Cooling - Mitsubishi PUZ-A18NHA6 Service Manual

<Abnormalities detected while unit is operating>
Abnormal point and detection method
Check code
High pressure (High-pressure switch
63H operated)
Abnormal if high-pressure switch 63H
worked (*) during compressor operation.
*602 PSIG [4.15 MPa]
63H: High-pressure switch
U1
(1302)
High discharge temperature
High comp. surface temperature
(1) Abnormal if discharge temperature ther-
mistor (TH32) exceeds 257˚F [125:]
or 230˚F [110:] continuously for 5 min-
utes.
Abnormal if condenser/evaporator
temperature thermistor (TH5) exceeds
104˚F [40:] during defrosting and dis-
charge temperature thermistor (TH32)
exceeds 230˚F [110:].
(2) Abnormal if discharge superheat
(Cooling: TH32−TH5
Heating: TH32−TH6) increases.
All the conditions in A or B are detected
simultaneously for 10 minutes continu-
ously after 6 minutes past from com-
pressor start-up (including the thermo-
stat indication or recovery from defrost-
ing).
U2
<Condition A>
(TH32: 1132)
• Heating mode
• W hen discharge superheat is less
than 126˚F [70:].
• W hen the TH6 temp is more than the
value obtained by TH7−9˚F [5:].
• W hen the condensing temp of TH5 is
less than 95˚F [35:].
<Condition B>
• During comp. operation (Cooling and
Heating)
• W hen discharge superheat is less
than 144˚F [80:] in cooling.
• W hen discharge super heat is less
than 162˚F [90:] in heating.
• W hen condensing temp of TH6 is
more than −40˚F [−40:] (In cooling
only).
OCH577A
Case
1 Short cycle of indoor unit
2 Clogged filter of indoor unit
3 Decreased airflow caused by
dirt of indoor fan
4 Dirt of indoor heat exchanger
5 Locked indoor fan motor
6 Malfunction of indoor fan motor
7 Defective operation of stop
valve (Not full open)
8 Clogged or broken pipe
9 Locked outdoor fan motor
0 Malfunction of outdoor fan
motor
1 Short cycle of outdoor unit
2 Dirt of outdoor heat exchanger
3 Decreased airflow caused by
defective inspection of outside
temperature thermistor
(It detects lower temperature
than actual temperature.)
4 Disconnection or contact failure
of connector (63H) on outdoor
controller board
5 Disconnection or contact failure
of 63H connection
6 Defective outdoor controller
board
7 Defective action of linear
expansion valve
8 Malfunction of fan driving circuit
1 Overheated compressor opera-
tion caused by shortage of
refrigerant
2 Defective operation of stop
valve
3 Defective thermistor
4 Defective outdoor controller
board
5 Defective action of linear
expansion valve
35
Judgment and action
1–6 C heck indoor unit and repair the defect.
7 Check if stop valve is fully open.
8 Check piping and repair the defect.
9–2 Check outdoor unit and repair the defect.
3 Check the inspected temperature of outside
temperature thermistor on LED display.
(SW2 on A-Control Service Tool : Refer
to "10-10. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
4–6 T urn the power off and check F5 is
displayed when the power is on again.
When F5 is displayed, refer to "Judgment
and action" for F5.
7 Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE
PARTS" and "10-7. HOW TO CHECK THE
COMPONENTS".
8 Replace outdoor controller board.
1 Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
2 Check if stop valve is fully open.
34 Turn the power off and check if U3 is dis-
played when the power is on again.
When U3 is displayed, refer to "Judgment
and action" for U3.
5 Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE
PARTS" and "10-7. HOW TO CHECK THE
COMPONENTS".