Daikin ALTHERMA HT ERSQ 011 AA Service Manual page 214

Troubleshooting by Indication on the Remote Controller
3.53 "U0 " Low Pressure Drop Due to Refrigerant Shortage or
Electronic Expansion Valve Failure
U0
Remote Control
Display
Applicable Models ER*Q 011~016*
Method of
Short of gas malfunction is detected by discharge pipe temperature thermistor and low pressure saturation
Malfunction temperature.
Detection
Malfunction Microcomputer judge and detect if the system is short of refrigerant.
Malfunction is not decided while the unit operation is continued.
Decision Conditions
 Out of gas or refrigerant system clogging (incorrect piping)
Supposed Causes
 Defect of pressure sensor
 Defect of outdoor unit PC board (A1P)
 Defect of thermistor R3T
204
ESIE09-08A
Troubleshooting