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Post by ibew716 on Jun 7, 2023 2:24:48 GMT
I was given this flat top refrigerator and a chest freezer of similar vintage about 23 years ago. while the chest freezer is still ticking the flat top crapped out on me around 2018. After doing a bunch of reading at the time I decided that the original M1A162 relay was to blame and held on to my refrigerator hoping that I could resurrect it. I'm a chicken at heart when it comes to things outside my wheelhouse and was unwilling to mess with it then, but recently decided to give it a try.
As with most of these, the wiring is crap so it needs replacement. Since I was unsure of the actual cause of its demise I decided not to completely replace the wiring until I knew that the compressor was still good. As far as I can tell the windings were not shorted to ground, and the start and run windings measured 18 & 4.2 ohms respectively with a total of 22.2 across them. I replaced the wiring to the compressor and purchased an RO-81 start/run relay. I decided to wire power directly to the relay as I still haven't replaced the wiring into the cabinet thru the stat. When I plugged it in, I heard the relay kick after a few seconds, but the compressor never did (as far as I could tell). About 10 seconds after the relay kicked I pulled the plug to avoid any further potential damage after which I heard the relay return to normal.
I'm hoping someone here can tell mem what I might have missed. Is there any way to further test the compressor? Is it completely shot? I know that I can retrofit the compressor but was hoping not to have to do so.
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marko
7 Cubic Foot
Posts: 141
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Post by marko on Jun 7, 2023 9:17:25 GMT
The winding readings add up properly, and you have no short to ground, two good things. Next step for me would be to get a current draw reading with an amp clamp type meter. If the compressor is drawing LRA, then it may be stuck. See if the start winding is drawing current through the relay, if not, jump power to start and if the compressor starts, quickly remove the jump wire. Stuck compressors can sometimes be freed with the use of a large value capacitor.....
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Post by ibew716 on Jun 7, 2023 12:17:24 GMT
Thank you for taking the time. I will look into this as soon as I have the opportunity. I do have a question regarding this procedure.... would one of the 3N1 hard start relays work for something like this? If so, would you expect the addition of the capacitor to be a permanent fix or only to free the motor up initially?
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marko
7 Cubic Foot
Posts: 141
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Post by marko on Jun 7, 2023 13:23:59 GMT
Thank you for taking the time. I will look into this as soon as I have the opportunity. I do have a question regarding this procedure.... would one of the 3N1 hard start relays work for something like this? If so, would you expect the addition of the capacitor to be a permanent fix or only to free the motor up initially? Well, it really all depends upon whether the compressor is stuck, or not. The 3N1 relay/capacitor may be a good permanent option, but first things first. Try to determine what is really wrong, then decide upon a course of action.
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Post by ibew716 on Jun 7, 2023 21:38:17 GMT
Thank you for taking the time. I will look into this as soon as I have the opportunity. I do have a question regarding this procedure.... would one of the 3N1 hard start relays work for something like this? If so, would you expect the addition of the capacitor to be a permanent fix or only to free the motor up initially? Well, it really all depends upon whether the compressor is stuck, or not. The 3N1 relay/capacitor may be a good permanent option, but first things first. Try to determine what is really wrong, then decide upon a course of action.
I finally found a free minute this afternoon to check current on the coils. I check the run coil first and found it to draw about 10A. I unplugged the thing immediately after seeing that value, but noticed the RO-81 was quite warm. I gave it a few minutes to cool down and then checked the start coil. it only registered 4.2A until the relay kicked and it bled down to zero. I expect this means the compressor is locked up. I don't happen to have a capacitor on hand and wouldn't really know where to start (value wise). I did see pg. 127 of the Scotch Yoke service manual discusses "jarring" the compressor by briefly feeding it 240VAC. I don't like the idea... |
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Post by turbokinetic on Jun 7, 2023 21:47:35 GMT
Well, it really all depends upon whether the compressor is stuck, or not. The 3N1 relay/capacitor may be a good permanent option, but first things first. Try to determine what is really wrong, then decide upon a course of action.
