Review of the Amish cooling unit

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Feb 1, 2005
Last month, our Dometic RM3862 refrigerator finally died.  The cooling unit failed and all the ammonia and some of the sodium chromate leaked out.  I had been corresponding with Paul Unmack, the inventor of the ARP control for RV refrigerators, to install one on our Dometic.  When he heard about the cooling unit failure, he arranged for me to get a special price on an Amish cooling unit from and he offered to install it at the same time he installed the ARP.  In return for the special price, Paul was to post a page on his web site, documenting the installation of the cooling unit and ARP control.

The cooling unit was ordered and arrived at our place on Nov. 11 and Paul arrived on Friday, Nov. 29.  Paul and his wife Mao immediately began removing the refrigerator to access the failed cooling unit.  In just a few days, the old unit was removed and the new Amish cooling unit installed.  The process is documented in detail here . They installed the ARP control at the same time.

After the cooling unit was installed and the refrigerator turned on, we were pleased to see how rapidly it began to cool.  As the graph on the above page shows, it cooled one gallon of water from 70?F to 40?F in about 12 hours.  The freezer was below 0?F for the first time in years.  It previously had stayed between about 10?F and 15?F.

We were impressed with the construction of the Amish cooling unit compared to the Dometic.  It appears to be made with heavier gauge tubing.  The unit came with a tube of mastic that was liberally applied to the evaporator tubes and a can of spray foam to seal the evaporator into the refrigerator.  There was also a roll of metal tape if needed for additional sealing.  The actual installation could easily be done in a day for someone with any experience but it does take two people to place the cooling unit into the refrigerator.  At Paul's request, I had constructed a 24"W x 24"D x 15"H platform to make the removal and replacement of the refrigerator easier.  Paul removed the doors before we pulled the box, which made it lighter and also easier to lay it down on the front face for working on the cooling unit.

I have the ARP unit with the optional data collection cable, but until we get back on the road, it isn't collecting any interesting data.  When we take the motorhome out for any reason this winter, I'll start the data collection to see how the boiler temperatures vary as we move around.  If I get any interesting results, I'll post them here.
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