Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 194

Error definition and error
Error Code
detection method
1302 Abnormal high
1. If the pressure of
pressure 1 3.87MPa [561psi] or
higher is detected by
(heat source
the pressure sensor
unit)
during operation (the
first detection), the heat
source unit stops once,
turns to anti-restart
mode for 3 minutes,
and restarts after 3 min-
utes automatically.
2. If the pressure of
3.87MPa [561psi] or
higher is detected by
the pressure sensor
again (the second de-
tection) within 30 min-
utes after the first stop
of the heat source unit,
the heat source unit
stops once, turns to
anti-restart mode for 3
minutes, and restarts
after 3 minutes auto-
matically.
3. If the pressure of
3.87MPa [561psi] or
higher is detected by
the pressure sensor
(the third detection)
within 30 minutes of the
second stop of the heat
source unit, the heat
source unit will make an
error stop, and the error
code "1302" will be dis-
played.
4. If the pressure of
3.87MPa [561psi] or
higher is detected more
than 30 minutes after
the stop of the heat
source unit, the detec-
tion is regarded as the
first detection, and the
operation described in
step 1 above will start.
5. For 30 minutes after the
stop of the heat source
unit, preliminary errors
will be displayed on the
LED display.
6. The heat source unit
makes an error stop im-
mediately when not
only the pressure sen-
sor but also the pres-
sure switch detects
4.15
[601
(1) LEV failure on the indoor
unit
-> Heating
(2) Heat source unit LEV1
malfunction
-> Cooling
(3) Solenoid valve malfunc-
tion (SV4a-4d)
(4) Closed ball valve
(5) Short cycle on the indoor
unit side
(6) Clogged filter on the indoor
unit
(7) Reduced air flow due to
dirty fan on the indoor unit
fan
(8) Dirty heat exchanger of the
indoor unit
(9) Indoor fan (including fan
parts) failure or motor fail-
ure
Rise in high pressure
caused by lowered con-
densing capacity in heat-
ing operation for (5) - (9).
(10) Insufficient heat source
water supply
(11) Heat source water supply
cutoff
(12) Dirty or clogged water
heat exchanger
(13) Solenoid valve (SV1)
malfunction (The by-pass
valve (SV1) can not control
rise in high pressure).
(14) Thermistor failure
(TH6).
(15) Pressure sensor failure
(16) Failure of the thermistor in-
put circuit and pressure sen-
sor input circuit on the
controller board
(17) Faulty mounting of ther-
mistor (TH6)
(18) Disconnected male con-
nector on the pressure
switch (63H) or discon-
nected wire
(19) Melted fuse (F1 or F2) on
+0,-0.15
MPa
the controller board
+0,-22
psi]
- 185 -
Cause Check method and remedy
Perform a heating operation and check
the operation.
Cooling : LEV1
Heating : LEV on the indoor unit,
SV4a-4d
Refer to the section "Troubleshooting
the LEV and solenoid valve."
Confirm that the ball valve is fully
open.
Check the indoor units for problems
and correct them, if any.
Check for dirty or clogged water heat
exchanger
Check the heat source water pump
Refer to the section on troubleshoot-
ing the solenoid valve.
Check the thermistor resistor.
Refer to the page on the troubleshoot-
ing of the high pressure sensor.
Check the temperature and the pres-
sure of the sensor with LED monitor.
Check the temperature and the pres-
sure of the sensor with LED monitor.
Check for a melted fuse.Check for
short-circuited cooling FAN (MF), 4-
way valve, or actuator like solenoid
valve.
[ IX Troubleshooting ]