- 22 -
Fig. 11 Fan Speed Control Fig. 12 Expansion Valve
Fig. 13 Liquid Filter Fig. 14 Liquid Indicator
6. Pressure, Superheat and Subcooling Readings
CAUTION:
To read properly the service valves must be in the middle positions.
Complaint Possible
Causes
1) High suction pressure and low head pressure
Zero superheat and zero subcooling
2) High suction pressure and low head pressure
Low superheat and low subcooling
3) High suction pressure and high head pressure
Low superheat and high subcooling
4) High to normal suction pressure and high head
pressure
Low subcooling
5) High suction pressure and high head pressure
Low superheat and low subcooling
6) High suction pressure and high head pressure
High superheat
7) Low suction pressure and low head pressure
High superheat and low subcooling
8) Low suction pressure and low to normal head
pressure
High superheat and high subcooling
9) Low suction pressure and low head pressure
Normal to high superheat and low subcooling
1) Compressor may be bad
2) Expansion valve opened, too
much oil
3) Overcharge
4) Non-condensable
gas
5) Air restricted, dirty condenser,
bad condenser fans
6) High cellar temperature, high
evaporator load
7) Undercharge
8)
Liquid line restricted after
receiver, solenoid valve restricted
9) Suction line restricted
