridge, or any other domestic gadget, but come on now if its that much of a problem , buy them a new one and take the problem one home and work on it, I will tell you I got jittery reading your letters , I hope your pairents where not subject to the same pressure, from you , they dont need it, life can be a bitch but dont go on about it but I still hope you get it sorted , sedgy

[engineer11]

eneneer 11, CHILL-OUT,
it can be a big problem with elderly pairents , having a problem with a fridge, or any other domestic gadget, but come on now if its that much of a problem , buy them a new one and take the problem one home and work on it, I will tell you I got jittery reading your letters , I hope your pairents where not subject to the same pressure, from you , they dont need it, life can be a bitch but dont go on about it but I still hope you get it sorted , sedgy

They can't afford another one.

Anyway, people like you can get lost!

No !jittery" here, my dad just wants it sorted cheaply, without being ripped off by the likes of you!

Get it!

Where do people like you come from...

Sheesh!

[engineer11]

My dad does not want me to buy them a new one, as he can see clearly like me that if I have the patience and time to wait, then a solution will come our way.

However people like you are the last ones I would take any notice of!

[mikeref]

My dad does not want me to buy them a new one, as he can see clearly like me that if I have the patience and time to wait, then a solution will come our way.

However people like you are the last ones I would take any notice of!

I doubt anyone would bother to help you with non constructive replies like this. The members of R.E. give their time for free and we all should respect that... I was going to ask/ and now will do so, have you followed up on TB 637,s post?

[engineer11]

I'll have a look at that thanks.

About the response...

I joined here to get free help not sarcasm, as the idea of this is to fix stuff cheaply.

Neither my parents or I wand or need to buy another fridge. A new one as good is over £300 now, which to them and us is a lot of money, as we are not "easy come easy go" people who change their car because it has a scratch on it for example!

If thy buy another one and I fix this what will I do with it?

Second hand stuff does not sell anyway. OK maybe we could buy a second-hand one then.

They are using a portable one for the everyday stuff.

This can and will be repaired cheaply, even free!

My next experiment will be to get a thermistor and tack it onto the PCB, and see if this works. I can get the right kind.

If not then I will buy a new PCB.

Just don't want to waste money, that's all.

Some people on here have been great, but others not so great.

I was even going to help on other posts, where I am more proficient.

OK enough said now, so that is that.

[sedgy]

hi henginear one ,one , I was trying to give you an idea, on the right way to go, your dads fridge is 7-8 years old its possibly on its last legs, your idea of fixing it for nothing is pie in the sky. and as for ME ripping YOU off I dont work , when I did work I would fix domestics in my spair time and not charge, lets face it if you cannot fix a domestic, what can you do?
by the way philately will get you no-where. sedgy,

[engineer11]

Well I have fixed it for free now!

It was the thermistor after all!

I got one from out of an old controller unit hat I had nearby and tacked it onto the back of the fridge inside and ran a temporary cable to the controller PCB. It is a 10K NTC.

Yippeee!

Freeee!

I will now fit it in the back by digging out the insulation and replace the original when I get chance.

I didn't ask for any sarcasm, as I expect appliances to last 25 years generally!

My washing machine was made in 1983, and I have repaired it 3 times for just the cost of a cheap pub meal!

One place of employment ask how old your washing machine is, and when you say "25 years", they say "you can start on Monday"!

[tb637]

I take it that you didn't bother to read my post on how to solve this problem or you knew better. When i ask questions on other forums and i get an answer i thank them for their response

[engineer11]

Couldn't find it actually, if you give me the URL pasted in, then I'll find it, same with the other mention higer up, never found that either, sorry

This forum isn't that searcheable at the moment I have found.

[engineer11]

If you meant the one about the sensor on here...

I had conflicting views that it was the PCB, sensor of both, so I eliminated it by doing an experiment.

A local engineer also told my dad that frost-free fridges were nothing but trouble, as there is som much more to go wrong.

Yes I read the psot about the sensor, and digging it our to replace it.

Still running with one inside taped to the back at the moment.

Thanks.

[tonto33]

send your pcb of to http://www.qer.biz/ and they will check it for you see if board is faulty

[cameraman]

FOR FUTURE REFERENCE, THE READINGS FOR THE FOAMED IN SENSOR ARE AS FOLLOWS
-30'C @ 47 Kohms
-20'C @ 26 Kohms
-10'C @ 15 Kohms
0'C @ 9 kohms
5'C @ 7.7 kohms
10'C @ 5.5 kohms
20'C @ 3.5 kohms

SUPPLIED BY GIAS TECH DEPT
Also, I wouldn't just change the head of the sensor but the head and lead complete as adding a connector can alter the resistance reading. We experianced a 15% failure rate on the sensors in the late 1990's and as far as I know the sensor was still in use until at least last year.

[engineer11]

Hi there folks,

The PCB repair is too expensive at QER, so I serviced the PCB myself just to be sure I had nailed the problem, and now changed the sensor as well.

Used a soldered joint with heat shrink sleeving to connect it, and used heat-sink paste for transfer of heat, and it is all glued up now foiled and taped over etc.

I managed to get a Gias guide on where the sensor is located, and how to change it.

All working OK now and above freezing in the top, and no solid ice cream in the freezer when it is supposed to be soft-scoop! lol

Thanks for the advice then folks, I'll know how to deal with these in future.

Just a point... if it had not been freezing up when the motor was running, then obviously this would need re-gassing, as we once had a fridge that ran and ran, but just got hot at the back, and there was a leak in the tube at the back, as there was no gas in there.

I don't suppose they are worth regassing then in that case, as I have always bought a new one if the gas has leaked out, as it isn't cost effective, and a bit specialised on something worth about £250.00.

Maybe on the big £500.00 and above fridges then they are worth it at a guess.

I don't know about re-gassing, and how cost-effective it is, other than using a cylinder with a dial gauge to top up my car's air-con once avery 3 years or so!