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Changing a Cooling unit -
Dometic Instructions
Thank you for considering an RV Ice Box cooling unit
Re-Manufactured Cooling Units for Dometic and Norcold RV Refrigerators
All Units include a two-year warranty
THREE (3) YEAR LIMITED WARRANTY
Pulling the Refrigerator. The first step in changing a cooling unit is to
pull the refrigerator from its cabinet in the RV. Start by turning off the
propane at the main bottle(s) and burning off any residual in the lines at a
stovetop burner. Next, from the outside access door for the refrigerator,
disconnect the propane line to the refrigerator, unplug the 120 volt cord, and
disconnect the 12 volt wiring to the refrigerator. Tape up the ends of the 12
volt wires with electrical tape to prevent sparking. While back there locate two
screws that are usually at the bottom outside edges of the refrigerator,
securing it to the cabinet floor, and remove them.
Next remove the refrigerator doors. After that, most models have four to six
mounting screws on the face of the refrigerator, usually covered with plastic
plugs. See graphic below. These need to be removed. Look for any other fasteners
that might prevent removal of the refrigerator. Next, inside the RV, underneath
the refrigerator, there is usually a bead of silicone that needs to be cut with
a razor knife. The refrigerator should then be free and slid into the RV. If it
doesn't move, look around for something else holding the refrigerator in.
Sometimes RV manufacturers create their own ways of securing the refrigerator.
If possible, take the refrigerator out of the RV to a larger work area.
Removing the Cooling Unit
Begin by removing the aluminum freezer plate
from the freezer. These are usually held in by a few bolts or screws. Remove the
fasteners and pull off the freezer plate. This will expose pipes from the
cooling unit protruding into the freezer. In the lower box, on the aluminum
fins, there may be one or two capillary tubes from thermostats held in place by
a small plate. A capillary tube is the sensor from a thermostat and resembles a
wire. The plate needs to be loosened and the capillary(ies) removed from the
fins. Not all models have capillary tubes connected to the fins, so if they are
not there, don't worry about it. Also, some of the newer models have a
thermistor, instead of a capillary tube, clipped to the fins. The thermistor is
a small plastic thing about the size of a quarter, but thicker. It has two wires
running from it. Just pull it off and let it hang. The fins will stay with the
cooling unit until it is removed.
Once the work inside the refrigerator is done, lay the refrigerator on it's
face. Depending on the circumstance, it may be necessary to lay an old blanket
down to protect the face of the refrigerator. The cooling unit is the set of
coils on the back of the refrigerator, extending from the top to the bottom.
This is what we're after. Obvious parts such as burner assemblies, heat elements
etc. need to be removed from the unit. The RM760, RM761, RM763, RM1300, RM1301,
RM1302, and RM1303 have a cam holding the burner assembly to the bottom of the
cooling unit chimney. Locate the cam and pull it's lever towards you (see
below). This will allow the burner to drop down. Anything else in the way of
pulling the cooling unit needs to be removed.
There are handful of obvious screws holding the cooling unit to the
refrigerator that need to be removed. See graphic below. Some models, such as
the RM763 and RM1303, also have two hidden screws near the "big tube" at the
bottom of the backing, underneath the backing. Some later models (RM3600,
RM3800) may or may not have these screws. The RM760, RM761, RM763, RM1300,
RM1301, RM1302, and RM1303 models have the thermostat capillary tube inserted
into a tube that is a part of the cooling unit. See graphic below. This needs to
be pulled out. A steady pressure on the capillary tube will usually break it
free for removal. Sometimes, due to corrosion, the end of the capillary tube
will break off. If this happens, you will need to replace the thermostat. If
you're concerned about the capillary tube being stuck and breaking, standing the
refrigerator on its head and squirting something like WD-40 down the thermostat
tube of the cooling unit may help. If you do this, you need to let the WD-40 set
for a few hours before pulling the capillary tube.
Once all fasteners have been removed, the cooling unit is ready to pull. A
pry bar under the "big tube", as in the graphic below, will usually do the job.
The "big tube" is the only pipe that should be pried on. Since you will be
prying against the refrigerator body, a board or some other protection is
necessary between the pry bar and the refrigerator to prevent poking a hole in
the box. This is usually enough to pull a cooling unit, but not always. If yours
is stubborn, peel up the edges of the aluminum backing paper to expose a line
between the foam of the cooling unit head and the insulating foam of the
refrigerator box. If the cooling unit has already been replaced before, the
backing may be a piece of sheet metal instead of paper. With some effort, the
sheet metal can be removed and slid out from the cooling unit. Running a large
knife around the line between the two foams of the cooling unit and box (about
4" deep) and then prying as before will remove the more difficult units. If
you're still having problems, go back and be sure you have removed all
fasteners. Once the cooling unit is out, remove the screws from the aluminum
fins and pry them off the cooling unit head. Pull the baffle from the cooling
unit chimney and remove any other parts (except the insulation pack) from the
unit. These parts will be transferred to the replacement cooling unit.
