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Post by thedman on Jul 7, 2019 15:40:02 GMT
Just got my first monitor top home. The ad says it was professionally restored by the previous owner. It was left in the house and the new home owners don't want it. I have no idea what "restored" means anymore as the door gasket is hard, there are two racks missing and I'm sure the top seal needs to be replaced (what is that waxy stuff?).
How do you find out what kind of refrigerant was used in it?
Best regards and thank you for your help.
Donald Cochrane philcokid@gmail.com
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btfarm
7 Cubic Foot
Posts: 103
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Post by btfarm on Jul 7, 2019 23:51:50 GMT
Make a pallet for the top. I don't know the dimensions for a CA but I know a knowledgeable member on those will check in. You might post in The FB group if you do FB and maybe get a quicker answer and take a look at the pallet I built for my latest CK.
Mike Nash
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Post by cablehack on Jul 8, 2019 1:55:09 GMT
The way I moved mine was to lay the top on its side on some padded material. Be careful lifting the top off the cabinet because the high side line into the evaporator is liable to get hooked under the lip of the cabinet. When it gets torn off, you have a big job ahead of you, so best be careful. Likewise, when replacing the top back on the cabinet be very careful or it will get crushed. Others have made a crate to support the top upright which is a better way to do it if you can. But, both my tops survived travelling long distances on their side. The refrigerant in all CA's is originally Methyl Formate. There's a label attached to the start relay (form B) or cabinet top (form A) which indicates this and the quantity used. www.flickr.com/photos/13469158@N05/8443435588/in/album-72157633054793795/www.flickr.com/photos/13469158@N05/6866320067/in/album-72157633054818403/
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Post by thedman on Jul 8, 2019 2:56:16 GMT
Thank you for the tips. We ended up using blocks covered with moving blankets and lot's of straps to get it home in the upright position. Dang that thing was heavy... I ordered new feet already as 3 of these are missing. I'm going to need new gasket material and I will have to study the top seal better in the morning light.
Thanks again, Donald
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Post by turbokinetic on Jul 8, 2019 3:30:41 GMT
Hi Donald. It's always interesting what someone considers "restored" in this day and age!
The CA type machines used a very unique and special cooling system. It has maintenance requirements which are very different from most other machines. The refrigerant is a compound called Methyl Formate. It is still available but is very difficult to obtain. There only one supplier and they are picky about who they sell it to.
Search "non condensable gas purge" and you will find a lot of information on the CA maintenance requirements. The system operates in a vacuum. The Methyl Formate is a liquid under normal conditions. The compressor of the CA is more like a vacuum pump. It draws a vacuum in the evaporator, thereby causing the refrigerant to boil and get cold. Whereas most refrigerator systems of this era run at roughly atmospheric pressure in the evaporator; and significant pressure in the condenser - the CA runs at a strong vacuum in the evaporator and roughly atmospheric pressure in the condenser.
They also depend heavily on a functional crankcase heater. Be sure that is working correctly or the compressor may seize up because the refrigerant collects in the lubricating oil sump. It is water-like in consistency and is a lousy lubricant. The heater keeps it where it belongs, and not in a layer beneath the oil.
Sincerely, David
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Post by thedman on Jul 8, 2019 14:25:26 GMT
Hi David, How do you figure out if the heater works? Ohm it?
Donald
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Post by elec573 on Jul 8, 2019 15:59:07 GMT
Yes to check heater an ohm meeter is the easiest way . Unplug fridge turn the switch to off go to the prongs on the cord or on the relay in a dr case and measure the resistance there . Should be around 1000 ohms give or take and remain constant. The heater is always on when the fridge is plugged in. Most of them are not working after 80 plus years . Look in suppler section to order a new one . The wiring most likely will need replacing also . Read through the ca section it we’ll help you out a lot , and answer a lot of questions for you.
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Post by turbokinetic on Jul 8, 2019 16:29:57 GMT
Yes to check heater an ohm meeter is the easiest way . Unplug fridge turn the switch to off go to the prongs on the cord or on the relay in a dr case and measure the resistance there . Should be around 1000 ohms give or take and remain constant. The heater is always on when the fridge is plugged in. Most of them are not working after 80 plus years . Look in suppler section to order a new one . The wiring most likely will need replacing also . Read through the ca section it we’ll help you out a lot , and answer a lot of questions for you.
Yes, this! The heater has about 1KΩ (1000 Ω) of resistance. With the thermostat in the "off" position, the resistance of the compressor motor won't interfere with the measurement. Turn the control OFF and measure resistance between the two power cord pins. If the resistance is higher than 2000Ω it is a bad heater. If the resistance is in the single-digits of ohms (4 or 5 or even 10Ω) then the control is not in the OFF position and the compressor motor is in the circuit.
