Mitsubishi Electric EHGT17D-YM9ED Service Manual page 49

Error Codes (Controller circuit board)
Code Error
None ―
63H connector open
Abnormal if 63H connector circuit is open
for 3 minutes continuously after power
F5
supply.
(5201)
63H: High pressure switch
High pressure (High pressure switch
63H operated)
Abnormal if high pressure switch 63H
operated (4.15 MPa) during compressor
operation.
U1
63H: High pressure switch
(1302)
High discharge temperature
(1) Abnormal if TH4 exceeds 125°C or
110°C continuously for 5 minutes.
(2) Abnormal if discharge superheat
(Heating: TH4−T63HS) exceeds 70°C
continuously for 10 minutes.
TH4: Thermistor <Discharge>
U2
High comp. surface temperature
(1102)
Abnormal if TH33 exceeds 125°C.
In the case of high comp. surface tempera-
ture error, compressor does not restart
unless the thermistor (TH33) becomes less
than 95°C.
TH33: Thermistor <Comp. surface>
Open/short circuit of heat pump unit
temperature thermistor (TH4, TH33)
Abnormal if open (3°C or less) or short (217°C
or more) is detected during compressor
operation.
U3
(Detection is inoperative for 10 minutes
(5104)
of compressor starting process and for 10
minutes after and during defrosting.)
TH4: Thermistor <Discharge>
TH33: Thermistor <Comp. surface>
OCH722A
Cause
1. No voltage is supplied to terminal block (TB1) of
heat pump unit.
a) Power supply breaker is turned off.
b) Contact failure or disconnection of power sup-
ply terminal
c) Open phase (L or N phase)
2. Electric power is not charged to power supply
terminal of power circuit board.
a) Contact failure of power supply terminal
b) Open phase on the power circuit board
3. Electric power is not supplied to controller circuit
board.
a) Disconnection of connector (CNDC)
4. Disconnection of reactor (ACL)
5. Disconnection of noise filter circuit board or parts
failure in noise filter circuit board
6. Defective power circuit board
7. Defective controller circuit board
8. Brine pump manual operation
9. Disconnection of wire between UNIT SIDE and
MODULE SIDE.
10. Wrong thermistor position
1. Disconnection or contact failure of 63H connec-
tor on controller circuit board.
2. Disconnection or contact failure of 63H
3. 63H is working due to defective parts.
4. Defective controller circuit board
1. Clogged or broken pipe
2. Locked brine pump
3. Malfunction of brine pump
4. Short cycle of refrigerant or brine circuit
5. Dirt of brine circuit heat exchanger
6. Decreased brine flow rate
7. Disconnection or contact failure of connector
(63H) on controller circuit board
8. Disconnection or contact failure of 63H connec-
tion
9. Defective controller circuit board
10. Defective action of linear expansion valve
11. Malfunction of brine pump driving circuit
1. Overheated compressor operation caused by
shortage of refrigerant
2. Defective thermistor
3. Defective controller circuit board
4. Defective action of linear expansion valve
5. Clogging with foreign objects in refrigerant circuit
Note:
Clogging occur in the parts which become below
freezing point when water enters in refrigerant
circuit.
6. In the case of the unit does not restart:
Detection temp. of thermistor (TH33) ] 95°C
1. Disconnection or contact failure of connectors
(TH4, TH33) on the controller circuit board
2. Defective thermistor
3. Defective controller circuit board
49
Action
1. Check following items.
a) Power supply breaker
b) Connection of power supply terminal block (TB1)
c) Connection of power supply terminal block (TB1)
2. Check following items.
a) Connection of power supply terminal block (TB1)
b) Connection of terminal on power circuit board
Check connection of the connector LI or NI.
3. Check connection of the connector (CNDC) on the
controller circuit board.
Check connection of the connector, CNDC on the
noise filter.
4. Check connection of reactor. (ACL)
5. a) Check connection of noise filter circuit board.
b) Replace noise filter circuit board.
6. Replace power circuit board.
7. Replace controller circuit board (When items
above are checked but the units cannot be re-
paired).
8. Check DIP SW6-3 and turn it OFF.
9. Refer to 'How to remove the module'. Check
connection of the wire between UNIT SIDE and
MODULE SIDE.
10. Check thermistor position and change to correct
position.
1. Check connection of 63H connector on controller
circuit board.
2. Check the 63H side of connecting wire.
3. Check continuity by tester.
Replace the parts if the parts are defective.
4. Replace controller circuit board.
1. Check piping and repair defect.
2. to 5.
Check heat pump unit and repair defect.
6. Check the brine flow rate.
7. to 9.
Turn the power off and check F5 is displayed
when the power is turned again.
10. Check linear expansion valve.
11. Replace controller circuit board.
1. Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
2., 3.
Turn the power off and check if U3 is displayed
when the power is turned on again.
When U3 is displayed, refer to 'Judgment and ac-
tion' for U3.
4. Check linear expansion valve.
5. After recovering refrigerant, remove water from
entire refrigerant circuit under vacuum more than
1 hour.
1. Check connection of connector (TH4, TH33) on the
controller circuit board.
Check breaking of the lead wire for TH4, TH33.
2. Check resistance value of TH4, TH33 or tempera-
ture by microprocessor.
3. Replace controller circuit board.