Not transferring the baffle from the old unit to
the new one is the most common mistake made by installers. Be sure you are
familiar with what the baffle is. Normally, the only thing left on the old
cooling unit after it has been changed, is the insulation pack. You're now done
with the removal. Note: there is usually a clear plastic sheeting between the
foam of the cooling unit head and the foam of the box. This was there to keep
the two foams separated when the foam of the cooling unit was poured while the
cooling unit was already in place. This plastic can be discarded. This is also
why there can be a little difference between the foam heads of cooling units.
Installation
Inspect the rebuilt unit that you are going to install for
freight damage. One common problem that is easier to fix before installation
rather than after is a bent freezer coil. The freezer coil should be
perpendicular to the back of the cooling unit. If the coil is bent you can use a
bar, as in the graphic below, to level the freezer coil.
The key to a successful cooling unit installation is a snug fit between the
cooling unit head (foam block) and the box, with the head all the way into the
cavity of the refrigerator and no air leaks. By all the way into the cavity,
we're referring to the face of the foam block. Sometimes, because of
refrigerator variations, the head is thicker than the cavity and protrudes a
little out the back. This is OK, along as the front of the head is flush with
the inside of the refrigerator. The part sticking out will be taken care of
later.
In the graphics below, the
 is
a metal to metal contact point that requires thermal mastic. The
 refers
to a fit point -- a point where the cooling unit has to make good, snug contact
with the refrigerator box.
The first step in installing a cooling unit is to apply thermal mastic to the
coils of the cooling unit that contact the aluminum fins of the refrigerator.
Before doing that, be sure the cooling unit pipes are making contact with the
fins, without the foam of the head preventing that contact. Sometimes the foam
needs to be grated down to allow this contact. See graphic below. After the
mastic has been applied, install the aluminum fins to the cooling unit. Be sure
to well tighten the screws that mount the fins. There are brackets for the
screws below the surface of the foam. On our rebuilt units the holes in these
brackets are drilled a size too small, so that your screws will get a good bite.
You should see the screws slightly pull the area around them inward. Getting the
fins on tight with mastic is critical. Failure to do so will cause cooling
problems in the lower box. You should also put mastic on the freezer coils,
before installing the freezer plate later.
Next, before sealing the edges of the foam block of the cooling unit and
permanently installing it into the refrigerator, it's a good idea to place the
cooling unit into the refrigerator to see how well it fits. Sometimes the foam
block is too big and needs to be trimmed. Don't get carried away with trimming.
A rasp works well. Often, after a test fit, you can see marks on the side of the
foam that indicate a high spot. Once comfortable with the fit of the cooling
unit, put about a half inch bead of "Silicone or Latex Caulk" around the edge of
the foam block and place the cooling unit into the refrigerator.
Next, install the mounting screws for the cooling unit. It is important that
the two top mounting screws line up with their corresponding holes in the
refrigerator. Although all the mounting holes of the cooling unit should line up
with the refrigerator, the top two are the most important because they set the
angle of the condenser. Also, it is not unusual for this part of the cooling
unit to get bent in shipping. If the cooling unit is bent in such a way, it can
usually be straightened by running a pry bar through the top pipe of the cooling
unit and over the edge of the refrigerator box and prying upward. Failure to get
the top two screws in their respective holes may cause the cooling unit not to
work.
The lower half of the cooling unit should be fastened to the refrigerator in
such a way that the boiler (the pipe inside the insulation pack) is parallel to
the side of the refrigerator. Normally lining up the cooling unit holes with the
holes of the refrigerator accomplishes this. But if it doesn't, it is
permissible to move the lower half of the cooling unit (after the top half has
been secured) so that the boiler is parallel to the edge of the refrigerator and
start new mounting holes. Once the cooling unit body is fastened down, use
screws and duct tape (I prefer aluminum foil tape) to secure the sheet metal
backing of the cooling unit in such a way that it is virtually impossible for
air to get into the refrigerator from the back. If the head (foam block)
protrudes above the surface of the refrigerator box, this is the time to take
care of it. Usually a few sheet metal screws along the loose edges of the
sheet metal will solve the problem. If the screws don't catch, a good tape job
along the edges will suffice.
Install all the peripherals that you had removed earlier (heat elements,
baffle, burners etc.). If the mounting bracket on the cooling unit for the
burner is like the one in the graphic below, it is very important that you use
the original machine screws that were removed from these holes when replacing
the burner. Using other screws may actually "drill" a hole into the cooling
unit, discharging the coolant. In other words, making a dangerous, nasty mess
and ruining the cooling unit.
Once everything on the back of the cooling unit has been installed, set the
refrigerator upright. Put mastic on the freezer coils in the freezer and install
the freezer plate. Reinstall the thermostat capillary tube(s) or thermistor to
the fins in the lower box, if appropriate.
Installing the Refrigerator Install the refrigerator back into the RV and
make the necessary connections for the electrical and gas. Test for propane
leaks at the connections you have made and all gas parts on the refrigerator.
The refrigerator should set upright about 30 minutes before being put into
operation. If possible, test the refrigerator on 120 volt first, only because
there are less variables on the electrical side than on propane. You should see
signs of cooling in the freezer in an hour or hour and a half, and an empty box
should come down to temperature in six to eight hours.
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