Engineering Mistake? Or Planned Failure? The Fridge.

Was it planned failure, or an engineering mistake? We routinely use copper pipe to carry water, so what would the harm be if the copper pipe was exposed to both air and water? Maybe one of the lowest customer ratings on a refrigerator isn't a good thing for building brand reputation.

I saw a local ad for a free refrigerator. She said it was new, but didn't work, so her husband took it home from work. The pictures on the ad looked good. But then I opened it up. Ugh. It was new how many years ago? She said the landlord was tired of seeing it in the back yard and it had to go. The thing was filthy from sitting outside with the doors open. But I figured I could clean it up and troubleshoot it.

After I got it home I looked up some reviews.

I regret doing business with Maytag – August 21, 2007
Do not buy this fridge – September 11, 2007
MAYTAG BLEW IT – October 4, 2007
MAYTAG ANTI-QUALITY – October 7, 2009
Worst Refrigerator I have EVER bought. – May 15, 2011
Ice 2O - Problems – April 27, 2007
Don\'t buy Maytag! – July 12, 2012
We were happy til now – April 30, 2008
Maytag MFI2568AES - Known control board failure – February 14, 2008
Worthless Junk – November 2, 2007
Ice Flapper Flapping – June 14, 2008

I should have read the reviews first. These reviews got one star, only because there wasn't a way to enter zero stars.

Well, at least I had a starting point to work from. The common failure complaints were the control board or compressor failing. So I decided to give it a shot and plug it in. The thing fired right up with no apparent problems, other than the high pressure line coming out of the compressor wasn't heating up. That meant there was either no refrigerant, or the compressor wasn't compressing.

Since this was a sealed system, I had to buy a tool to recover any remaining refrigerant. The Robinair 40288 line piercing valve did the job. So I attached the valve and evacuated the air out of the lines before piercing the copper. After piercing the copper, my pressure gauge went all the way up to . . . zero. Well, that explains why it wasn't getting cold. There was no refrigerant left.

I pressurized it with air to find the leak. I was all set to spray soapy water to find a leak, but the hissing noise told me I could find it easier than that. The copper line coming off the compressor was routed through the condensation catch pan under the fridge. I guess the hot tubing will help the water evaporate faster. But it'll also corrode the copper pipe. The pan was covered in green copper oxide.

When I cut and pulled the length of copper out, it broke at the leak. The wall thickness where it failed looked really thin.

1/4" OD copper tubing, thinned by corrosion

Here's a section that wasn't in the water. I cut it using a dremel so you could see the normal wall thickness.

1/4" OD copper tubing cross-section, cut with a dremel

I got out the micrometer and this good section was 0.2505" OD. The corroded section was 0.225" OD. That's a lot of thickness lost from corrosion. It appears that copper corrodes significantly when exposed to air, water, and heat all at once.

So I put in a section of 1/4" copper tubing, this time not routed through the water catch-pan. I verified there were no leaks by pressurizing it with 100 psi of air and using soapy water. Then I evacuated the air and let it sit under vacuum over night. Since the fridge may have lost some oil, I took a wild guess and added 5cc of PAG 46. Then I evacuated it again and filled it with about 0.142 kg R134a. At least that's what it's supposed to be. My cheap scale doesn't read down to grams. I stopped when it said -0.14 kg.

The fridge works now and has been running for a day. But the problem could have been avoided if the engineers had done some reliability testing on the new design, like measure how copper corrodes with air, water, heat, and time. Do some accelerated stress testing and calculate the lifetime based on the extreme use conditions.