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| Norcold now on Duracool [message #137804] |
Sat, 06 August 2011 22:24  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Today I installed duracool in my original norcold fridge.
It was slowly getting worse and was never great since I got the coach in 2008. it was finally to the point where we bought ice just to keep the fridge cool enough. I know it has a slow leak, but I liked how it cooled fast when it did work a bit. I figured on Duracool, if I need an ounce or so a year its not a big deal.
I installed a duracool tap and used my duracool gauge to install the duracool. The duracool went in much slower than the A/C due to I'm guessing the small tap orifice. Using the gauge, I brought up the pressure to about 30psi. I noticed the condenser was getting warm all over vs before it only got warm at about the top 3"
However the cooling plate only gets down to 33F at the top of the freezer and 45F on the bottom of the freezer. I'm thinking that means I have overcharged? so I let some out twice, but no change.
Ideas?
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: Norcold now on Duracool [message #137817 is a reply to message #137804] |
Sun, 07 August 2011 01:03  |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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| RF_Burns wrote on Sat, 06 August 2011 20:24 |
Today I installed duracool in my original norcold fridge.
It was slowly getting worse and was never great since I got the coach in 2008. it was finally to the point where we bought ice just to keep the fridge cool enough. I know it has a slow leak, but I liked how it cooled fast when it did work a bit. I figured on Duracool, if I need an ounce or so a year its not a big deal.
I installed a duracool tap and used my duracool gauge to install the duracool. The duracool went in much slower than the A/C due to I'm guessing the small tap orifice. Using the gauge, I brought up the pressure to about 30psi. I noticed the condenser was getting warm all over vs before it only got warm at about the top 3"
However the cooling plate only gets down to 33F at the top of the freezer and 45F on the bottom of the freezer. I'm thinking that means I have overcharged? so I let some out twice, but no change.
Ideas?
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I did a test run of an old Norcold with a new 120 volt compressor last summer. I used duracold. It is tricky to get the proper charge as it is so small but I did make it run well, with low freezer temps. The problem I had was that the substitute compressor was simply too small capacity (was from a home water cooler) and ran all the time to keep the box cold.
Remember the temps and pressures for a coach AC will NOT be the same as you need for a refrigerator. The freezer evaporator temp needs to be in the range of 0 F, so the pressure will be different. As I recall, from memory, I was running a suction pressure of close to 0 psi. Actually I charged the thing by guess and by god. It did work well, other than the too small compressor.
I am thinking your original compressor, as well as having a leak, might just be worn internally, which is why you were having problems to begin with. But the fact that your condenser is now warm all over makes that a questionable statement.
Keep fiddling with the charge, but use a lower suction (low side) pressure and see how that works out. Lower suction pressure means a colder evaporator, which is what you want.
Rob Allen
former owner of '76 x-PB
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| Re: Norcold now on Duracool [message #137833 is a reply to message #137804] |
Sun, 07 August 2011 07:37 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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| RF_Burns wrote on Sat, 06 August 2011 22:24 |
Today I installed duracool in my original norcold fridge.
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Which Duracool? There are two kinds. I don't know which kind the fridge needs but it may not be the same as the Chassis AC. I suspect if you charged with the wrong one that may be the problem.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: Norcold now on Duracool [message #137871 is a reply to message #137840] |
Sun, 07 August 2011 11:11 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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Senior Member |
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| mcolie wrote on Sun, 07 August 2011 06:36 |
| midlf wrote on Sun, 07 August 2011 08:37 |
| RF_Burns wrote on Sat, 06 August 2011 22:24 |
Today I installed duracool in my original norcold fridge.
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Which Duracool? There are two kinds. I don't know which kind the fridge needs but it may not be the same as the Chassis AC. I suspect if you charged with the wrong one that may be the problem.
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Steve,
Before this all started, I talked to people at Norcold/Thetford and found out that the original charge was R-12, but they could find no record of the quantity. So, both Bruce and I are kind of flying blind on this. I made mine work and Bruce is real close.
I'm always amazed at how charge quantity sensitive these little units are.
Matt
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The original ones in the GMC's were R12. The one I changed out the compressor on was a much later one, just prior to their stoping the production I guess. It used R134a as did the little water cooler compressor I used as a substitute for the original dead swing motor compressor. I charged mine with R12a, Duracool. Again, maybe luck but I got it to cool well, right temps, etc, but the compressor ran full time, just too small for the box. I need to get looking for a slightly larger one and get back to the project. This summer I got diverted into a restoration of a 22' Argosy travel trailer, which is fun too. Keeps me occupied anyway.
Yes, Matt, the charge is really small, and really sensetive, and R12a seems to operate in a slightly different manner than the "freon" type refrigerants. The original charge was probably less than an oz of R12, and then would be a lot less with R12a, as it is considerably lighter. My guess would be half an oz, and that is hard to measure, so fiddling around adjustment is the way I did it.
Rob Allen
former owner of '76 x-PB
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| Re: Norcold now on Duracool [message #137912 is a reply to message #137911] |
Sun, 07 August 2011 17:07 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Since you are not trying not remove moisture and pull an absolute vacuum, and the amount of the charge is so small why not just use a small hand vacuum pump to remove everything that you can and then recharge it from there.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Norcold now on Duracool [message #137926 is a reply to message #137911] |
Sun, 07 August 2011 18:26 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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| RF_Burns wrote on Sun, 07 August 2011 14:52 |
Rob,
Someone had posted a small replacement compressor that was available for 49 or 69 bucks.. I can't seem to find it.
I reduced the charge a bit at a time and got the top of the cooling plate in the freezer down to 15F, but the floor of the freezer (cooling plate) was at 32F, close but no cigar.
I think its because I don't have a vacuum pump to remove all the R12. I'll have to play with it.
I found this as a possible replacement if things don't go well.. Still 92 watts though.
http://tinyurl.com/3zek8h5
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Bruce: I will find a small compressor from a junker one of these days. I am playing, and running experiments, not trying to make a unit I use...lol.
The refrigerator you found: look at the energy tag (a download) and it shows that it takes 317 kwh per year. That is 317,000 watt hours and divided by the number of hours in a year (8760) you get an average watt draw of 36.2 watts. (the 92 is running watts, but it does not run full time). It is a fairly respectable number. With the inverter loss, you probably would average in the range of 45 watts overall, about what the Norcold did when new. I prefer seeing a number of 270 kwh per year (30 watts) but you are not far off with this unit. I have found those yellow hang tag numbers to be reasonably accurate on the small refrigerators.
However, do check that the thing has the condenser coils in the back, not built into the side walls of the unit, which is real common these days. That does not work well when the refrigerator is put into a side confined space, such as the GMC.
What suction pressure did you run? As I recall, mine was close to 0 psi in order to make the evaporator at a low enough temp. I did not measure the high side, had no tap for that.
Rob Allen
former owner of '76 x-PB
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| Re: Norcold now on Duracool [message #137982 is a reply to message #137804] |
Mon, 08 August 2011 07:04 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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Rob,
I had put my Duracool gauge on and it was running just under the first mark which is 1/2 way to 25psi so i'm guessing thats 12.5psi.
I'll take it down further and see what happens.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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