Carrier QHC Series Service Manual page 44

10.2.4 Refrigerant Leakage Detection diagnosis and solution(EC)
Error Code
Malfunction decision
conditions
Supposed causes
Trouble shooting:
Power off, then restart the
unit 2 minutes later.
Check cool air blowing out
from indoor air outlet
Check leakage of system
check blockIng of system and
clear the blocking
EC
Define the evaporator coil temp.T2 of the compressor just starts
running as Tcool.
In the beginning 5 minutes after the compressor starts up, if T2
＜Tcool－2℃ does not keep continuous 4 seconds and this
situation happens 3 times, the display area will show "EC" and
AC will turn off.
T2 sensor faulty
●
Indoor PCB faulty
●
System problems, such as leakage or blocking.
●
Yes
No
No
Yes
Check if T2 sensor
Yes
Yes
Replace indoor PCB.
Repair the leakage and
recharge the refrigerant.
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