Service Manual

7
With the design of the new enhanced cabinet and low side design, checking the evaporator
plate in the above description has become somewhat complicated.
As an alternative to the above method, we offer two varying methods.
1) The first method is similar to the above. However, with the compressor running, the
interior evaporator cover must be removed, the evaporator fan disconnected, and
the door left open for observation for 10 minutes. The evaporator plate should show
a slight full frost pattern similar to the photo below with a typical factory refrigerant
charge as stamped on the manufacturer’s serial plate.
2) The second method which is somewhat unproven at this time is to measure the
temperature of the filter drier. A rule of thumb is that the drier temperature should
be approximately 90° F at a 70° F ambient temperature.
 AGA Marvel does not recommend taking system pressures and does not have a
reference table to use for diagnosing or charging.
“Checking the evaporator frost pattern is a good way to quickly diagnose simple sealed system
problems. This can be done by allowing the unit to run (at least 10 minutes) with the door open for at
least 5 minutes. This will help speed up the normal frosting of the evaporator plate. By visually
inspecting the evaporator and feeling it with your hands, you will see and feel as the frost pattern builds
across the plate. The frost pattern should cover a majority of the evaporator plate. This will ensure the
system has been charged correctly and does not have a leak, partial restriction, or is undercharged. A
partial frost pattern may lead to excessive run times, reduced performance and efficiency.”