TM 9-4120-403-14
High suction pressure - See (4) below.
Fan motor not operating. (See para 4-57.)
Condenser fan loose on shaft. (See para 4-56.)
Too much oil in refrigerant system. (See para 5-24.)
(2) Discharge pressure too low.
Possible causes:
Cold outside air. (See para 2-7.)
Low refrigerant charge. (See para 5-12.)
Compressor not operating. (See para 5-24.)
Problem with equalizing solenoid valve (L2). (See para 5-29.)
Problem with pressure regulating valve. (See para 5-26.)
Internal compressor damage. (See para 5-24.)
(3) Suction pressure too low.
Possible causes:
Dirty return air filter. (See para 4-23.)
Discharge or return air louvers closed. (Adjust louvers.)
Dirty evaporator coil. (See para 4-59.)
Low refrigerant charge. (See para 5-12.)
Liquid solenoid valve (L1) closed. (See para 5-29.)
Fan motor not operating. (See para 4-57.)
Evaporator fan loose on motor shaft. (See para 4-55.)
Problem with expansion valve operation. (See para 5-15.)
Expansion valve superheat too high. (See para 5-15.)
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