York YUHC 18, Service Manual, Page: 25 / 49

5.2 Self-diagnosis
5.2.1 Indoor unit
No. Type Contents LED Flashing Remark
1 protection Over current protection of the compressor
occurs 4 times in 1h Lamps of operation, timer,
defrosting (only fan )
flashing simultaneously at
5Hz. Whole unit is shut down.
It cannot recover unless
power is cut off
2 protection Outdoor protection (absent phrase, phrase
sequence and temperature protection) All lamps flashing at 5Hz
3 error Room temperature sensor checking channel
is abnormal Timer lamp flashing at 5Hz
4 error Evaporator sensor checking channel is
abnormal Operation lamp flashing at
5Hz
5 error Condenser sensor checking channel is
abnormal Defrosting lamp flashing at
5Hz
6 error Temperature fuse is melt(reserved) Operation lamp and timer
lamp flashing at 5Hz
Recover automatically
after errors are
eliminated(For T3
malfunction of 5HP, can”t
recover automatically)
5.2.2 LEDs for the indication of outdoor trouble(3 phase type,3.5~7HP)
Type Contents LED1 LED2 LED3
Trouble Phase sequence Flash Off Off
Trouble Lack of phase Flash Off Off
Trouble Protection of pressure Flash Flash Off
Trouble Overload of current Off Off Flash
Trouble Open-circuit and short-circuit trouble of T3 Off Flash Flash
Trouble Open-circuit and short-circuit trouble of T4 Off Flash Off
Trouble High temperature protection of condenser Flash Flash Flash