Refrigerator Overview - Dometic RM2620 Installation And Operating Instructions Manual

ABSORPTION COOLING SYSTEM
In an absorption refrigerator system, ammonia is liquefied in
the finned condenser coil at the top rear of the refrigerator.
The liquid ammonia then flows into the evaporator (inside the
freezer section) and is exposed to a circulating flow of hydro-
gen gas, which causes the ammonia to evaporate, creating a
cold condition in the freezer.
When starting this refrigerator for the very first time,
the cooling cycle may require up to four hours of run-
ning time before the cooling unit is fully operational.
The tubing in the evaporator section is specifically sloped to
provide a continuous movement of liquid ammonia, flowing
downward by gravity through this section.
Sodium chromate is used for corrosion protection (less than 2
weight % of the coolant).
Leveling the refrigerator
Leveling is one of the requirements for proper operation with
absorption refrigerators. to ensure proper leveling the vehicle
needs to be leveled only so it is comfortable to live in (no no-
ticeable sloping of floor or walls).
Any time the vehicle is parked for several hours with the refrig-
erator operating, the vehicle should be leveled to prevent this
loss of cooling.
If the refrigerator is operated when it is not level and the
vehicle is not moving, liquid ammonia will accumulate in sec-
tions of the evaporator tubing. This will slow the circulation
of hydrogen and ammonia gas, or in severe cases, completely
block it, resulting in a loss of cooling.
When the vehicle is moving, the leveling is not critical, as the
rolling and pitching movement of the vehicle will pass to either
side of level, keeping the liquid ammonia from accumulating in
the evaporator tubing.
THERMOSTAT
The thermostat controls both the gas and electric operation,
thereby eliminating the necessity of resetting each time a dif-
ferent energy source is employed. After the initial start-up, the
thermostat should be adjusted to the desired temperature set-
ting, usually about mid setting.

REFRIGERATOR OVERVIEW

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CONTROL SYSTEM
The refrigerator is equipped with a semi Automatic Energy
Selector (AMES) control system, which can be set to auto-
matically select either 120 V AC or LP gas operation (AUTO
mode), or if desired LP gas only (GAS mode). The refrigerator
controls will work down to 9.6 volt DC.
This control system contains a feature where it will continue
to operate the cooling system in the event of a failure of a ma-
jor operating component. Two different modes of operation can
occur in this category:
1) The first limp mode of operation will execute if the dis-
play module becomes non functional. The control system
will revert to full automatic operation selecting the best
energy source available with AC, GAS priority. The tem-
perature setting will be maintained at the mid position.
The power module will continually attempt to reestablish
operation of the display module.
2) The second limp mode of operation will execute when
a failure of the temperature sensing device or associated
electronic circuitry occurs. If this should happen, the
control system will operate on the energy source selected
via the control panel. The cooling unit will run continu-
ously on the selected energy source. The refrigerator will
continue to operate in this mode indefinitely or until a
new sensor is installed and the system is reset.
CLIMATE CONTROL SYSTEM
During the summer months of high temperatures and humidity,
the metal frame between the freezer and fresh food compart-
ments may have water droplets forming. The number of water
droplets will increase if the vehicle isn't air conditioned during
these months. The refrigerator comes standard with a 12 V DC
climate control that will evaporate the water droplets when they
form.
To turn on the climate control, turn the Climate control switch
to ON.
The Climate control switch
is located beneath the top
decoration panel that houses
the control panel.
The climate control can be left on continuously or used only
when temperatures require it.
NOTE! When turned on, the climate control will draw 12 V
DC power continuously. Turn it off when a charging source is
not available.