Mitsubishi Heavy Industries FDE40ZMXVG Technical Manual page 171

(4) Troubleshooting at the outdoor unit
When troubleshooting the outdoor unit, firstly assess the overview of malfunction and try to presume the cause and the faulty
part by checking the error code dispalyed on the remote control and flashing pattern of indicator lamps (Red LED and Green
LED), and then proceed further inspection and remedy it.
Self-diagnosis system by microcomputor on indoor and outdoor PCB can assist to find the cause of malfunction smoothly by
making a diagnosis of not only the anomaly of microcomutor, but also the anomaly in power source system, installation space,
overload resulting from improper charging amount of refrigerant and etc.
Unless the power is reset, the error log is saved in memory and the inspection indicator lamps on outdoor PCB keep flashing
after automatical recovering from malfunction.
After automatical recovering from malfunction, if any another error mode which has a higher priority than the previous error
saved in memory occurs, it is overwritten in memory and is displayed.
[Reset of power source]
Be sure to avoid electrical shock, when replacing or checking the outdoor control PCB, because some voltage is still retained in
the electrolytic capacitor on the PCB even after shutting down the power source to the outdoor unit.
Be sure to start repairing work, after confirming that the Red LED or Green LED on the PCB has been extiguished for more
than 10 seconds after more than 3 minutes had been passed since power shut down, and reconfirming that voltage has been
discharged sufficiently by measuring the voltage (DC) between both terminals of electrolytic capacitor (C58) (Measurment
of voltage may be disturbed by the moisture-proof coating. In such case, remove the coating and measure it by taking care of
avoiding electrical shock)
(a) Module of part to be replaced for outdoor unit control
Outdoor control PCB, Inverter PCB, Temperature thermistor (of outdoor heat exchanger, discharge pipe, outdoor air,
IPM and suction pipe), Fuses (for power source and control PCB), Noise filter, Capacitor, Reactor and Transformer
(b) Replacement procedure of outdoor control PCB
Since the following precaution is the important contents for safety, be sure to observe them.
・
WARNING and CAUTION are described as follows:
WARNING
！
CAUTION
！
・ Securely replace the PCB according to this procedure.
If the PCB is incorrectly replaced, it will cause an electric shock or fire.
・ Be sure to check that the power source for the outdoor unit is turned OFF before replacing the
PCB. The PCB replacement under current-carrying will cause an electric shock or fire.
・ After finishing the PCB replacement, check that wiring is correctly connected with the PCB before
power distribution. If the PCB is incorrectly replaced, it will cause an electric shock or fire.
・ Band the wiring so as not to tense because it will cause an electric shock.
Precautions for Safety
Indicates an imminently hazardous situation which will result in death or serious
injury if proper safety procedures and instructions are not adhered to.
Indicates a potentially hazardous situation which may result in minor or moderate
injury if proper safety procedures and instructions are not adhered to.
！
！
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WARNING
CAUTION
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'15 • PAC-T-236