Troubleshooting At The Outdoor Unit - Mitsubishi Heavy Industries FDTC40ZSXVH Service Manual

(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 unit and outdoor unit PCB can assist to find the cause of malfunction
smoothly by making a diagnosis of not only the anomaly of microcomputor, 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 unit 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 unit 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 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 unit control PCB, temperature sensor (of outdoor heat exchanger, discharge pipe and outdoor air), fuse (for
control PCB) and reactor
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'18 • PAC-SM-297