This task covers:
Refrigeration Unit Service Tool Kit
(1) Check that unit HIGH and LOW PRESSURE CHARGING VALVES are open and all four service
manifold valves are closed.
(2) Both gages should read the same. Check the reading with the appropriate column in table 5-2. If the
system is even partially charged, the pressure should be approximately equal to that shown in the table
for the appropriate ambient temperature. If the pressure is considerably less than shown in the table,
the system does not contain enough refrigerant to continue the pressure check; proceed directly to
(3) Turn air conditioner on and operate in COOL mode with potentiometer TEMPERATURE control set at
maximum COOL position for five minutes.
(4) With unit operating, allow gages to stabilize. Take readings of the two gages. (See table 5-3.)
(a) If discharge and suction pressures are at, or near, the same value, a pressure equalizer solenoid
(b) It discharge pressure is low and suction pressure is normal, a low refrigerant charge is indicated.
(c) If discharge pressure is normal and suction pressure is either high or low, failure or maladjustment of
the expansion valve is indicated.
(d) If ice forms on evaporator coil, or evaporator coil does not cool during operation, failure or malfunction
(e) If discharge pressure is high and suction pressure is normal, refrigerant overcharge is indicated.
(5) When pressure tests are completed, turn unit off and proceed with any maintenance action indicated.
(6) Turn rotary MODE selector switch to OFF/RESET.