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Old 06-06-2013, 07:54 PM   #141
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It might cause the cycling problem he had as well. The thing could have gotten too cold and clogged then melted when it clogged and over and over again.

Perry
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Old 06-06-2013, 08:01 PM   #142
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Originally Posted by lewster View Post
I was quite dismayed to see the total lack of thermal mastic on your high temp. evaporator section! I would send this shot to Dometic and would be very interested in their response. Proper heat transfer can not happen without the right amount of thermal mastic present along the evaporator surfaces for either the freezer or fridge sections.
Lack is a relative term...By lack you mean NONE AT ALL, right? You can bet your sweet condensate drain tube that I put a boatload on that section with the new unit. I mean a lot...well, not a LOT but enough. It is a proper thermal bond in my opinion now.

OK, now I am running a bypass test in electricity and within probably 30 minutes, it seems to be getting to an equilibrium for starting. I read temperatures all across the unit. Want to know what I got??????
Of course you do!

Starting with the boiler. Ever wonder what it runs at at the heating element? This is at the boiler where thermal input occurs.


Next, boiler outlet just prior to the moisture separator section(s).


Next at the condenser inlet. Note that there is some temperature drop here. Will be interesting to see if it stays like that as I would almost expect there to be less difference between the boiler outlet temperature and the inlet to the condenser.


On to the Liquid Ammonia going into the fridge. This basically shows the temperature drop between the condenser inlet and outlet, or how much heat is being removed from the gaseous ammonia turning it into a liquid and even certainly subcooling it below state change (from gas to liquid).

And lastly, the embedded probe at the halfway point between the low temp evaporator and high temp evaporator. This was dropping within 30 minutes after first rising in temperature.


I'll go out periodically to check it all out to see what the readings are. But at this point, seems to be working just fine.
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Old 06-06-2013, 09:38 PM   #143
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After 2 hours boiler is settled in at 352 F. Boiler outlet set at 168 F, Condenser inlet set at 135. Liquid ammonia temp at 87 F. The High Temperature Evaporator is at 19 F. Fridge temp at 60 F. All is working normally for a completely unloaded fridge.
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Old 06-06-2013, 10:38 PM   #144
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Burp!?!

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Originally Posted by perryg114 View Post
Did you ever try to burp the thing (turn it upside down)?

Perry
Here is the day I burped my old unit...
http://www.airforums.com/forums/f425...tml#post710836
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Old 06-06-2013, 11:25 PM   #145
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9:00 - reefer temp empty is already 32 F.
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Old 06-07-2013, 07:34 AM   #146
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Sounds like it is fixed. Now you need to road test it.

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Old 06-07-2013, 01:29 PM   #147
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One more test to do, I am going to load it up with water bottles again and turn it on, see how it does under load with stuff not so cool in it. The "road test will be when we get on the road to International. We will be bringing a spare cooler because we are used to not having a working refrigerator.
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Old 06-08-2013, 01:29 PM   #148
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Buttercup, seems to me that a better choice would be beer bottles or cans. It's more fun to unload it that way.
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Old 06-10-2013, 09:17 PM   #149
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Alright, tonight I checked the fridge/freezer and it works on gas but not electric. I checked fuses and breakers and all looks good. The interior light on the fridge works fine. Everything else electrical seems to work fine. Any thoughts?
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Old 06-11-2013, 04:36 AM   #150
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Check continuity on the heating element, it is possible that the heater went bad. Got an ohm meter? What does that electric heater read in ohms?

Here is a heater check on an SOB trailer. The wires are disconnected from the circuit board and an ohm meter is hooked up to check the resistance, indicating a good or bad heater.
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Old 06-11-2013, 07:02 AM   #151
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Well do the math. P=IV and V=IR. I=V/R= 120/43.7=2.75A, P=(2.75A)(120V)=330W. You really need to measure current with the heater on but it 330W looks good to me.

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Old 06-11-2013, 07:36 AM   #152
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Well do the math. P=IV and V=IR. I=V/R= 120/43.7=2.75A, P=(2.75A)(120V)=330W. You really need to measure current with the heater on but it 330W looks good to me.

Perry
Measuring the current is an option, but measuring the ohms is done because it is simple and indicates if the problem is the heater itself it the circuit board. A current meter is probably going to read zero as the fridge is already not working on electricity. But it doesn't tell you if it is the heater itself or the circuit board.

An ohm check will instantly indicate the direction to look and anyway, you will have to do a resistance check the moment the current check fails.
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Old 06-11-2013, 07:53 AM   #153
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40-50 ohms is a good heater is what we have learned. This should draw around 3A when it is working. If his works on gas then the control board is working. Does the gas system use a separate board from the electric system?

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Old 06-11-2013, 12:01 PM   #154
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I hate having to rush in and out of the fridge to get something out because if the door is left open for a few seconds you loose a bunch of cold air.

Kelvin
It is not the air in the fridge that keeps the temp constant. It is the contents that keep the temp constant. Yes it is true cold air circulates inside and cools things, but the escape of some cold air is not that big a deal. Air doesn't hold many BTU'sI think it is .1% of the amount water does. Thus, taking some frozen cooler packs or ice in bottles and keeping them in the freezer and transferring them to the fridge help keep them cold when the system isn't working well. And putting them in the freezer when you start up the fridge at home before a trip will cool it down a lot faster.

When you put warm objects inside, that will do a lot more to raise temp than holding the door open for half a minute while you try to find that little jar of mustard that's hidden behind everything else.

RV fridges are very inefficient compared to residential ones, so leaving the door open for a long time is more of a problem than at home, but you have more than a few seconds.

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