Very helpful.

[Ret.]

Our 4 yr old Hotpoint frost-free freezer started playing up recently. The 'Temp too high' light came on - and ice cream in the top drawer was semi melted. Turned the temperature control down and the light went out

- but ice cream was still not as 'solid' as it should be.

Was on the point of calling out an engineer when I read an earlier post on a similar problem. Someone pointed out that even though there is no visible 'frost' inside the cabinet - the evaporator, hidden behind the fan 'trunking', can become iced up and reduce the cooling efficiency.

So we did a 'de-frost' - and were surprised at the amount of water that came out.

Turned the freezer back on - and it's working perfectly again. So thanks to uk.d-i-y and contributors for saving me at the least a call-out charge!

[Ret.]

Hmmm.. Having done a bit more Googling on the subject, it appears that I may not be out of the woods yet - and if the evaporator is icing up, then that could be a symptom of a failed sensor or defrost timer...

I'll just have to wait and see what happens.

[Andy Wade]

... or the defrost heater itself - a common fault.

[Onetap]

I had a similar problem with a frost-free freezer recently. The refrigerant system seemed to be working, though not shifting the heat. I got an 'engineer' through Domestic & General; he seemingly knew nothing more than I did and levered the plastic trim off the back (breaking it) before leaving without fixing it , saying he'd consult a colleague and ring back.

He didn't ring back. Since it would be scrap if not fixed, I set about it and after an hour of gentle prodding at the trim, got access to the PCB and sensor connections through the front (NB there is no access through the back). The two thermistors had very different resistances. I repleaced one, with a manufacturers kit (=A330! For a NTC thermistor!!) and it went.

The internet recommendation seems to be to avoid frost free appliances.

I've had dealings with many thermistors as sensors on BMS installations, probably 1,000+ on one site, sensing from 4 to 100 degC approximately. I do not recall that they went ever wrong, but they seem to be a source of constant failures on domestic freezers and fridges, which are then scrapped because the "Engineer" can't replace them or his labour charges make the replacement of a =A330 thermistor uneconomic. If the thermistors fail so frequently, surely the encapsulation must be defective? There's nothing else to go wrong, SFAIK.

Or is this engineered-in failure to ensure a constant demand for replacements?

[Ret.]

Yes. One wonders...

The 'trunking' panel at the inside rear of the freezer appears to be fixed in place with just four screws - two at the top and two at the bottom. I did not attempt to remove it for the de-frost, but if the unit starts playing up again I will do so and see what I can determine!

[DerbyBoy]

... or the defrost heater itself - a common fault.

[fred]

In article , Ret. writes

Whilst it is ice free, now might be the time to remove the panel to see how it goes together.

In a similar spot with a Bosch frost free fridge freezer the amount of ice stopped the evaporator cover coming off and the cover staying on inhibited the defrosting. Hours of gentle heat from a distance with a fan heater on low sorted it out (beware excessive heat and internal panels melting).

Sounds like you have done your research, bear in mind that frost frees need air circulation to work properly and not ice up so try to avoid over filling the drawers/compartments.

[The Other Mike]

Unless you let it defrost for 24 hours or more in a warm room then you will need to intervene again, maybe in a few weeks, sometimes a couple of months.

Be aware that if it is iced up then the plastic will be frozen across a large area to the evaporator fins. You need to warm the area with a hair dryer for a good 10 minutes or more, moving quickly across the surface to ensure the plastic doesn't distort. Once that is done you can remove the panel and see the mess behind - usually a huge block of ice encasing the evaporator.

My advice is to buy a Hotpoint cooker, wire it up, and keep the ice cream in the oven compartment - make sure the temperature is set to max. It will do a better job at keeping the ice cream frozen than any of their freezer range.

[OG]

Not sure if it was my post - certainly I have posted about FF.

We tried a couple of 'defrosts' which made a bit of a difference for a while, but in the end it was only when we left ours off for 48 hours that it made a permanent difference.

It was only 48 hours because we were away for a weekend; 36 hours would probably have been enough.

[Weatherlawyer]

Doesn't that tend to be counter-productive in a society not locked into defective management?

[Steve Walker]

I wonder whether it is just poor specification. With a previous employer we had repeated failures of combined humidity and temperature sensors in bakery coolers - it turned out that the data sheet quoted a useable temperature range, but didn't say that to achieve the lower end of it, a low temperature version (with L appended to the part number) was required, as the normal version's humidity sensor couldn't take the lower temperatures.

We also had ongoing problems with infra-red flammable gas sensors in printworks - in this case the gases passing through were checked by comparison of absorbsion of IR by the gases against a that of a clean sample. This involved pulsing the IR sources (two non-replaceable filament lamps) 3 times a second and the designers/manufacturers hadn't considered the bulb life when repeatedly switched! The units were failing after 3 months and being replaced repeatedly under the 3 year warranty. They eventually solved the problem by ramping the voltages up and down.

SteveW

[Onetap]

I'd think it probably is, I looked at a thermistor catalogue and you can get specials for low temperature with different encapsulation.

BMS humidity sensors used to be unreliable, they aquired a big error if exposed to very high humidity. Later versions were much more reliable. Thermistors were generally fairly bullet-proof, IIRC.

[Ret.]

LOL! Oh dear...

[Ret.]

OK. Only time will tell...