I finally found a free minute this afternoon to check current on the coils. I check the run coil first and found it to draw about 10A. I unplugged the thing immediately after seeing that value, but noticed the RO-81 was quite warm. I gave it a few minutes to cool down and then checked the start coil. it only registered 4.2A until the relay kicked and it bled down to zero. I expect this means the compressor is locked up. I don't happen to have a capacitor on hand and wouldn't really know where to start (value wise). I did see pg. 127 of the Scotch Yoke service manual discusses "jarring" the compressor by briefly feeding it 240VAC. I don't like the idea... If the compressor is indeed stuck (which it seems your is,) often a boost with 240V or even higher can free it up. Have had to use 300V or more; with a capacitor on some units. Those have continued to work after freeing up, as well. Capacitor values of 100 to 200uF seem to get the best torque. The trick is not to exceed the thermal damage curve of the motor. This can be accomplished by limiting boost attempts to 1/2 second energized with 30 seconds to rest between. If 5 or 10 boosts don't do the trick, it is probably not going to be freed up at the voltage you are using. The reason these get stuck is due to the corrosive nature of SO2 when moisture gets in the system and they sit for years. Sincerely, David |
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Post by ibew716 on Jun 8, 2023 1:22:42 GMT
I finally found a free minute this afternoon to check current on the coils. I check the run coil first and found it to draw about 10A. I unplugged the thing immediately after seeing that value, but noticed the RO-81 was quite warm. I gave it a few minutes to cool down and then checked the start coil. it only registered 4.2A until the relay kicked and it bled down to zero. I expect this means the compressor is locked up. I don't happen to have a capacitor on hand and wouldn't really know where to start (value wise). I did see pg. 127 of the Scotch Yoke service manual discusses "jarring" the compressor by briefly feeding it 240VAC. I don't like the idea... If the compressor is indeed stuck (which it seems your is,) often a boost with 240V or even higher can free it up. Have had to use 300V or more; with a capacitor on some units. Those have continued to work after freeing up, as well. Capacitor values of 100 to 200uF seem to get the best torque. The trick is not to exceed the thermal damage curve of the motor. This can be accomplished by limiting boost attempts to 1/2 second energized with 30 seconds to rest between. If 5 or 10 boosts don't do the trick, it is probably not going to be freed up at the voltage you are using. The reason these get stuck is due to the corrosive nature of SO2 when moisture gets in the system and they sit for years. Sincerely, David David, Thank you for the advice. It was one of your videos on Youtube that got me to give this a try. SO.... here is the update. With much trepidation I had my neighbors over to help me out this evening. They brought over capacitors just in case and plenty of moral support. We started out making sure we were all on the same page and ultimately attempted to "jar" only the run winding. We only hit it once capturing a high of 16A but heard nothing. on the second attempt we decided to hit both windings. On this attempt, to my amazement we heard the piston free up. for good measure we decided to stop and rewire the relay in to the circuit and hit it with 120V. When we clearly heard the compressor kick on, we gave it a minute and then simply turned the breaker back on at which point the compressor began to quietly hum. After a few minutes the freezer section was cold to the touch with the run winding pulling about 3.2A A few minutes later one of my neighbors indicated that he could smell hot or burning plastic and reached down to touch the RO-81. It was about 100 degrees to the touch. I suspect that maybe I damaged it during prior testing? At any rate I figure that I can pick up another one and give it a try. if this thing will continues to work I planned to replace the RO-81 with a mechanical relay and overload. I'd like to Thank you and Marko for keeping my at it. Any further thoughts on the relay? |
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Post by turbokinetic on Jun 8, 2023 13:06:39 GMT
If the compressor is indeed stuck (which it seems your is,) often a boost with 240V or even higher can free it up. Have had to use 300V or more; with a capacitor on some units. Those have continued to work after freeing up, as well. Capacitor values of 100 to 200uF seem to get the best torque. The trick is not to exceed the thermal damage curve of the motor. This can be accomplished by limiting boost attempts to 1/2 second energized with 30 seconds to rest between. If 5 or 10 boosts don't do the trick, it is probably not going to be freed up at the voltage you are using. The reason these get stuck is due to the corrosive nature of SO2 when moisture gets in the system and they sit for years. Sincerely, David David, Thank you for the advice. It was one of your videos on Youtube that got me to give this a try. SO.... here is the update. with much trepidation I had my neighbors over to help me out this evening. They brought over capacitors just in case and plenty of moral support. We started out making sure we were all on the same page and ultimately attempted to "jar" only the run winding. We only hit it once capturing a high of 16A but heard nothing. on the second attempt we decided to hit both windings. On this attempt, to my amazement we heard the piston free up. for good measure we decided to stop and rewire the relay in to the circuit and hit it with 120V. When we clearly heard the compressor kick on, we gave it a minute and then simply turned the breaker back on at which point the compressor began to quietly hum. After a few minutes the freezer section was cold to the touch with the run winding pulling about 3.2A A few minutes later one of my neighbors indicated that he could small hot or burning plastic and reached down