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Post by Travis on Mar 4, 2014 6:20:37 GMT
I have been messing around with the 80 fin DR3 unit for the past couple years. For those of you that were on the flickr site, you may remember it as coming on a 3 door cabinet. When it got here it worked, but needed rewiring, new heater, and a new capacitor. The heater leads broke off the heater. I ended up having to chip out the heater and suck out the pieces with a vacuum. I am afraid to actually cut a refrigeration line, so I removed the screws that hold the lower deck to the upper on three sides and gently separated the two. I used a hoist for that. I replaced the heater and the leads to the cap block. I also sleeved the compressor leads with heat shrink tubing. When I got it all back together, I let the heater warm the unit for a couple days. Finally, I turned it on. It ran fine for a couple weeks. After that, it would occasionally arc when it started. I checked the contact points, but couldn't make it better. There seemed to be some low voltage on the dome when it was running. I wondered and worried what was breaking down. Finally after five weeks, I came home to find the overload had tripped. It would try to start, but wouldn't run. I have spoken to John and sent him more emails than he cares to think about. I have watched intently at coldspaces (Gill) experimentation with R12 and later 134a and the DR. We're fortunate here to have many talented members. I reached out to Gill the other week to offer him some CA units. In our conversation, this dead DR3 came up. I guess it's now time to get the party started and see if it can be saved.  |
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Post by jhigdon2 on Mar 4, 2014 6:47:24 GMT
Heck yeah! Let's dive into this one. It's a double pig! One of my favorites and most challenging!
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Post by Travis on Mar 4, 2014 6:53:05 GMT
Thanks John for the encouragement! I will get up to Gill soon. It's freezing here.
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Post by coldspaces on Mar 4, 2014 6:56:11 GMT
Yep Travis is relatively close to me in the realm of the monitor top, so I agreed to take a look and see what can be done. At this point we plan for the DR3 to travel sometime to me to be hopefully brought back to life. My understanding is it has been checked and has a bad run winding so it will probably not be an overnight fix.
Coldspaces
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Post by jhigdon2 on Mar 4, 2014 7:26:57 GMT
When shipping these, make sure to support the evaps, the evap mounting plate and the compressor base equally, so that the evap mounting plate don't come loose. The evaps are heavy and they can pull the (probably rusted) screws out of the (probably rotted) wood. This will also break the steel nipple off the evap, releasing the refrigerant charge. (been there done that).
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Post by Travis on Mar 4, 2014 16:48:19 GMT
John,
Got that. I will drive it there. I will block the evaps. The screws are new and stainless. They will be so easy to Gill to remove.
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Post by allan on Mar 4, 2014 23:12:42 GMT
I have been messing around with the 80 fin DR3 unit for the past couple years. For those of you that were on the flickr site, you may remember it as coming on a 3 door cabinet. When it got here it worked, but needed rewiring, new heater, and a new capacitor. The heater leads broke off the heater. I ended up having to chip out the heater and suck out the pieces with a vacuum. I am afraid to actually cut a refrigeration line, so I removed the screws that hold the lower deck to the upper on three sides and gently separated the two. I used a hoist for that. I replaced the heater and the leads to the cap block. I also sleeved the compressor leads with heat shrink tubing. When I got it all back together, I let the heater warm the unit for a couple days. Finally, I turned it on. It ran fine for a couple weeks. After that, it would occasionally arc when it started. I checked the contact points, but couldn't make it better. There seemed to be some low voltage on the dome when it was running. I wondered and worried what was breaking down. Finally after five weeks, I came home to find the overload had tripped. It would try to start, but wouldn't run. I have spoken to John and sent him more emails than he cares to think about. I have watched intently at coldspaces (Gill) experimentation with R12 and later 134a and the DR. We're fortunate here to have many talented members. I reached out to Gill the other week to offer him some CA units. In our conversation, this dead DR3 came up. I guess it's now time to get the party started and see if it can be saved. Nice crate! Just worked on a single evap DR3 yesterday that was for sale and in very bad condition. Did get it to run but evap would not get very cold. Amazingly it has a single stainless steel evap with a mirror finish, first one I ever seen. |
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Post by Travis on Mar 5, 2014 6:30:39 GMT
Allan,
Thank you for the crate compliment. Unfortunately, I neglected to account for the cap block, so the side panel won't fit. I can still get it to Gill and get all sorts of funny looks along the way.
