AIR CONDITIONING (OPTIONAL)
1B-9
DIAGNOSIS TEST TABLE
TESTING RESULTS
POSSIBLE CAUSE
REMEDY
E
SSURE GAUGE
Pressure high
(“A” area of high side
graph)
Refrigerant overcharged
Expansion valve frozen or clogged
Clogged refrigerant passage of high side
Condenser fan malfunction
Insufficient
cooling of
Dirty or bent condenser fins
condenser
Compressor malfunction (Insufficient oil etc.)
Engine overheat
Recharge
Check expansion valve
Clean or replace
Check condenser fan
Clean or repair
Check compressor
Check engine cooling
system
HIGH PR
E
Pressure low
(“B” area of high side
graph)
Insufficient refrigerant (Insufficient charge or
leakage)
Expansion valve malfunction (valve opens too
wide)
Compressor malfunction (Insufficient
compression)
Check for leakage, repair if
necessary and recharge
Check expansion valve
Check compressor
E GAUGE
Pressure high
(“A” area of low side
graph)
Expansion valve malfunction (valve opens too
wide)
Compressor malfunction (Insufficient
compression)
Check expansion valve
Check compressor
LOW PRESSUR
E
Pressure low
(“B” area of low side
graph)
Insufficient refrigerant (Insufficient charge or
leakage)
Expansion valve malfunction (valve opens too
narrow)
Clogged refrigerant passage (crashed pipe)
Check for leakage, repair if
necessary and recharge
Check expansion valve
Repair or replace
M
OMETER A
T
T
ER DUCT
Outlet air temperature
at center duct is high
(Crossing point is in
area “A”)
Insufficient or excessive charge of refrigerant
Dirty or bent evaporator fins
Air leakage from cooling (heater) unit or air duct
Malfunctioning, switchover function of damper
in cooling (heater) unit
Compressor malfunction
Check refrigerant pressure
Clean or repair
Repair or replace
Repair or replace
Check compressor
THERM
CEN
T
Outlet air temperature
at center duct is low
(Crossing point is in
area “B”)
Insufficient air volume from center duct (Heater
blower malfunction)
Compressor malfunction
Check blower motor and
fan
Check compressor
If ambient temperature is within 30 – 35
C (86 – 95
F), it is possible to do using next page table for detail diagnosis.