-24-
8) If the superheat is high, check the subcooling first to see if the refrigerant charge
is sufficient. If the charge is not sufficient, add more refrigerant (Liquid must
always be charged into the hide side when the compressor runs). If the charge
is good, then increase the evaporator suction pressure by turning the hex nut
(5/16”) clockwise.
9) If the superheat is low, then decrease the evaporator suction pressure by turning
the hex nut
(5/16”) counter-clockwise.
Fig. 15 Expansion Valve
10) Turn both discharge and suction valves in the back positions.
11)Disconnect the manifold.
9. 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
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,
