Mitsubishi Heavy Industries SRRM40HENG-L, Handbook, Page: 934 / 1106

FDC-HKX
932
Check how much volt is detected at the expansion
valve (SM) connector and at the pin at control side
of the connector CnA (white, 6P (5 cores)), and
measure also how many seconds the voltages are
applied.
Orange~Gray
Red~Gray
Yellow~Gray
Black~Gray
3) Inverter inspection procedures (There is no output on the compressor (U,V,W).)
(iii) When the cooling (heating) effect is felt insufficient. (Check also the refrigeration cycle for the refrigerant
quantity, etc. in addition to the following.)
1) When the cooling effect is insufficient.
•
Check if the protective function has tripped and, as a result, the compressor operation frequency has dropped below the
specified frequency
•
Does the indoor expansion valve operate properly? Is it clogged?
•
Is the frosting prevention function operated?
Check method of the indoor unit electronic expansion valve
Check the indoor controller output to the expansion valve with the following procedures.
▼ The indoor controller is normal if the seconds and
voltages as indicated at left are confirmed.
When the expansion valve does not operate while
the voltages are detected (operating sound is not
heard), the expansion valve is defective.
If the thermostat setting is changed, the expansion
valve will operate approx. 20 seconds later. Then,
approx. 5V will be confirmed at the CnA same as
above.
▼
▼
Notes (1) 5V is maintained for 8 seconds after the power on, then it drops momentarily and recovers 5V for approx. 7
seconds.
(2) When measured with a digital multi-tester, voltages of approx. 6~3V are output one after another.
Approx. DC 5V
(2)
is detected for approx.
15 seconds
(1)
at the power on.
Is 52C turned ON?
NO
NO
YES
Is LED1 (green)
on inverter PCB
flashing?
NO
YES
Is DC 540V
detected at CNW on
inverter PCB?
YES
Inspect control PCB at
outdoor side.
Remote controller trouble
code E45 on display
Error on the power
supply system
Is LED2 (red)
on inverter PCB lit or
flashing?
NO
YES
(See page 934)
Check LED2 (red) error
contents.
(See page 927)
Defective power tran-
sistor or defective in-
verter PCB
Defective inverter PCB