Dometic and Norcold RV
Refrigeration Rebuilding Process
Thank you for considering a
NuCold cooling unit
Re-Manufactured Cooling Units for Dometic and Norcold RV Refrigerators
All Units include a two-year warranty
This is a general overview of the process by which we build our
cooling units. If this is the first time you have ever had
trouble with an ammonia cooling system, you may find this page interesting.
We will show you the parts that typically go wrong with an ammonia cooling
unit and what is unique about the way we repair them at Nucold
Refrigeration. Just follow the illustration below and it will refer to
thumbnail photos in the left margin.
first photo is showing the evaporator section of a Dometic cooling unit
that has gone bad. Usually you would not be able to see this portion
of the coil because it is embedded in urethane foam inside the
refrigerator box. We have stripped away some of the foam to show the rust
that has formed, causing the unit to leak ammonia which is usually evident
by a strong ammonia odor inside the box.
next photo shows part of an evaporator that has been patched at some time
by another re-builder. You can see the sleeve that was welded on to
cover up an area that was too rusted to repair. While this will fix
the leak in this particular spot, you can imagine that if this area has
rusted through, the other places in this evaporator are soon to follow.
Which is why at Nucold, we came up with a process of replacing the entire
evaporator section rather than trying to patch.
This photo simply shows a Dometic cooling unit that we have cut the
evaporator section from, getting it ready for the new tubing.
Our first step is bending all the pipe that will make up the replacement
evaporator. We designed all our evaporators (both Norcold and
Dometic) as one piece units with the hydrogen return tube inside the
larger 7/8" pipe. You can see it coming out the top of the larger pipe
in the photo. Then we bend the small lines that carry the liquid ammonia
from the condenser to the top of the evaporator. Then the brackets are cut,
which will pull the evaporator tight against the refrigerator fins.
This next photo shows the pieces for a Dometic RM2600 replacement
evaporator that have been laid out in a heavy steel welding fixture to be
assembled. A unique feature of the Dometic RM2600 and RM2800 series
cooling unit is the freezer bars that protrude inside the freezer
compartment. In this photo you can see the freezer bars have been
attached to the evaporator tubing.
This is a picture of a complete welded and assembled evaporator ready to
be installed in an RM2600 series cooling unit. The great thing here
is all the tubing is brand new, leaving little chance for a leak to just
"G" Next the complete evaporator section
is screwed down in a Line-Up frame the same dimensions as an actual
refrigerator box and the cooling unit is secured in place on top of
it. The line-up frame insures that each cooling unit will fit the
same in any refrigerator box.
"H" This is a
picture of a Norcold cooling unit that has just had a new evaporator
welded in. Now it is ready to be flushed out for contaminants and sent to
the charging room. One reason we flush the cooling unit is for contaminants
that can get in the tubing during the various stages of assembly, but
another and very important reason is to check the flow of certain
lines to make sure there are no restrictions. Very often we will
find a cooling unit that has had a line welded shut or just partially
welded shut at the factory. Sometimes this will stop the cooling all
together but more often it just makes the cooling unit act sluggish.
After the units are charged and ran for several hours they are sent to the
paint and foam shop. Here the entire cooling unit is primed and several
coats of enamel paint are added to give the cooling unit a new
"J" Once the paint has had time
to completely cure it is ready to have the urethane foam insulation pack
replaced. We do this by placing the cooling unit in a fiberglass
mold that was cast from and actual refrigerator box. We use a
fiberglass mold to install the insulation rather that than a refrigerator
box for two reasons. First, we ship a lot of cooling units and don't
always have the box there. Second, the reinforced fiberglass mold can
withstand a lot more pressure than the refrigerator boxes, especially the
newer models with the thinner vacuum pack insulated walls.
In this photo the new foam pack has been installed. During the foaming process, a sheet metal back is installed on the back of
the cooling unit. Once the cooling unit is installed in the
refrigerator the sheet metal back will be sealed to the back of
the refrigerator box to prevent moist air from being pulled into the
"L" Finally the finished
product. A completely re-manufactured cooling unit by Nucold
Refrigeration, Inc. We have a product that we can be proud of, and one the
customer knows will last.
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