Hoover HNMF 2805A L80 – frozen fridge problem!

[ChilliWilli]

Dear UK Whitegoods,
Firstly, wow, what a great and useful forum. I had no idea that this existed and I have learnt loads already 😀

Secondly, I can’t believe that on such a big forum which includes a refrigeration help and support area, no one has bagged the username chilliwilli! Maybe it’s my childish nature?! 😳

Anyway, please can I have some help and advice?

I have a hoover HNMF 2805A L80, which I think is the same as HCF5190, but the first number definitely came off the fridge. The fridge keeps freezing up and the compressor is on all the time, unless I a) turn it off at the wall, b) turn it down to 0 on the dial, c) or turn it up to quick freeze briefly then to somewhere between 1-4. Option c) only work for a few minutes before it reverts back to its “constantly on” behaviour.

The freezer is at -18C (OK to me) and the metal drip strip from the freezer section at the rear is damp and warm. I think this means it is behaving as it should, that is it is going through its defrost cycle.

I have checked the fridge drip channel and pipe are clear and I have also defrosted the fridge-freezer several times to no avail.

Is this a thermostat problem or circuit board problem? Can I fix it myself or is it a no-hoper?

Any advice would be appreciated.
Many thanks,
Willi

Other useful numbers if needed
TYPE PF28
3400056105488715

[helo_75]

mmmm

here goes

there is a foamed in thermistor, which is usually the culprit to be fair

its not a nice job, its quite involved and messy

a pcb usually cures it

how are u with a multimeter?

[ChilliWilli]

Re: Hoover HNMF 2805A L80 – frozen fridge problem!

helo_75,

Thanks for the reply. I am fairly competent with most DIY jobs and can take most things apart and put back together again without any hassle. Regarding use of a multimeter, as long as I know what I am looking for I can use one and diagnose problems with one. I have a fairly decent one too which will test mains rated appliances (700VAC, 10A). If you can point me in the right direction that would be great.

Some recent observations: – I did find on the rear of the fridge-freezer, roughly at the height of the middle of the fridge section, a block of ice that was forming on the outside, where the plastic insulation and the silver/aluminium coloured plastic cladding of the outside of the fridge meet. That is down one long edge of the FF. It was not touching the radiating bars. I hope that makes sense.

Could it be that the temperature sensor has been inadvertently been moved out of position by being expanded out of its original location through the ice formation? Just an idea.

Thanks again for checking my post out.
Willi.

[ChilliWilli]

Re: Hoover HNMF 2805A L80 – frozen fridge problem!

Dear UKWHITEGOODS,

I was brave this morning and decided to investigate the PCB and found something interesting! I spotted some scorch marks on the outside of the PCB casing, ignored the “void warranty if opened” message on the plastic cover and found a couple of black heat marks that were exactly opposite some surface mounted resitors (104 ohms). These are part of the circuit that feed into the temerature sensor.

The resistance accross them still adds to there printed value and the circuit continues to conduct, so as far as I can tell the PCB is still intact; it just appears to have got a little hot at some time.

Is there anyway I can test the temperature sensor to see if this has been damaged? Is this a PCB issue or a temerature sensor issue, or both?And is there anyway that I can try a slution out before paying for a brand new PCB only to find out it was the sensor?

Thanks again all.
Willi

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[helo_75]

if u use your meter its as easy as putting the probes on the wires, and warming the back of the fridge up with a hairdryer, and see if the resistance changes

pcbs rareley cure that problem

as for the ice outside the appliance, thats more likeley just because its over running, which would suggest either the pcb is ignoring the sensor, or the sensor just isnt working

sorry for my delay in posting, i have so much to do lol

good luck

[ChilliWilli]

Re: Hoover HNMF 2805A L80 – frozen fridge problem!

helo_75, et al,

You were spot on with your diagnosis technique! I hooked up my multimeter to the ends of the defrost sensor and could only get one reading of varing resistance with temperature.

I measured at the terminals that enter the PCB. There are two sets of 2 wires for this FF. See below for picture.

One pair in blue and one pair in white. I could only get a reading from the blue pair. So I guess my FF gets the freezer signal, but not the normal defrost signal and does not go through its proper defrost cycle? I tried cooling the sensor down to freezing with some ice blocks but nothing on the multimeter. Is this a good enough test?

So if this is a sucessful diagnosis of the problem….. If this sensor is all foamed in, can I buy a new sensor, snip out the old one, splice in a new one in the freezer section (where it normally lives), and use something like a hot glue gun to make the splice water/ice proof to lessen the hassel of replacing the faulty sensor? Maybe someone can/needs to PM me and discuss this offline to preserve professionality?

Cheers all,

Willi

[Rbz5416]

Re: Hoover HNMF 2805A L80 – frozen fridge problem!

Did you ever sort this as mine is doing exactly the same?

[Rbz5416]

Re: Hoover HNMF 2805A L80 – frozen fridge problem!

OK, perhaps someone else would like to chip in as it looks like the OP isn’t around.

Mine’s getting worse & actually freezing stuff in the fridge so I’ve got to act. Two more symptoms from mine:

When set to the zero position, the compressor &/or fan continues to run. All that happens is the fridge light goes off.

When set to Super (max) the compressor & light sometimes briefly switch off & on again. If left in this position this randomly repeats every 10-20 seconds. Backing down from this position, the compressor stops but then immediately starts again.

My guess is that this behaviour must be the controller module as a duff sensor shouldn’t cause the compressor to run when set to zero. So my choices are to buy a controller PCB & hope for the best or pay Hoover their £129 fixed repair fee & let them sort it. Controller seems to be £60 from the only source I’ve found so far so I’d be gambling on maybe saving £70.

So does anyone have a resource to show me how to change the controller or have an alternative plan? I’m in Colchester.

[Rbz5416]

Re: Hoover HNMF 2805A L80 – frozen fridge problem!

Well just in case it helps anyone else:

I pulled it down again to check the fridge temperature sensor, which it turns out is a thermistor. That’s the white sleeved cable with the two pin connector. With the fridge pretty cold & it disconnected from the PCB it was reading 6.8k?. Just with the door off, it started dropping. Went down a couple of hundred ? in about a minute so this seems like correct behaviour.

On that basis I bit the bullet & ordered a controller PCB & that seems to have done the job. Total cost including RMSD was under £50. 😀

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