Correcting temp control on fridge/freezer

We have an AEG fridge/freezer combination with Santo 'fuzzy logic' temperature control. It has controls on the front for adjusting the fridge and freezer temperatures, with a digital readout giving the set and actual temperatures. I had reason to measure the fridge temperature recently, and found it much higher than indicated on the digital readout (I used both a mercury-in-glass thermometer, and a K-type thermocouple with electronic meter, and left them overnight to stabilise). With the set/actual control reading 3°C, in reality it was only getting to 7°C, too high for my liking. Turning the control to minimum (2°C), only brought the temperature down to 6°C, still a bit high (I would like 4°C). The problem seems to be with the electronics interpreting the signal from the temperature sensor, i.e. it sees 6°C as 2°C.

The freezer section suffers in the opposite direction: it's set to

-18°C but actually stabilises at -23°C. I'm not too concerned about this, because I can simply adjust the set point to a higher value, say

-15°C if I want it less cold, but I can't persuade the fridge to get any cooler.

Can I adjust something so that the internal and indicated temperatures are the same, or at least closer together? Where are the control electronics located, and how do I get into them? Can anyone advise?

(The fridge/freezer is located in a utility room, away from heat sources, and with plenty of air circulation around the back. The two compressors are not running flat out, but cut in and out as normal).

Reply to
Chris Hogg
Loading thread data ...

Just a thought, but fridges are tall boxes, and if left to stabilise I would expect quite a large temperature gradient, ie the top (where you keep the butter etc) being a fair bit warmer than the bottom.

Where did you put your sensor? Try near the bottom and see what you get.

I would also think that there is a fair bit of hysteresis (can't spell) so put the sensor in a lump of something (tomato?) to average out the variation and see what you get.

Reply to
Chewbacca

Could probably be fixed with a resistor, but you'd need to show us the circuit diagram.

NT

Reply to
meow2222

I wish....

Reply to
Chris Hogg

Thermometer and thermocouple were on top of the salad drawer, where the user handbook recommends test temps should be measured. T/C in free air, but thermometer in a cup of water. Both read almost exactly the same the following morning. But thanks for the thought.

Reply to
Chris Hogg

ok then, it can be done without it. You need to find the measuring device, I dont know if it'll be a thermistor or thermocouple, but...

If a thermistor, all one need do is add a little series resistance to shift it one way (perhaps 2-4% of its R) or a lot of parallel R to shift it the other way (maybe 25-50x R_thermistor).

If its a thermocouple you really will need to get to the circuit and trace at least the first part of it out.

NT

Reply to
meow2222

Try the forum on UKwhitegoods (google).

Might be a 'known problem'

cheers, Pete.

Reply to
Pete C ukdiy

OK, thanks, but I'll have to find my way into the works first! I was really hoping someone could tell me where I could find the trimmer pot that I assume exists for calibrating these devices. After all, an oven t/stat has an adjusting screw (probably a different mechanism, I know), as do older style fridge t/stats, so I presume this electronic thermostat has something broadly similar.

Reply to
Chris Hogg

Wasn't aware of it. Good suggestion. Thank you.

Reply to
Chris Hogg

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.