to touch the RO-81. it was about 100 degrees to the touch. I suspect that maybe I damaged it during prior testing? At any rate I figure that I can pick up another one and give it a try. if this thing will continue to work I planned to replace the RO-81 with a mechanical relay and overload. I'd like to Thank you and Marko for keeping my at it. Any further thoughts on the relay? Awesome! That is the best news! As for the RO81, these use a thermal device to switch off the start winding. It is a special ceramic material which gains resistance as it heats up. It is called a PTC (positive temperature coefficient) resistor. When cold, it passes current to the start winding. Once power is on, the PTC device passes power and starts heating up. After a few seconds, it's hot enough to change in resistance. It then starts limiting the current in the start winding. After this point, a small current (milliamps) flows throught he PTC device to keep it hot and therefore keep the start winding "off" while running. It is normal for the RO81 to get very hot while the compressor is running. It will need about 5 minutes to cool down after any run, before it is ready for the next start. Hope it stays working well for you! If you want to, you could rebuild the original relay to get away from the limitations of that relay. People sometimes send them to certain members here to get them redone. I can do it as can a few others here. Sincerely, David |
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Post by ibew716 on Jun 8, 2023 14:10:11 GMT
David, Thank you for the advice. It was one of your videos on Youtube that got me to give this a try. SO.... here is the update. with much trepidation I had my neighbors over to help me out this evening. They brought over capacitors just in case and plenty of moral support. We started out making sure we were all on the same page and ultimately attempted to "jar" only the run winding. We only hit it once capturing a high of 16A but heard nothing. on the second attempt we decided to hit both windings. On this attempt, to my amazement we heard the piston free up. for good measure we decided to stop and rewire the relay in to the circuit and hit it with 120V. When we clearly heard the compressor kick on, we gave it a minute and then simply turned the breaker back on at which point the compressor began to quietly hum. After a few minutes the freezer section was cold to the touch with the run winding pulling about 3.2A A few minutes later one of my neighbors indicated that he could small hot or burning plastic and reached down to touch the RO-81. it was about 100 degrees to the touch. I suspect that maybe I damaged it during prior testing? At any rate I figure that I can pick up another one and give it a try. if this thing will continue to work I planned to replace the RO-81 with a mechanical relay and overload. I'd like to Thank you and Marko for keeping my at it. Any further thoughts on the relay? Awesome! That is the best news! As for the RO81, these use a thermal device to switch off the start winding. It is a special ceramic material which gains resistance as it heats up. It is called a PTC (positive temperature coefficient) resistor. When cold, it passes current to the start winding. Once power is on, the PTC device passes power and starts heating up. After a few seconds, it's hot enough to change in resistance. It then starts limiting the current in the start winding. After this point, a small current (milliamps) flows throught he PTC device to keep it hot and therefore keep the start winding "off" while running. It is normal for the RO81 to get very hot while the compressor is running. It will need about 5 minutes to cool down after any run, before it is ready for the next start. Hope it stays working well for you! If you want to, you could rebuild the original relay to get away from the limitations of that relay. People sometimes send them to certain members here to get them redone. I can do it as can a few others here. Sincerely, David David, If I could get this thing running, I had planned to replace my original M1A162 relay making use of the original housing using the method that coldspaces details in this link ( monitortop.freeforums.net/thread/37/ge-type-relay-modernization ). Are you suggesting that you can actually rebuild the original relay replacing worn out coils, bimetallic strips, and such instead of replacing these parts with modern replacements? If so, what could I expect that to cost? How long does it take? |
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Post by turbokinetic on Jun 8, 2023 15:30:24 GMT
Awesome! That is the best news! As for the RO81, these use a thermal device to switch off the start winding. It is a special ceramic material which gains resistance as it heats up. It is called a PTC (positive temperature coefficient) resistor. When cold, it passes current to the start winding. Once power is on, the PTC device passes power and starts heating up. After a few seconds, it's hot enough to change in resistance. It then starts limiting the current in the start winding. After this point, a small current (milliamps) flows throught he PTC device to keep it hot and therefore keep the start winding "off" while running. It is normal for the RO81 to get very hot while the compressor is running. It will need about 5 minutes to cool down after any run, before it is ready for the next start. Hope it stays working well for you! If you want to, you could rebuild the original relay to get away from the limitations of that relay. People sometimes send them to certain members here to get them redone. I can do it as can a few others here. Sincerely, David David, If I could get this thing running, I had planned to replace my original M1A162 relay making use of the original housing using the method that coldspaces details in this link ( monitortop.freeforums.net/thread/37/ge-type-relay-modernization ). Are you suggesting that you can actually rebuild the original relay replacing worn out coils, bimetallic strips, and such instead of replacing these parts with modern replacements? If so, what could I expect that to cost? How long does it take? Ordinarily, the only part which goes bad are the contact points for the start function. If those are worn out, I can replace them with new contact points. If other parts are damaged, I have an assortment of "parts relays" which can be used for those items. Have you opened the old relay to inspect it? If you can send pictures I can give you an idea of what it would cost. |