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Post by thedman on Jul 8, 2019 18:58:27 GMT
Thank you for the help. I noticed there are two plugs on the cord. Why two? The guys will be here in a few minutes to help me unload the beast into the garage.
Donald
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Post by turbokinetic on Jul 8, 2019 19:55:44 GMT
Thank you for the help. I noticed there are two plugs on the cord. Why two? The guys will be here in a few minutes to help me unload the beast into the garage. Donald So; for the plugs - one of them goes to the cooling unit; and the other one goes to the back of the cabinet, to power an interior light.
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Post by thedman on Jul 8, 2019 21:38:08 GMT
She's in... I haven't plugged her in yet but I have one very important question... There is a small ceramic capacitor across two of the terminals at the top plug. It is only pushed thru the little holes in the pins, not soldered ( revision: It's not a cap, after putting my glasses on, it's a lead seal). Also, where should I put the two settings to start? Switch is off, unplugged, 861 ohms across the two top pins. Good to go? Nuther' question. They took the doors and hinges off. There seems to be a difference in the hinges. I'm trying to figure out which one goes on the top and which is the bottom.
Again, thank you for the education.
Donald
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Post by turbokinetic on Jul 9, 2019 0:55:21 GMT
She's in... I haven't plugged her in yet but I have one very important question... There is a small ceramic capacitor across two of the terminals at the top plug. It is only pushed thru the little holes in the pins, not soldered ( revision: It's not a cap, after putting my glasses on, it's a lead seal). Also, where should I put the two settings to start? Switch is off, unplugged, 861 ohms across the two top pins. Good to go? Nuther' question. They took the doors and hinges off. There seems to be a difference in the hinges. I'm trying to figure out which one goes on the top and which is the bottom. Again, thank you for the education. Donald That's interesting about the seal over the plug pins. Never seen that on the pins themselves; but usually on the little screw holding the cover on the relay. If that were on the plug pins, it would probably short out the cord.
The 861Ω is great. Sounds like a good heater! Plug her in with the switch OFF overnight to preheat.
As for the hinges; they should be the same; but I am not an expert on all the different cabinet options. Could be something different going on.
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Post by cablehack on Jul 9, 2019 1:06:29 GMT
It appears the heater is OK. Best to let it warm up for a few hours before starting the compressor. To do this, turn the control to "Off" and plug the fridge in. After a few hours turn to "On" and if all is well it will start up and start cooling. The thermostat is typically set to "5" to start with. I recommend a plug in power meter to use with you fridge. It will tell you at all times that the heater is good (a power draw of around 14W when the compressor is not running), and also how the refrigeration circuit is working. For example, an increase in power consumption above normal can indicate excess non condensible gas building up. And that leads to another thing; at some stage you'll have to purge the NCG's. For this the special Bristol key to fit the charge valve is required. It's easiest to get this in one of the "Hermetic" kits that appear on ebay. Once the fridge is running, check the frost pattern on the evaporator. Both header tanks should have frost to about halfway up (or higher), and the evaporator itself should have an even coating of frost. If not, it's an indication of NCG's being present - this is inherent with the use of Methyl Formate and comes about because MF is unstable and decomposes when used as a refrigerant. The lead seal looks like this www.flickr.com/photos/13469158@N05/8578438695/in/album-72157633054793795/As for the hinges, the upper one (marked "O") causes the door to spring open, while the lower one (marked "R") works in reverse to counteract that so the door doesn't swing open too far. When installed correctly, the door lightly springs open when you step on the pedal. A description of the hinges is given from p164-167 in the Scotch Yoke manual, downloadable here monitortop.freeforums.net/thread/15/service-manual
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Post by thedman on Jul 9, 2019 1:11:12 GMT
Got the hinges on and the door works. I'm not sure why the difference but, they work... I had the heater running for 4 hours before I started her up. She's purring nicely so far. I set it to 5 and put a thermometer in the bottom. We'll she what happens. Tomorrow, I might try the bleeding trick, depending on what I find in the morning. This is an awesome group. Thank you for the great suggestions.
Thanks again, Donald
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Post by turbokinetic on Jul 9, 2019 1:45:08 GMT
Got the hinges on and the door works. I'm not sure why the difference but, they work... I had the heater running for 4 hours before I started her up. She's purring nicely so far. I set it to 5 and put a thermometer in the bottom. We'll she what happens. Tomorrow, I might try the bleeding trick, depending on what I find in the morning. This is an awesome group. Thank you for the great suggestions. Thanks again, Donald Great deal! Hope to hear positive outcome in the morning!
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