222
TROUBLESHOOTING
36) Inspect Refrigerant Pressure (Inspect Refrigerant Amount)
37) Inspection Check Valve (Refrigerant Pressure Increase)
NOTE) When replacing the refrigerant system parts, Refer to P221, [Technical Data When Replacing the Re-
frigerant System Parts].
38) Inspect Refrigerant High Pressure Switch
1. Check electric continuity of refrigerant high pressure switch
Check the continuity at CN30[1]-[2] on the main PCB under engine shutdown condition.
If there is no continuity or continuity breaks when the switch has an impact, there is contact failure. Replace the
switch with a new one.
2. Check operation of the refrigerant high pressure switch
During operation, select "Refrigerant high pressure 1 (code No. 40)" in the monitor mode of the board mainte-
nance functions. Then check the pressure when the refrigerant high pressure switch activates (when continuity
is lost) watching the pressure value and continuity from CN30[1]-[2] on the main PCB.
(Contact is OFF at 551 psi (3.8 MPa) or higher)
NOTE) When replacing the refrigerant system parts, Refer to P221, [Technical Data When Replacing the Re-
frigerant System Parts].
1. Operate all indoor units.
2. Measure the refrigerant pressure at the pressure
detection port provided in the engine compartment.
If the measured pressure deviates from the reference
value, there is a problem in heat exchange at the
evaporator or condenser, or in the refrigerant system.
NOTE) When replacing the refrigerant system parts,
Refer to P221, [Technical Data When Re-
placing the Refrigerant System Parts].
Reference values of refrigerant pressure
during operation
Mode
Refrigerant low
pressure
Refrigerant high
pressure
In cooling
72.5 ~ 145 psi
(0.5 ~ 1.0 MPa)
232 ~ 464 psi
(1.6 ~ 3.2 MPa)
In heating
58.0 ~ 131 psi
(0.4 ~ 0.9 MPa)
348 ~ 464 psi
(2.4 ~ 3.2 MPa)
If the check valve becomes blocked, liquid refrigerant remains
in the condenser reducing the heat dissipating area, which
increases the refrigerant pressure.
1. When refrigerant flow forward direction, measure the tempera-
ture at each end of the check valve, and check for extreme
temperature difference 9 ℉ (5 ℃ ).
2. If the temperature difference between these positions is large,
the check valve is blocked. Replace the check valve.
Temperature
difference
Check valve
[ 8 TON ] [ 15 TON ]
Refrigerant high
pressure switch 1
Refrigerant high
pressure sensor 1
Refrigerant high pressure sensor 1
Refrigerant high
pressure switch 1
Refrigerant high
pressure switch 2
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