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Post by ibew716 on Jun 8, 2023 17:48:39 GMT
David, If I could get this thing running, I had planned to replace my original M1A162 relay making use of the original housing using the method that coldspaces details in this link ( monitortop.freeforums.net/thread/37/ge-type-relay-modernization ). Are you suggesting that you can actually rebuild the original relay replacing worn out coils, bimetallic strips, and such instead of replacing these parts with modern replacements? If so, what could I expect that to cost? How long does it take? Ordinarily, the only part which goes bad are the contact points for the start function. If those are worn out, I can replace them with new contact points. If other parts are damaged, I have an assortment of "parts relays" which can be used for those items. Have you opened the old relay to inspect it? If you can send pictures I can give you an idea of what it would cost. ![]() I don't know if my the photos attached, but they don't appear while making my reply, so here's hoping. I haven't checked the manual yet to determine what the resistance should be across the relay's coil, but I measured it at .5 ohms. FWIW my meter could use some slight calibration. I noticed when I metered across the hot plastic insulated hot wire in the relay housing I was reading .2 ohms and I pretty sure that it is just an insulated splice. |
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Post by turbokinetic on Jun 8, 2023 18:10:59 GMT
Those pictures came through. It seems that the relay contacts are worn but not gone. The white dusty look around the overload points (on the side with the silver resistance grid) indicates that has been tripping and resetting over and over. It's possible that the points on the start relay side (operated by the series coil) are not making contact, however I expect they are still making contact. It may be that the compressor got stuck and this caused the relay to cycle off and on with the overload.
If I were you, I would try that relay and see what happens. It will probably work fine now that the compressor has been un-stuck.
Bear in mind these relays have to be mounted upright. One end has to face up, as marked on the relay cover. If it is not oriented correctly, it will malfunction and the overload will trip.
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Post by ibew716 on Jun 8, 2023 19:34:59 GMT
Thank you for having a look. should I be worried about that diagnosis? I guess I wonder what would cause the motor to lock up in the first place. In the meantime I am running this thing through a cycle to see how it performs its getting cold, so that's a plus.
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Post by turbokinetic on Jun 8, 2023 21:10:35 GMT
Thank you for having a look. should I be worried about that diagnosis? I guess I wonder what would cause the motor to lock up in the first place. In the meantime I am running this thing through a cycle to see how it performs its getting cold, so that's a plus. I wouldn't worry about it too much. If you find that the cooling is intermittent you may need to search for a low-side leak where air seeped into the system. More than likely the stuck compressor happened due to sitting too long without running. |
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Post by ibew716 on Jun 10, 2023 21:25:44 GMT
Thank you for having a look. should I be worried about that diagnosis? I guess I wonder what would cause the motor to lock up in the first place. In the meantime I am running this thing through a cycle to see how it performs its getting cold, so that's a plus. I wouldn't worry about it too much. If you find that the cooling is intermittent you may need to search for a low-side leak where air seeped into the system. More than likely the stuck compressor happened due to sitting too long without running. Now that I this unit has been resurrected, I'd like to restore it as best I can. I started this morning by rewiring it. When I got to the top of the cabinet I determined that the wiring to the lamp and switch were in excellent shape, so I left them alone choosing to replace the wiring between the relay and the top of the cabinet only. the original wirenuts were in good shape as well so I reused them and wished that I had some friction tape on hand to complete the original appearance. I intend to completely repaint as this thing has been painted a couple of different times and steel is showing. Mine is a glyptal painted machine so I'm not ruining a porcelain finish. I would like to know if there is a specific glyptal paint color match for the original. The thing I am most concerned about is that I would like to disassemble the door to paint it. Some of the textolight screws do not want to come out and I don't want to strip them. I have even considered re-chroming the door hardware. Is this a bad idea? Before I close it back up I will be replacing the gaskets on top as well as on the door and any insulation that you guys recommend. I noted that the original insulation in mine looked to be in OK shape. it looks as though it may have gotten wet at some point, but overall looks pretty good, if not discolored. the steel pan underneath looks nearly pristine with the exception of a a bit of rust on the square nuts fastening it to the cabinet below. Unlike many of the photos I've seen of cellulose insulation surrounding the float bowl, mine was wrapped in some kind of impregnated gauze looking material. Is that OK or should it be replaced or perhaps supplemented? sorry I recognize there is a lot to uppack here. |
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