dan57
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Posts: 2
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Post by dan57 on Aug 29, 2020 18:11:15 GMT
I have a TYPE CA-1-B16 monitor top.
When I plug it in it sounds like it wants to start but shuts down almost right away.
Any suggestions on what the problem could be?
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Post by cablehack on Aug 29, 2020 23:44:45 GMT
This is a common characteristic of CA units. First thing is to ensure the oil heater in the base of the compressor is working. With the machine switched off at the control, measure the resistance across the plug pins of the power cord. A reading of around 900 to 1000 ohms will indicate the heater is OK. A reading much higher or infinity will show the heater is open circuit (very common). Alternatively, a plug in power meter will show a constant draw of around 12W with the machine off, if the heater is OK. In simple terms, CA's don't like to start with cold compressor oil because methyl formate is then in liquid form and cannot be compressed.
If, once you know the heater is working, leave it on for a few hours with the control off. If the machine still has difficulty starting, the next likely cause is the build up of non condensible gas. This is extremely common, and something virtually every CA owner will have to deal with at some time.
In a few instances the compressors have been seized up because of the motor bushings. However, they can often still be freed up.
First thing though is to establish the oil heater is working, and we can go from there.
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Post by turbokinetic on Sept 2, 2020 7:38:27 GMT
I have a TYPE CA-1-B16 monitor top. When I plug it in it sounds like it wants to start but shuts down almost right away. Any suggestions on what the problem could be? Hi Dan. In addition to what Cablehack said; can you describe how the failure happened? Did you just obtain the unit and it doesn't run? Or has it been working and you noticed it getting intermittent? It is always possible that the start-relay is going bad, as well. That can prevent it from starting up. |
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dan57
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Post by dan57 on Sept 18, 2020 12:48:54 GMT
When I got the unit it was not working.
It was a hand me down.
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tmy17
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Posts: 5
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Post by tmy17 on Sept 20, 2020 3:54:24 GMT
I recently got a CA-2-B16 that pulls about 1000 Watts for a few minutes before it stalls or I shut it off when I see the power climb to >1200 Watts. My suspicion is that the pressure is high and climbs even higher until the compressor can't handle it. I've tried purging but not sure I'm doing it right. I see gas bubbling out even when it's off but I'm in South Florida and the workshop is generally in the high 80s to low 90s so maybe that's normal CA behavior. I don't think it has a working heater but at that ambient temperature I wasn't sure if it was needed. The start relay doesn't usually engage but the compressor seems to run anyway. I tried forcing the relay to connect for a second or two but it doesn't seem to make any difference. Any ideas?
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Post by turbokinetic on Sept 20, 2020 4:54:16 GMT
I recently got a CA-2-B16 that pulls about 1000 Watts for a few minutes before it stalls or I shut it off when I see the power climb to >1200 Watts. My suspicion is that the pressure is high and climbs even higher until the compressor can't handle it. I've tried purging but not sure I'm doing it right. I see gas bubbling out even when it's off but I'm in South Florida and the workshop is generally in the high 80s to low 90s so maybe that's normal CA behavior. I don't think it has a working heater but at that ambient temperature I wasn't sure if it was needed. The start relay doesn't usually engage but the compressor seems to run anyway. I tried forcing the relay to connect for a second or two but it doesn't seem to make any difference. Any ideas? Sadly, the issue with the start relay not working is very bad omen. There is probably a short where the start winding is always energized; thereby allowing the compressor to start without the relay, and proceed to overheat after starting. Unfortunately, this is often the symptom of a partially burned winding in the compressor motor. Disconnecting the start relay and testing at that point can be one way to determine what is going on. |
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tmy17
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Post by tmy17 on Sept 20, 2020 15:40:42 GMT
I just measured the coil resistance of start and run windings. Start is 21.1 Ohms and Run is 3.3 Ohms - which seems pretty low. What's even worse: I found that if I disconnected the start and run leads from the relay base and just connected 110 to the red run lead, it would hum and pull around 800+ Watts but wouldn't start. If I also connected the start lead to 110, it would run, pulling about 1200 Watts but stops immediately after removing the start lead power. I held it there for a couple of seconds once to see if it just needed to get the motor up to speed, but no luck. I supposed it's possible there's an external short on the run lead that I could fix but I doubt it. If the motor is fried, what are my options for saving this old machine?
