Fridge controller

[skimask]

Can anyone give me the code and schematics for a full refrigerator controller. URGENT my food is spoiling! lol ok seriously now. has anyone seen a project such as this anywhere? we have a ge fridge that the controller keeps going out, and at 90 each, i'm going to try my hand at making my own. we have another fridge, so time isn't a problem. dont think it should be very difficult to make one that lets it cool, times a de frost cycle, and while i'm at it display temps etc on an lcd. just looking for suggestions before i start. like what would be an appropriate temp sensor for freezer? for fridge part? anyone know of an ice/frost detector/sensor? this should be a fun one for me. and i'll be sure to post code and schematics once i get it all done. these ge's are notorious for flaky controllers.

Do you happen to know what in particular keeps going out on them?

As far as the project goes...PIC (obviously ), DS18B20, well isolated PSU for the PIC/DS18B20, generic 16x2 LCD, opto-isolated relays for the compressor.

Frost detector? Shine an LED onto a piece of glass, photodetector on the other side. Glass frosts up, kills the light from the LED, bam, instant frost detector. I think. I've never tried it, but it sounds good to me.

And as far as I know (I just had my fridge worked on a couple months ago and I'm just going off what the guy told me), what a person needs to sense is the fridge temp, not the freezer temp.
The freezer gets as cold as it needs to be because the cold air gets there first, then it vents that cold air down into the fridge, usually somewhere around the front of the fridge, sometimes in the back. So, theoretically, the fridge could be 34, the freezer could be 33, or the freezer could be 0. Sometimes there's a damper that'll keep cold air from the freezer from falling into the fridge. Depends on the model I suppose.

[nomad]

The thermo stat/controller board goes out. the fridge will start getting warm, (inside coil frozen in a block of ice) then the de froster (heater) kicks in and floods the floor then the whole thing freezes up and never de frosts or cools until its unplugged for a bit. then it works fine for as much as 6 weeks, or as little as 2 days. basically the thermo stat is buggered but it's all one assembly (circuit board). the freezer temp is the one controlled by the main thermo, the fridge thermo controls a damper and fan to suck in air from the freezer. the damper and fan are near the top in the wall between the fridge and freezer compartments. it's a side by side unit. i'm going to try and locate a schematic so i can use all the sensors and controls already in place. since you mentioned a well regulated psu, it made me wonder if maybe this controller board isn't the problem, but is getting zapped or locked up from something else. think when i get home tues i'll scope the supply to the controller before i mess w it.

[nomad]

you wrote isolated, i read regulated. lol

[Archangel]

Hi Nomad,
Fixed a few reefers in my day ( the kind that keeps your food cold ) The defrost timer is a common problem, they get stuck on and then you have a proofer instead of a fridge.