Service Manual

8. Troubleshooting
188
SMGB0079 rev.0 - 01/2013
Phenomenon Cause Check item
Action
(Turn OFF the main switch)
Insufcient cooling
process
Indoor cool load is greater than the cooling capac-
ity
Calculate the cool load Use a bigger unit
Excessively low suction
pressure
Gas leakage or short-
age of refrigerant
Measure superheat
Correctly charge the refrigerant
after repairing the gas leakage
Excessively small
diameter tube or long
piping
Measure and check the eld-
supplied pipes
Use the correct pipes
Incorrect activation of
the check valve of the
outdoor unit
Check whether or not the temp.
difference exists before/after
the check valve
Replace the check valve for the
outdoor unit
Failure or malfunction
of the expansion valve
Check for clogging Remove the clogging
Check the connection cord and
the connector
Replace the connector
Is there an operation sound
from the coil?
Replace the coil
Is the thermistor on the com-
pressor normal?
Replace the thermistor
Is the thermistor installed cor-
rectly on compressor?
Correctly install the thermistor
Clogged strainer in the
indoor unit; clogging at
the low pressure piping
Check the temp. difference at
the inlet and the outlet of the
strainer
Replace the strainer in the
indoor unit
Clogging at the low
pressure piping
Check the temp. difference Remove the clogging
Insufcient air ow to
the indoor unit heat
exchanger
Check for clogged air lter Clean the air lter
Check for an obstacle at the
inlet or the outlet
Remove the obstacles
Excessively low air
temp. to the indoor unit
heat exchanger
Insufcient speed of the indoor
unit fan motor?
Replace the fan motor
Short-circuited indoor unit air?
Remove the cause of the short-
circuited air