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Post by turbokinetic on Sept 20, 2020 23:20:29 GMT
I just measured the coil resistance of start and run windings. Start is 21.1 Ohms and Run is 3.3 Ohms - which seems pretty low. What's even worse: I found that if I disconnected the start and run leads from the relay base and just connected 110 to the red run lead, it would hum and pull around 800+ Watts but wouldn't start. If I also connected the start lead to 110, it would run, pulling about 1200 Watts but stops immediately after removing the start lead power. I held it there for a couple of seconds once to see if it just needed to get the motor up to speed, but no luck. I supposed it's possible there's an external short on the run lead that I could fix but I doubt it. If the motor is fried, what are my options for saving this old machine? This is a strange set of symptoms. The resistances sound OK. Was there any continuity to ground? When you inspect the start-relay, are there any signs of the varnish burned off the relay coil winding? Sometimes people bypass the overload breaker in the control, and the result is the motor and the start relay being burned. If the relay is burned, it means the same current flowed in the motor, indicating it is likely damaged. Another possibility is extreme non-condensable gas pressure which stalls the compressor after it no longer has the benefit of the start winding. One way to pre-purge an extremely pressurized unit is to place it in a cool environment below 80°F, and let it equalize with the room temperature over night. The next day, before any start attempts, open the bleeder. Ensure there is really pressure escaping by using the oil in the port, as instructed in the manual. As long as pressure is escaping, keep the port open. It may take quite a long time. As long as the temperature is below the boiling point of the refrigerant (85°F) there will be minimal loss of refrigerant. Once no more gas escapes, close the bleed screw and make another start attempt. If it stays running, you should continue the factory-provided "normal" NCG bleeding method until the condenser is uniformly warm. If this doesn't help it, then you would be looking at a fill rebuild. This would be very costly since these use a welded hermetic housing. Sincerely, David |
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tmy17
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Post by tmy17 on Sept 20, 2020 23:37:52 GMT
Thanks, that sounds like an excellent suggestion. I'll give it a try when I can get the beast moved into air-conditioning. Doesn't seem to be short to ground. From start wire to ground (screw on porcelain side) it was around 20MOhm, similar resistance to cabinet top. Run wire to same side screw is about 500 KOhm, To cabinet top is about 2 MOhm. I imagine a short would look like Ohms or ten of Ohms. I can't really tell if the start relay is burned, there's a small amount of back residue on the laminate but not much and no obvious burn smell. it did actually work a couple of times early on but the contact bounced several times before resting in the de-energized state. The contact itself is pretty pitted and I haven't attempted to clean it up yet.
I was also wondering if it might be a ton of NCG but no experience with these yet. Guess we'll find out with your test.
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Post by cablehack on Sept 21, 2020 0:32:15 GMT
I just measured the coil resistance of start and run windings. Start is 21.1 Ohms and Run is 3.3 Ohms - which seems pretty low. Those resistance values appear low because they're DC measurements. When the motor is fed with AC, and running at normal speed, the 'resistance' will be much higher. As for the motor not continuing to run with the start winding disconnected, that would seem to me that it can't get up to enough speed due to excessive load. Sounds like it needs a really good purge (and a working oil heater). In a warm climate the effects of NCG's tend to be more evident also. |
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tmy17
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Post by tmy17 on Sept 25, 2020 1:41:01 GMT
I managed to purge a lot of gas around 4:00 AM when it was cool enough in the shop. Now the compressor will run on just the start winding and my current has plummeted from 1000 -1200 Watts to around 260-300W. Still high, but what an improvement! The condenser is now getting pretty warm at the top, and a little warm at the bottom. There's a hint of cooling from the evaporator but not much yet. I'd say she has a little rattle so it appears I have more purging to do. I've started doing the 3-minute-open-1-minute-closed routine. I wonder when was the last time she was purged? Thanks for the advice on static purging, David, and the coil resistance, cablehack. I also still need a heater but I might make one from some 10W resistors.
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Post by turbokinetic on Sept 25, 2020 8:28:34 GMT
I managed to purge a lot of gas around 4:00 AM when it was cool enough in the shop. Now the compressor will run on just the start winding and my current has plummeted from 1000 -1200 Watts to around 260-300W. Still high, but what an improvement! The condenser is now getting pretty warm at the top, and a little warm at the bottom. There's a hint of cooling from the evaporator but not much yet. I'd say she has a little rattle so it appears I have more purging to do. I've started doing the 3-minute-open-1-minute-closed routine. I wonder when was the last time she was purged? Thanks for the advice on static purging, David, and the coil resistance, cablehack. I also still need a heater but I might make one from some 10W resistors. Very glad things are moving forward for you! One other issue these can suffer is a worn out float valve seat. If there is a constant percolating or "blowing" or "rushing" noise from the evaporator you may be looking at a cap tube conversion or a float valve rebuild. |
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Post by ChrisJ on Sept 25, 2020 11:00:36 GMT
I managed to purge a lot of gas around 4:00 AM when it was cool enough in the shop. Now the compressor will run on just the start winding and my current has plummeted from 1000 -1200 Watts to around 260-300W. Still high, but what an improvement! The condenser is now getting pretty warm at the top, and a little warm at the bottom. There's a hint of cooling from the evaporator but not much yet. I'd say she has a little rattle so it appears I have more purging to do. I've started doing the 3-minute-open-1-minute-closed routine. I wonder when was the last time she was purged? Thanks for the advice on static purging, David, and the coil resistance, cablehack. I also still need a heater but I might make one from some 10W resistors. What are you using to measure wattage? Current X Voltage won't be even close to accurate. Just off the top of my head, amps x volts x 0.6 should give a more accurate result. |
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Post by cablehack on Sept 25, 2020 22:58:48 GMT
Now the compressor will run on just the start winding Don't do that for more than a few seconds or it will burn out. The start winding is of smaller gauge wire and is not meant for continuous use. There was someone in the flickr group who did that with his Flat Top. Because he wanted to run the fridge without a relay, he ended up with a burnt out motor. |
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