CHUNLAN FRD50-B - Page 109

Troubleshooting
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C. Other failures
Failure Method of correction
Main control board
PCB1 not operating
Check for molten FU fuse;
Check for normal DC12V, DC12V output on main control board
7812-3 pin, and DC12V input on wire controller;
Check for normal DC5V, DC5V output at main control board 7805-3
pin, and DC5V on wire controller RG1-3;
Check crystal circuit on main control board and for normal voltage at
crystal oscillator pins of chips 1 and 2;
Check for normal resetting circuit 7042 on main control board
Remote control
failure
Check for normal remote control receiver;
Check for normal remote control transmitter;
Check for normal remote controller
Remote controller
failure
Check for normal 3V batteries;
Check crystal oscillator circuit;
Check for normal transmitter;
Check for displaced or bad contact in conducting rubber
No cooling function
Check for normal temperature sensor RT1;
Check for normal DC12V, DC5V power supply;
Check for reliable connection of output ports of compressor, ID/OD
fans;
Check for main control board damage
No heating function
Check for normal temperature sensor RT1;
Check for normal DC12V, DC5V power supply;
Check for reliable output port connection of compressor, reversing
valve, ID fans and OD fans;
Check for main control board damage
Reversing valve
failure
Check for intact connection of outdoor unit wiring terminals;
‘19’ pin output on main control board MCU chip shall be high level;
relay RL1 shall close by suction;
Check for intact reversing valve
Indoor fan failure
Check for intact connection of indoor unit wiring terminal and damage
of main control board;