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Post by coldspaces on Mar 5, 2014 13:18:29 GMT
Allan, Thank you for the crate compliment. Unfortunately, I neglected to account for the cap block, so the side panel won't fit. I can still get it to Gill and get all sorts of funny looks along the way. That's funny, last night I was thinking that if you put the cover on no one will know whats inside. Wish I could ride in the back with it and watch peoples faces. Coldspaces |
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Post by Travis on Mar 5, 2014 23:25:25 GMT
John,
I realize much of this evacuation and opening this up is more or less basic refrigeration practice. I am concerned about contamination and rusting. How do you typically prepare to open the dome to minimize issues?
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Post by allan on Mar 5, 2014 23:59:22 GMT
John, I realize much of this evacuation and opening this up is more or less basic refrigeration practice. I am concerned about contamination and rusting. How do you typically prepare to open the dome to minimize issues? Not sure how the other guys do it but I know you don't want the SO2 to combine with any moisture in the compressor and float so I always expell the SO2 after heating the evap and compressor with my 500 watt floodlight. Be careful you don't want your nose or anyone else's to experience any SO2!!! Once it's good and hot and at zero psi I add dry nitrogen to 40 psi with the unit tilted back to assure the float seat is open. Then I blow that and vacuum system for 20 minutes. Repeat that a couple of times and it should be ready for open heart surgery. May be overkill but when I spend a lot of time on these babies I want them to live a long time and don't want to take chances with contamination |
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Post by coldspaces on Mar 6, 2014 2:05:50 GMT
Are the components more likely to rust because they have been exposed to so2? Doing the vac and nitrogen purges is not a big deal, but does that guarantee things wont rust? I was already planning to heat it first so it is above the dew point of the surrounding air. I was thinking maybe we could seal it in plastic with some desiccant inside while it is open and not being worked on. Thought maybe the bags of desiccant they sell to hang in a closet that can be heated and rejuvenated might be reasonable priced compared to just opening up refrigeration driers.
Coldspaces
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Post by jhigdon2 on Mar 6, 2014 2:32:22 GMT
I have usually waited until summer and did all evac and nitrogen purge outside in the heat. Then let it sit for a day to get good and hot. I have even tried wrapping the unit in black plastic to take advantage of the sun. S02 is very stubborn and it seems that no matter how thorough I have been with evacuating, they still make me take a few steps back when I open the case. I live in a dry climate and in summer humidity is very low, so I have never had one rust. The parts have always stayed real clean.
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Post by Travis on Mar 8, 2014 5:34:48 GMT
I am hoping to get the unit to Gill the Sunday after next. I am also more hopeful that the rotor isn't damaged. I have been learning a bit from another gentleman, that John has rebuilt a DR3 for, about the cap and transformer. He advices a 10 mfd oil filled cap and leaving the transformer alone. I'll vote for that, since I don't really understand how to determine a substitution.
I am wondering if a DR on 134a will make all the boiling noises that I know and love.
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Post by coldspaces on Mar 8, 2014 6:06:27 GMT
I am hoping to get the unit to Gill the Sunday after next. I am also more hopeful that the rotor isn't damaged. I have been learning a bit from another gentleman, that John has rebuilt a DR3 for, about the cap and transformer. He advices a 10 mfd oil filled cap and leaving the transformer alone. I'll vote for that, since I don't really understand how to determine a substitution. I am wondering if a DR on 134a will make all the boiling noises that I know and love. Shouldn't be a problem, when you come up you can listen to mine boil. And the relay click on and off. |
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