Built-in Frigidaire system from 1926, repair for 100th year anniversary!

[turbokinetic]

Got a project to share! Thanks to fellow Monitor Top forum member Kevin Jones; I have been entrusted with repairs to this amazingly well-preserved Frigidaire cooling system. This is original to a home constructed in 1926 which is having some repairs done in celebration of turning 100 years old.

The late 20's was a transitional period from the icebox era to the electric refrigeration era. The kitchen was constructed with a built-in icebox as were many higher-end homes of the era. In this case, they went the extra mile and installed a Frigidaire electric cooling system for the icebox. I will share some pictures below, of the box and of the condensing unit in its place in the basement. This setup was bought and installed with electric refrigeration - the cabinet and cooling system were installed during construction of the home.

We talked on the phone about the status of the system. I sometimes have difficulty with phone conversations, so there may be some corrections later on. But the unit was in service until about 1970, at which time it began operating continuously without maintaining temperature. Troubleshooting was done and it was discovered that the compressor discharge valves were bad. The owner was able to get a new-old-stock part, but it turned out to be incorrect. The system was turned off and preserved at that point. It had been sitting as a static display from 1970 until last year. During house repair work, workers accidentally turned on the power to the condensing unit. The motor fired up and the compressor started, but the compressor shaft seal failed immediately. There was an SO2 release in the basement, requiring ventilation of the house. Power was isolated and the compressor service valves closed.

After discussing the possibility of repairs, the plan was to send the working parts here for rebuilding. I sent detailed decommissioning instructions. The evaporator and condensing unit had their service valves closed and lines capped. The parts were carefully crated by an industrial equipment transportation specialist and sent here for rebuilding.

Below are some pictures of the unit and pages from the Frigidaire manual associated with these units. Below the still pictures is a YouTube video link of opening the crate and doing some basic assessments of the parts.

Built-in cabinet. Based on an icebox design but it was installed with the Frigidaire system from day one.


The evaporator in its compartment.


Evaporator before repairing.



Page in manual for evaporators.


Specification for the evaporator.


The model G condensing unit.




Artists rendering from the manual.




This system represents the competition to GE's early Monitor Top. This was being installed while GE was marketing the mighty OC-2 machines. You can see why a "one piece" appliance such as the Monitor Top would have quickly taken over from such complex systems as this. It isn't that the Monitor Top was less complex - simply that it was all in one place, miniaturized, sealed, and didn't need any specialist installation nor the level of maintenance the open-drive systems do. This is one of the reasons there are MANY more Monitor Tops surviving today as opposed to remote unit open drives. Both of them are very important pieces of history which deserve to be preserved, but there are fewer of the early open-drives out there to preserve. That has led to a lack of knowledge on them and they are at risk of being lost. I hope you see my concern and share this thread and the video to help keep the interest up!

Video:
Click this link to open YouTube video!

More videos are posted and I will try to get them shared here as well.

Sincerely,
David

 

[turbokinetic]

As for the Frigidaire system, I made quite a bit of progress in the past two days. The video ended up over an hour after editing, so I broke it down into two parts.

This project has two somewhat-opposing requirements. It is to be as original as possible, but it also has to be very reliable since it has been shipped thousands of miles here for overhaul. There would be a very high cost in transportation if there are near-term failures. To help accomplish both of these goals, I have taken advantage of Frigidaire's "evolutionary, not revolutionary" engineering. Their initial open-drive compressor was introduced in the early 20's and produced into the late 30's and possibly beyond in commercial applications. These were refined through the years into an extremely reliable unit. The later ones really are good even by today's industrial standards for equipment used in an industrial setting (not consumer grade products.) One of the major improvements was the eccentric shaft lubrication system and thrust bearing setup for the shaft. As with all machinery, lubrication is the life of the machine, and improvement to the lubrication system is always a good thing.

