Mermaid REFRIGERATION/FREEZER - Manual (Page 15)

E: System Runs, Box Temperature Too Low:
1 Thermostat setting Rotate thermostat knob to a lower
number.
2 Thermostat type Check that you are using a refrigerator
thermostat (0028) for a refrigerator
application.
3 Faulty thermostat If system is running continuously &
box temperatures are too low with
thermostat set on the lowest number,
first check for correct thermostat
connections at the Module, then remove
one connection. If compressor stops,
turn off breaker, replace connection &
then control system manually from the
breaker until the thermostat can be
replaced.
4 Holding plate over-sized If you are using a holding plate
evaporator that is over-sized for the
application, it will absorb more heat
than that which enters the box through
the insulation, & so lowers the
temperature. Experiment by covering
some of the plate surface with
insulating material until you achieve
correct box temperatures. This method
will also increase hold-over times.
5 Poor spillover system
construction
If you are running the evaporator as a
freezer, & cooling an adjoining
refrigerator compartment with some
spillover air, there must be an adequate
thermal barrier between the two, & it
must be properly sealed to prevent
unwanted air-flow. Temperatures in the
refrigerator side should be controlled
either with trial-&-error convection
holes, or a thermostatically controlled
fan. Two apertures are necessary, one
high & one low for adequate air
circulation.