Mitsubishi Electric PUHY-P72THMU-A Service Handbook page 256

[ IX Troubleshooting ]
[THMU-A]
Items to be checked
[3] <P72 and P96 models>
Check whether
the inverter is
damaged.
(1) Disconnect the inverter
(No load)
output wire from the ter-
minals of the INV board
(SC-U, SC-V, SC-W).
(2) Disconnect the short-cir-
cuit connector from CN6
on the INV board.
(3) Put the outdoor unit into
operation.
Check the inverter output
voltage after the inverter
output frequency has sta-
bilized.
<P120 model>
(1) Disconnect the inverter
output wire from the out-
put terminals (U, V, W) of
the IPM.
(2) Turn on SW1-1 on the
INV board.
(3) Put the outdoor unit into
operation.
[4] Put the outdoor unit into oper-
Check whether ation.
the inverter is Check the inverter output volt-
damaged. age after the inverter output
(During com- frequency has stabilized.
pressor opera-
tion)
[5] Remove the wire for the out-
Check the fan door fan motor, and check the
motor ground fan motor megger and the
fault or the winding resistance.
winding.
[6] (1)
Check the fan output wir-
Check the FAN ing.
board failure.
(2) Check the connector CN-
VDC connection.
(3) Check the FAN board
failure.
HWE08040
Phenomena
1) Inverter-related problems are de-
tected.
2) Inverter voltage is not output.
3) There is an voltage imbalance be-
tween the wires.
Greater than 5% imbalance or 5V
4) There is no voltage imbalance be-
tween the wires.
1) Inverter-related problems are de-
tected.
2) Inverter voltage is not output.
3) There is an voltage imbalance be-
tween the wires.
Greater than 5% imbalance or 5V
4) There is no voltage imbalance be-
tween the wires.
1) There is an voltage imbalance be-
tween the wires.
Greater than 5% imbalance or 5V
1) Fan motor megger failure
Failure when the megger is 1Mohm
or less.
2) Fan motor disconnection
Standard: The winding resistance
is approximately several ohm.
(It varies depending on the temper-
ature, or while the inner thermo is
operating, it will be ohm)
Connector contact failure
Board side (CNINV)
Fan motor side
Cnnector contact failure
1) The voltage imbalance among
each motor wiring during operation
(The voltage imbalance is greater
than the larger of the values repre-
sented by 5% or 5 V.)
2) The same error occurs even after
the operation is restarted.
- 247 -
Remedy
Connect the short-circuit con-
nector to CN6, and go to sec-
tion [1].
Replace the INV board.
Replace the INV board.
Normal
*Reconnect the short-circuit
connector to CN6 after check-
ing the voltage.
Turn off SW1-1 and go to [1]
Check the connection be-
tween the IPM and the
CNIPM on the INV board.
Replace the IPM.
If the problem persists, re-
place the INV board.
Replace the IPM.
If the problem persists, re-
place the INV board.
Normal
*Turn off SW1-1
<P72 and P96 models>
Replace the INV board.
<P120 model>
Replace the IPM.
If the problem persists, re-
place the INV board.
If the problem persists after
replacing the above parts, go
to section [2].
Replace the fan motor.
Connect the connector.
Connect the connector.
Replace the FAN board.
GB