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Post by turbokinetic on Apr 23, 2019 0:13:10 GMT
This little DRA2 has been running happily for the past three weeks on R124. Today, however, I checked on it and noticed that the the machine was still running despite this: Yes, the evaporator measured at -17.5 F! The cabinet was about 14 inside. That means the evaporator must have been pulled down to at least a 15" vacuum. It looked the contact arm was still in the "on" position, while the bridle was in the "off" position. Physically pressing down the "off" button made the contacts snap open. Who knows how long it was running with the controls stuck 'on'. After an almost 4-hour "off" period, it snapped back on and cycled normally. Interestingly, the dome was just pleasantly warm when I shut it off manually, and the machine sounded happy. Ambient temps were in the mid '70s at the time. All I have to say after all this is ... wow.
Awe man don't we just all love those sticking control situations!
On the positive side, it seems that these machines like long run times every now and then. Probably will have done it some good.
I was fearing that you were going to say ".... contact arm was open and the motor was running because a ground fault in the windings was bypassing the control..." but so thankful that wasn't the case!!!
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Post by ckfan on Apr 23, 2019 20:17:04 GMT
Man, that’s cold! That’s a keeper right there.
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Post by birkie on May 6, 2019 4:02:10 GMT
I shut it off as temperatures were pushing 90 in the garage, and the dome was starting to get hot at the end of each cycle. That being said, it seems like the dome is a little cooler on R124 than SO2. On SO2, the dome started to get equivalently hot when it was around 85. Besides being a bit cooler, the machine seemed overall quieter than on SO2, especially at higher temperatures. When ambient temperatures got around 80 or so, the machine had a sort of "whistling" to tone on SO2, which was completely absent with R124. Here are some videos for comparison under similar conditions SO2 R124 Lastly, I think I'm going to put in a higher wattage heater. One thing that was immediately noticeable was that the rattle upon initial pulldown was a lot worse on R124 than SO2. Here's the worst it got, about a half hour into pulldown. On SO2, I jacked the left side until it stopped rattling, and could eventually put it down to level after a couple cycles. On R124, the rattle caught up with it once I had jacked it as high as I was comfortable. It got better after a couple cycles as well, but man the rattle was bad. I also noticed that the machine got a little choppy (not full-blown rattle) whenever the temperature would swing upward rapidly. The same happened on SO2 to a smaller extent, but on R124 it was definitely noticeable. From this I conclude that the 14W heater currently in it is rather marginal for keeping refrigerant out of the sump whenever conditions are dynamic. I might throw my 18W heater in and see if it makes a difference. Lastly, some shots of the evaporator frost right before I shut it down:
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Post by ckfan on May 6, 2019 11:55:22 GMT
Very good stuff. I hope you can get that rattle to go away.
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Post by coldspaces on May 8, 2019 4:00:16 GMT
Very interesting work! I believe you are on the right track and will be watching to see if extra heat in the oil sump makes a difference. AC compressors normally have 45 watts or more.
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