Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 1091

(5) Procedure for checking the inverter (No output is provided at the compressor (U,V and W).)
Is the
52C ON?
NO
Does the LD
1
(green) on the inverter
PCB flash?
YES
Turn OFF the power supply and pull
out the connectors Cn13 and 14
Turn ON the power supply
Does DC1.5~1.6V
appear at the connectors
CN13 an 14 on the
inverter PCB?
YES
Defective power transistor
(iii) Cooling(heating) effectiveness is low. (Check the refrigerant volume and refrigerating cycle in addition to
the following items.)
1) For low cooling effectiveness
a) Check if the protective function operates with the result that the operating frequency of the compressor goes below the
specified frequency value.
Note (1) When the current safe control and discharge temperature control are activated, the frequency is lowered.
b) Check if the operation of the indoor unit expansion valve is normal or there is no clogging.
c) Check if the anti-frost function operates.
Procedure for Checking Indoor unit Electronic Expansion Valve Operation
Check the indoor unit controller to expansion valve output according to the following procedure.
Measure the voltage value appearing at the pin on the control side of the expansion valve (SM) connector CnA (white, 6P
(5-conductor), and also the duration of voltage application.
Orange~Gray, Yellow~Gray
Red
~Gray, Black ~Gray
Notes (1) After the power supply is turned on, the voltage is about 5 V for 8 seconds, decreases momentarily, and then is kept
at about 5 V for about 7 seconds.
(2) When a measurement is made with a digital multitester, voltages of 6-3 V are output in sequence.
When the above duration and voltage value can be verified, the indoor unit controller is normal.
If the expansion valve does not operate (no operating sound is produced) though a voltage is provided, the expansion valve is
faulty.
By changing the setting of the thermostat, the expansion valve is operated in about 20 seconds. Like the above, a DC voltage
of about 5 V can be checked at the connector CnA.
2) Low heating effectiveness.
a) Check if the operating frequency of the compressor is lowered below the specified frequecny because the protective
function is activated.
Note (1) When high pressure control [63H2 ON: 2.26 open/2.84 closeMPa (23 open/29 close kgf/cm
control and discherge temperature control is exerted, the frequecny is lowered.
b) Check if the operation of the outdoor unit expansion valve is normal, or if any clogging occurs.
NO
Check the control PCB on
the outdoor unit side
Does DC280V
NO
appear at the connector
Cn on the inverter
2
PCB
Defective inverter PCB
(1)
NO
Defective inverter PCB
(2)
}
(2)
Approx DC5V for 15 seconds
Power line failure
NO
The remote controller error
code E45 is indicated
(See page 1083)
YES
Notes (1) Cn13 and Cn14 check points
Cn13-6
Cn13-10
Cn13-14
Cn14-4
Cn14-5
Cn14-6
(2) Check the wirng between the power transistor
module and inverter PCB. If it is normal,
judge that the power transistor module is
fauly.
(3) The 52C turns on, then turn off in 10 seconds.
This is repeated 3 times and E45 is indicated.
(1)
when the power supply is turned on.
FDC-HKXR
(3)
Tester bar
Voltage
+ -
Cn13-7
Cn13-11
Cn13-15
1.5~
1.6V
Cn14-1
Cn14-2
Cn14-3
2 )], current safe
1089