Both the early and final designs use oil throw from the eccentric to lubricate the compressor. The early design had one small hole for oil to find its way from the eccentric to the shaft seal and bearing area. This hole was actually in a raised area where oil will be actively funneled away from the hole. The final design included two large oil cups to catch the oil and deliver it right to the bearings and seal area. The following capture shows the early and late designs. You can see why the later ones are a better idea. And, due to GM's evolutionary design, the casting is interchangeable and does not require replacing the whole compressor. The eccentric, pistons, cylinder barrel and all other parts are original.



The next area of concern is the mechanical shaft seal. This technology has been changed over the years. The opearating principle is to provide an interface between the rotating parts and the stationary parts, which allows rotation but does not allow fluids to pass. The interface between the moving parts is between two precisely fitting parts with a very small gap. The gap is so small that an oil film trapped in the gap will fill the gap and prevent passing of fluids. The most critical part of this design is that the stationary and rotating faces are perfectly flat, and never separate from one another during operation. For that reason, the seal system must be able to move axially without opening up the seal faces, in the event the shaft slides in and out while operating or in standby. This can happen due to crankcase pressure inside the compressor. For that reason, setting the thrust clearance on the compressor shaft is critical. It needs as little as possible, without binding. The seal assembly has a strong spring which holds the parts in contact with one another. The better the shaft thrust clearance, the less this spring must move and the less chance of fatigue-related failures.

The original seal design uses a metal bellows to allow axial movement of the stationary seal face. This allows the non-rotating stationary seal face to "follow" the rotating face in and out, if the shaft experiences thrust movement. This design is intricate and expensive to manufacture, but there is very little to go wrong. If the shaft experienced thrust movement, the spring and metal bellows compress and expand without risk of opening the seal faces. The original design had the rotating face of the seal machined into the compressor shaft. The new seal uses a replaceable face which can be removed and replaced without fully tearing down the compressor.

The original seal design with metal bellows and stationary seal face able to follow shaft thrust movement.


This is the rotating seal face, which sits on the shaft shoulder. It turns with the shaft and sits on a rubber washer but does not slide along the shaft.


The second design is less costly to manufacture, by eliminating the metal bellows. In this design, the stationary non-rotating seal face is fixed to a metal plate and cannot move axially. The rotating seal face is mounted to the shaft. Instead of a metal bellows, the rotating face can slide along the shaft. It has a rubber sleeve inside its mounting. The rubber sleeve seals around the shaft, while the spring pushes the seal face against the stationary face. The significant limitation of this design is the rubber sleeve inside the seal. It is exposed to sliding motion each time the shaft experiences thrust movement. This type of seal is very sensitive to shaft movement. If the shaft moves in and out faster than the rubber sleeve can slide, the seal faces open up and leaks occur. The most significant problem is that particles can become trapped between the seal faces, scoring them and causing permanent leaks after one accidental bump on the shaft. This type of seal is what was found in the compressor for this project. The seal was in serviceable condition. It could have worked with lapping of the faces, however the compressor shaft does not have an acceptable surface for this seal to be installed. The area where the rubber sleeve must seal, and slide, is deeply rusted and pitted. Note that these seals are reliable when installed properly on a shaft with adequate surface finish and proper thrust clearances.


This video is in two parts:
Click this link to open YouTube video first half!

Click this link to open YouTube video second half!

 

[turbokinetic]

Yesterday I put the compressor back on the base and reconnected the condensers. I replaced the end of the left condenser, which had the defective flare. Then, I installed the sight glass on the receiver outlet valve; and the filter-drier under the frame. Those two parts got a custom-made copper line to join the two.

(pictures in next post)
The left coil has a new piece where it attaches to the compressor.

The sight glass will help determine low charge amount.

Filter-drier will help trap any contaminants which were not removed during repairs.

The cold control is a visually unique part of these, not used by any other company. It is a fancy pressure switch with many adjustments. Unfortunately the original one was worn and of an early design which used cotter pins as opposed to studs and bushings on the later models. I had a badly deteriorated but less worn example. I took it apart and saved the parts needed to renew this control; plus make a couple improvements. The newer control has a Bakelite cover on the electrical contacts, which prevent shocks. This was transferred to the rebuilt control. The control works like a thermostat, but it uses the pressure of the system refrigerant on the low-side to estimate evaporator temperature. This works because the low-side float system totally stops pressure from the high side from entering the low side when the machine stops. The liquid refrigerant in the evaporator serves the same purpose as the charge in a traditional thermostat sensing bulb.

