Specifications

1. Verify the refrigerant charge.
•Remove the charge and weigh it back in.
•Make sure the system has the refrigerant
amount specified for the line length (see
Service Manual).
2. Measure for temperature differences across
evaporator.
•Set unit operation to cooling and change
temperature set point to lowest degree
available, or switch system to emergency
COOL mode.
•Change fan operation to high speed.
• Run system for five minutes, and then measure
both the entering and leaving air temperatures
with a thermometer.
•The temperature differential should be around
20° F to 23° F (see Service Manual).
Assuming you have verified the charge, a difference
of less than 20° F means the system is restricted.
A difference of 23° F or more usually means low
air flow, often because dirt has built up on the
fan blades. Clean the fan and coil and check
temperatures again.
Note: When testing the system, remember to
change the fan operation to high speed and verify
that the unit is charged with the proper amount
of refrigerant.
How to Check for Refrigerant Restriction:
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