What an amazing coincidence!

I just replaced the controls and sensors on my mid-range pricing electrolux/frigidaire side-by-side… it is a long story. I make candy as a hobby, and I have other friends who also enjoy my hobby. Also, I am “common law married” to a very skilled pastry chef here in Massachusetts, so the refrigerator is of central impotence in my life.

I want to point out that frigidaire/electrolux products are in fact designed by people who care too much, and that many of them went on to design the Vista operating system,which was later marketed as Windows 7.

But let us return to Frigidaire/Electroluxe.

It turns out that these firms had a long run of bad designs between 1996 and 2010. Many of these involved “economic engineering” – you know, of the “let’s ditch the crusty old farts and replace them with some young guys who understand the internet and social networking” variety”.

The new breed was very focused on the future.
However, this didn’t work out so well for the consumer, as ICQ turned into AIM, and AIM turned into facebook, and facebook turned into a popular place to avoid doing actual work.

By 1998, the average life span of certain brands of appliances started dropping, and by 2003 had dropped from ~2.7x down to about 1.3x, where x was the warranty period.

Of course, since that Edward Deming guy died, 1.3x isn’t what it used to be, so let’s pretend that it’s now a random number providing us with a working appliance for something between 30 days and -rarely- as much as 9 years.

We made it to 7 years before my refrigerator started making Darth Vader “breathing” sounds a few months ago. A few hours of googling revealed that almost any appliance attached to the firm of electrolux/frigidaire (they have about 30 names) seems to have dreadfully short lifespans… and in every case, repair was “non-economic”.

Being the chipper supporter of the american way that I am (I plan to vote Palin 2012 and hopefully she’ll replace the constitution with a modern EULA modeled after the very successful one used by Microsoft), I decided to fix the system the right way… by ripping out the control board.

The control board wasn’t broken, by the way – it’s just that bad software costs less than good software. The holidays were coming, and we had a lot of candy to make and pack for the gift shops.

Also, I am unemployed, so I must run our business by default. However, I had most of November to work on this a little at a time.

Refrigerators are not sophisticated. It wasn’t hard to locate the sensors – and replace them with solid state temp sensors, including drilling and epoxying new sensors spaced at 10 inches up the side of the fridge, as well as at various points in the freezer and fan compartments.

Let me be the first to say that I went overboard, using almost 24 temp sensors, 4 current sensors and two thermocouples. I won’t say what board I used, but my craptacular software lets me either write or read a string to the system from a PC.

Writing simply turns things on and off (compressor motor, vent controls, heater, etc). I left the fridge light and water/ice dispenser alone, apart from reading the temps and motor status.

I basically read a long string of ASCII hex that corresponds to each sensor with resolution equal to about 10 bits. Accuracy isn’t much to write home about, either.

Before I pulled the board, I recorded the values for 3 days. I made some mistakes in writing the software, but the fridge was basically empty (we have 3 of them, thanks to late 20th century economic models) at the time. Also, the electrolux/frigidaire had been spoiling milk for some months, so we were ready for the worst.

Did you know that milk often sits unrefrigerated on docks for hours at a time before it gets to your display case? You do now. It’s also common practice to turn off the refer portion of trucks for several hours and overnight to save fuel.

In fact, I had assumed that this was the cause of our milk going bad so frequently until I discovered that my fridge was randomly popping up to 54F for a few hours every three days.

BTW, my problem was ice buildup on sensors due to issues with the ice maker. The electolux/software didn’t take this into account, and was telling the fridge to both blow and not blow at the same time. Life on mars, as it were.

My housemate/life partner (let’s call him Klaus) is not happy at the fact that I have done this, as it took a great deal of time. Also, the fact that I re-purposed our Kitchen’s electronic picture frame to provide status information has annoyed him to no end, and as a result I did not find any fudge in my sock, only peanut brittle and a Sarah Palin calendar.

In the end, it was not cost effective, and we will likely buy a new unit. However, I am very happy at the results. I will say this:

1) Use relays for low duty cycle AC control, and solid state relays or zero-sensing Triacs for variably duty cycles.

2) It is as easy to wire 8 sensors as 1, if you use a multiplexor or use I2C sensors. Calibration is another story, because I needed to measure below 0C, so one must use dry-ice. Better to use pre-calibrated sensors. Calibration was the worst part of the project.

3) low cycle times with some temperature drift is better than continuous control. The compressors do not like to be manhandled, so you should try to control the fridge side with the fan and vanes.

4) I worried about drilling the insulation, who knows what this is made of?

5) Read a few articles on refrigeration before you do this. You can easily replace a thermostat, but if you want to be more sophisticated, you should understand the cycle.

6) MS C sharp is the new visual basic. It’s like C flavored VB.

My next project will hopefully be an automated fudge packing machine. It will be powered by an arduino, since I am curious about such things and often see them mentioned here.

The problem is that Klaus and I have so little time together – It is my desire that we can make each batch, and then put the slab into a machine that will cut the pieces and arrange them.

I hope to also have each piece wrapped in tissue, but my mechanical abilities are not so good.