Rusted control is newer type but badly corroded. Thankfully the important parts are still undamaged.

The "hybrid" control built mainly of original parts.

Test-fit of the control.

ext, the motor got some attention. Being a repulsion-start motor, it has significantly more moving parts inside it compared to a more modern motor. All of these parts have to move smoothly and consistently, or the motor will start inconsistently, spark, sound unpleasant, or do other undesirable things. I am pretty sure this motor was actually rebuilt, or maybe replaced with a new motor shortly before the system was taken out of service. This is based on the condition of the brushes and commutator. There is virtually no wear on these parts. Everything got a good cleaning and it was good to go.

The motor's lead wires were badly deteriorated. To correct that, I extended the wires and then installed heat shrink over them, extending it inside the motor beyond the insulating bushings. This motor was not equipped with a junction box.

The rear bearing was missing a cover over the oil wick. This is important because the oil wick needs a spring to press it against the shaft. The spring is part of this cover. Thankfully I was able to locate one in my parts stash.

Taking out the "shorting necklace" from the motor. This is part of the repulsion-start mechanism. It has to be clean and make contact with the commutator when engaged. The commutator appears new, aside from the black greasy streak where the brushes were riding and oil got on the parts.

You can see a yellow varnish coating on the parts. That is causing the motor to squeak and spark during starting. Brushes are otherwise new.

Installing the new rear bearing cover, with oil wick pressure spring.

Lovely original condition!

The condensing unit base has a very nice belt tensioning system. This bracket with threaded stud can push the motor away from the compressor pump to allow for tightening the belt. No need for a prybar!

Finally, all the parts together, aside from the wiring and a few minor details.

I was able to run it with nitrogen, and the compressor pumps well. The new belt I bought for the project was very shelf-worn and it has a terrible kink in it. It is going to be replaced for one which is not making noise. Other than that, I am very pleased with it. Next phase of the project will be testing. I will mount the evaporator in a test cabinet and make up a set of temporary lines to connect everything up. Then it will get an extended test-run.

Click this link to open YouTube video!

 

[turbokinetic]

I replaced the end of the left condenser, which had the defective flare. Then, I installed the sight glass on the receiver outlet valve; and the filter-drier under the frame. Those two parts got a custom-made copper line to join the two.

The left coil has a new piece where it attaches to the compressor.

The sight glass will help determine low charge amount.

Filter-drier will help trap any contaminants which were not removed during repairs.

 

[turbokinetic]

Got an update today! Yesterday I was able to get this project to the testing phase! Started out by studying an old motor from another similar-vintage system. This motor is 100% original and came from a museum collection at some point in the past. Of note is the protective sleeve over the wiring. It is a cotton and tar material. I actually have a very small amount of new-old-stock sleeve. Plan is to use it to conceal any new wiring on the unit getting rebuilt.

The factory used this arrangement to protect each pair of motor wires. I plan to combine all four wires into one run of sleeve. Tried the two-sleeve approach but it looked sloppy on this setup.

Motor wires through the 100 year old "new" sleeve.

Power cord through the sleeve. It is run-of-the-mill SJ cable inside there.

Circuit breaker and all terminations arranged in junction box.

Box cover in place. Loving how this is looking!

Testing 240V configuration with Acme step-up transformer. Don't tell Wylie Coyote I took his roadrunner-shocker transformer.

The cabinet for this system is built-in in its home. In order to make a meaningful test, the evaporator must be confined in an insulated cabinet. For that purpose, I have an old GE CA-2 Monitor Top cabinet. It has the mandatory RockAuto magnets applied, to signify it is a test cabinet LOL! This condensing unit is too awkward to mount on top, so I strapped together two dollies, and attached a stand to the one on the right side of the picture. It may appear unstable but it is assembled with fasteners.

