Checking The Inverter For Damage During Compressor Operation; Checking The Fan Motor For Ground Fault And Coil Resistance Problems; Checking The Fan Board Error Detection Circuit At No Load - Mitsubishi Electric R410A Service Handbook

[8-9 Troubleshooting Inverter Problems (TLMU) ]
8-9-5

Checking the Inverter for Damage during Compressor Operation

Items to be checked
Put the outdoor unit into operation.
Check the inverter output voltage
after the inverter output frequency
has stabilized.
8-9-6

Checking the Fan Motor for Ground Fault and Coil Resistance Problems

Items to be checked
Remove fan motor winding. Check
insulation resistance and coil resis-
tance.
8-9-7

Checking the Fan Board Error Detection Circuit at No Load

Check list
(1) Turn off breaker.
*Turn power off without fail.
(2) Remove fan board CNINV and
CNSNR connectors.
(3) Turn on breaker.
(4) Operate unit.
HWE14080
Phenomena
1) Overcurrent-related prob-
lems occur immediately af-
ter compressor startup.
(4250 Details : No.101, 102,
103, 106, 107)
2) There is a voltage imbal-
ance between the wires af-
ter the inverter output
voltage is stabilized.
Greater than the larger of
the following values: imbal-
ance of 5% or 5V
Phenomena
1) Fan motor insulation failure.
If < 1 M , Defect.
2) Fan motor wire failure.
Normal coil resistance is a few ohms.
(Changes with temperature)
Phenomenon
1) Electrical current over load error.
Check code: 4255, 4256
Detail code: 101, 104
2) Logic error
Check code: 4255, 42566
Detail code:111
3) Position error on start up
Check code: 5305, 5306
Detail code: 132
- 268 -
Remedy
a. Check items 8-9-2 through 8-9-4 for prob-
lems.
b. Check that high and low pressures are bal-
anced.
c. Check that no liquid refrigerant is present in
the compressor.
Go to "d." when the problem persists after
compressor startup was repeated several
times.
If normal operation is restored, check the belt
heater for problems.
d. Check that there is a pressure difference be-
tween high and low pressures after compres-
sor startup.
Check the high pressure with LED monitor
for changes.
Replace the compressor if there is no pres-
sure difference. (the compressor may be
locked.)
If there is a voltage imbalance
<P72, P96, P120, P144 models>
Replace the INV board.
<P168 model>
Replace the IPM.
If the problem persists, replace the INV board.
If the problem persists after replacing the above
parts, go to section 8-9-3.
Check the belt heater for problems if there is no
voltage imbalance.
When the error occurred, liquid refrigerant may
have been present in the compressor.
Remedy
Change fan motor.
Change fan motor.
Resolution
Change fan board.
Change fan board.
Normal
*After checking, return connector
CNINV & CNSNR.
GB