Changing a Cooling Unit
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. 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 (see #2 in the diagram). Locate the cam and pull it's lever towards you . 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 (#5) in 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 (See #5 next to wooden block in the graphic below). 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 (#1) in the 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", (#7) in the graphic above, 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 sheetmetal instead of paper. With some effort, the sheetmetal 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 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. 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. We have very few issues with freight damage, but it does happen on occasion, so you need to inspect the unit for obvious signs of damage before installation. One common problem that is easier to fix before installation rather than after is a bent freezer pipe (the part the freezer shelf sets on). The freezer pipe should be perpendicular to the back of the cooling unit. If the coil is bent you can use a bar 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. 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, you are ready to apply the thermal mastic.
You must apply thermal mastic to the coils of the cooling unit that contact the aluminum fins of the refrigerator. 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. 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. The next step is to apply about a half inch bead of sealer "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 tape (I prefer aluminum foil tape) to secure the foil paper backing of the cooling unit in such a way that it is virtually impossible for air to get into the refrigerator from the back.
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.