The best way to charge these units is with a closed receiver outlet valve ("king" valve as it is sometimes called.) Due to the manner in which the float system operates, it will pass a lot of vapor from high side to low side if the system is partially charged. This will add significant heat and load to the unit. By closing this valve, the compressor is only condensing the vapor coming from the cans of refrigerant, but not a freeflowing vapor loop. The sight glass shows bubbles here because I have just opened the receiver outlet and the system is equalizing before starting the compressor.


Continued on next post...

 

[turbokinetic]

Within minutes of startup, we have frost on the evaporator!

The sight glass cleared up nicely. No dirty oil or other cloudy trash circulating.

Thermal image of evaporator. The angle plays tricks on the camera. The whole thing is more or less equally cold. Colder than -10°F (-23°C) to be exact.

The condensing unit isn't too hot. The room is cool since our fall weather is starting. But there are no alarmingly hot areas. This is good!


Here is the video from this day's progress:
Click this link to open YouTube video!

It is so rewarding to get these old systems up and going. Hope you are finding this as interesting as I am!
Sincerely,
David
The next part of the process is to search for leaks using the electronic leak detector. Assuming none are found, then it will be time for dialing in the control. The control adjustment will be preliminary because the heat load characteristics of this cabinet are different from the built-in cabinet it will be permanently installed in. The goal will be consistent operation and running for enough hours to detect any operational problems with the system. It will need several weeks of test time.

 

[turbokinetic]

Got some good news today - the test run is underway!

There are some concerns which will need to be addressed. First is the motor has a small vibration which is, in my opinion, too much. It resonates with the base and causes noise which will be heard when the unit is running. Temporarily, to protect the lines from vibration, I installed some rubber matting under the motor.

I'm satisfied with the pressures in the system, so I tried taking the gauges off and capping the service port. Unfortunately, a cap or other fitting had been installed and overtightened too many times in the past. The threads were bad and a metal cap would not go on. The hose would seal, but only when flipped around and the end typically used at the gauge manifold was used at the unit.

I constructed a new tee fitting by drilling and threading one side for 1/8" NPT. Then, a service port 1/8" NPT by 1/4 Schrader flare was soldered into the threaded port. This was originally a similarly-damaged tee from a similar Frigidaire system!

After installing that, I was able to use a Schrader valve core to make this port extra secure.

Now things are self-contained, sealed, and no gauges connected. The test run can commence!


Click this link to open YouTube video!

Hope you all are enjoying seeing this project coming together!
Sincerely,
David

 

[turbokinetic]

Hope you folks are enjoying reading and watching this project come together. The previous posts were shared on the Monitor Top forum already and then shared here. This is today's status of the project.

In spite of using new-old-stock discharge valves in the compressor rebuild, there was excess reverse flow through the compressor during the off-cycle. This causes the off-cycles to be too short. I could not visually see any defects, but one of the two cylinders was passing. I had another NOS valve plate. This one, I bench tested before installation and found it to be sealing perfectly. That cured the short cycles, but now I have the daunting task of painting the edge of the valve plate without messing up the rest of the unit with paint! Will probably use a small paint brush to take care of that. With that taken care of; the refrigeration system ran well for a couple days, and there are no concerns there. However, I was not satisfied with the level of vibration from the motor. I secured the system and removed the motor's rotor. That has been taken to a shop in Birmingham, AL for dynamic balancing. They have finished with it, and it is due to be picked up Monday. Hopefully the test run can resume at that point, with a quieter system.

No pictures or video but I will update once the rotor is back here.
Sincerely,
David

 

[jamiel]

This is so cool! Have been in a couple homes/mansions in the city of Detroit with functioning built-ins from this period with the remote compressor. Seems like they are more Kelvinator branded up here (which makes sense) than Frigidaire I believe which was from upstate NY at the time.

 

[neptunebob]

What refrigerant are you using now that R12 has been banned for decades?