Carrier 42QFD048D8S Service Manual page 100

TS06-INV: Refrigerant Leakage Detection diagnosis and solution
For some models,
Description: Define the evaporator coil temperature T2 of the compressor just starts running as Tcool.
In the beginning 5 minutes after the compressor starts up, if T2 < Tcool-1°C(1.8°F) does not keep continuous 4 seconds
and compressor running frequency higher than 50Hz does not keep for 3 minutes, and this situation happens 3 times,
the LED displays the failure code and the AC turns off.
Recommended parts to prepare:
• T2 sensor
• Indoor PCB
• Additional refrigerant
Troubleshooting and
Power off, then restart the unit 2 minutes later.
Does a problem remain?
Put your hands in front of the
air blowing out from
Check system for leakages.
Check System for blockages and
clear blockages if present.
repair:
YES
indoor air outlet.
Is there cool
indoor air outlet?
NO
NO
Are any leakages
present?
NO

Check the T2 sensor.
YES
Repair the leakage and
YES
recharge the refrigerant.
Troubleshooting 
Is it securely
YES
attached?
Replace the
indoor PCB