Check out this little General Electric Monitor Top DR-1. It was given to me after a friend acquired it and found it nonworking.

The DR series was the original Monitor Top design produced from 1927 to 1932. They have the open coil condenser on top and intricate clockwork controls. The most collectible, but also the oldest and least refined design - these are often used as storage cabinets and interior decor once the cooling system becomes nonfunctional.

I want to see if this one can be brought back to life so I did some troubleshooting and documented the findings in videos.

Part 1:



Part 2:



Sincerely,
David

Thanks Jon!  They definitely put a huge amount of engineering effort into these units. The DR's are especially fascinating because of their being the "first" version, and the "overall uniqueness" they possess. 

This model was introduced just one year later than the Frigidaire M52 belt-drive I'm also working on. It's so clearly a massive leap in a new direction that it's no wonder they over-engineered it so much. Everybody is afraid for their new design to be perceived as a failure due to small problems that turn into big headaches.

Hi Bud. That's a tough question. The GE Monitor Top fridges generally have a huge amount of oil in them.  There was still pressure in this system and no signs of large oil leaks. So I didn't see a need to add oil.

As for other systems, the GE Combination has a manual which shows the total oil charge. The systems with flooded evaporators such as the Philco, GE Flat-Top, and others with the evaporator that has a header built into it - those have to carry an extra large oil charge and the compressors were designed to operate with a widely variable oil level in the compressor. This is because widely variable amounts of oil are trapped in the system at any given time.

This is why retrofitting a modern compressor to these is very tricky. These compressors come with a minimum of oil in them and depend on it returning as fast as it leaves. They fail when the system collects oil in the evaporator.

As for knowing how much is too much - if the oil level gets up to the rotating parts of the compressor or motor, it would cause a huge amount of drag. The motor would overheat for sure. My uncle's friend told me this story. Somebody heard the compressor making a rattle and assumed it was low on oil. They bought one or two automotive oil charge cans (back when they sold R12 for $0.75 per can) and put it in the system. This caused the compressor to draw about 75% more power than it was supposed to. It also ran fire-hot and tripped the overload after 10 or 15 minutes.  I don't know how much oil is in those cans or what grade it is. But it was too much and the compressor got really hot.

I know most older compressors are designed for a large oil charge. The GE Combination wall mount had if I remember 800CC (about one quart) listed oil charge. I added an extra 4 ounces of oil to it since I had replaced the condenser coil, dryer, and blown a bunch of oil out of the rest of the system.  That was an "educated WAG" if you know what that means. :)

Manufacturer's literature is the best way to know the original oil charge but even that is not always easy to interpret. Cutting open old compressors and looking for telltale signs of where the oil level was, or studying the design and seeing what the highest level that would not cause problems would be, has been valuable as well.

I have had to make the videos private for the time being due to YouTube issues. The DR1 is still working fine.

Hi Keith!  The Monitor Top design was very good, for serviceability as well as efficiency. I like your idea of using a MT cooling unit on a modern cabinet as a replacement cooling unit!  That would be interesting to see for sure.

Interestingly, many other manufacturers had unitized, removable cooling systems which attached to the top of cabinets. Westinghouse had one which could slide out to the front, with a round wood post containing the lines and passing through the cabinet top.  The top had a compartment concealing the unit, so it didn't look like a GE. But there was some shared ideology.

Eddie - thanks for the compliment on my repairs. I am not that good - I just learn fast and manage to catch mistakes before they become bad LOL! 

Yeah I noticed how the commercial machines are similar to how the antiques were. They sell cheap shit to the homeowner but the commercial guy can still buy a quality product meant to be serviced. 

Keith, you got me thinking now - will have to look at the next ice merchandiser and see how the evaporator is done inside! 

Still working!