
- 16 -
5. Use of the condenser fan control (if applicable for low ambient kit)
Head pressure setting: Cut in=170 psig; Cut out=120 psig; Differential=50 psig
It closes on rise of pressure. It may need to adjust the setting in the field to avoid
fan short cycle.
6. Use of the crankcase heater (if applicable for low ambient kit)
The crankcase heater is installed around the lower part of the compressor and
shall be turned on all the time. The heater is self-regulated.
7. Pressure, Superheat and Subcooling Readings
CAUTION:
THE VALVES MUST BE IN THE MIDDLE POSITIONS TO READ PROPERLY.
Complaint Possible Causes
a. High suction pressure and low head pressure
Zero superheat and zero subcooling
b. High suction pressure and low head pressure
Low superheat and low subcooling
c. High suction pressure and high head pressure
Low superheat and high subcooling
d. High to normal suction pressure and high head pressure
Low subcooling
e. High suction pressure and high head pressure
Low superheat and low subcooling
f. High suction pressure and high head pressure
High superheat
g. Low suction pressure and low head pressure
High superheat and low subcooling
h. Low suction pressure and low to normal head pressure
High superheat and high subcooling
i. Low suction pressure and low head pressure
Normal to high superheat and low subcooling
j. Low suction pressure and low head pressure
Low superheat and low subcooling
k. Low suction pressure and low to normal head pressure
High superheat and normal to high subcooling
l. Low suction pressure and normal head pressure
High superheat and normal subcooling
m. Low suction pressure and high head pressure
High superheat and high subcooling
n. Low suction pressure and high head pressure
High superheat and high subcooling
o. low to normal suction pressure and high head pressure
Normal to high superheat and high subcooling
a. Compressor may be bad
b. Expansion valve opened, too
much oil
c. Overcharge
d. Non-condensable gas
e. Air restricted, dirty condenser,
bad condenser fans
f. High room temperature, high
evaporator load
g. Undercharge
h. Liquid line restricted after
receiver, solenoid valve
restricted
i. Suction line restricted
j. Air restricted at evaporator,
evaporator iced
k. Evaporator restricted
l. Expansion valve restricted
m. Both evaporator and condenser
restricted; liquid and suction
lines connected wrong
n. Liquid line restricted before
receiver
o. Condenser restricted