TemperZone UC8 User Manual

Temperzone UC8 Operation, OSA models with inverter, issue 1
Page 22 of 27
11. Troubleshooting
When the UC8 controller detects a problem within the system the fault relay output (FLT) is activated.
Fault light FLT will illuminate, and a fault code is shown on the LED display.
Some faults will stop the compressor and the fan. Other faults may stop the compressor but allow the
fan to continue running. Yet other faults will be signalled but do not stop the unit from operating.
If a serious fault repeatedly stops the unit it may be locked-out. A locked unit will not run the
compressor and the fan. To unlock the unit cycle mains power to the unit off and on again,
alternatively a unit can be unlocked via Modbus RTU serial communications.
If a unit locks out three times successively without completing a successful cooling or heating cycle,
then the unit will be locked out and can only be unlocked by pressing the UC8 pushbutton.
11.1. Fault codes
Display
Meaning
Possible causes
LP
Low pressure protection is active
Low refrigerant charge (gas leak)
Pressure transducer fault
EEV malfunction or disconnected
Indoor fan or controller malfunction
HP
High pressure protection is active
No water flow (cooling mode)
Pressure transducer fault
EEV malfunction or disconnected
Indoor fan or controller malfunction
OL
Overload protection (input IN#2 is open
circuit)
Check overload switches (if used)
FROSt
Indoor coil frost protection is active
Insufficient airflow (e.g. a blocked air filter)
Indoor fan malfunction
HI-t
High temperature protection is active
Insufficient airflow (e.g. a blocked air filter)
Indoor fan malfunction
HI-SL
High suction line temperature protection
is active
Water temperature too high (heating mode)
Lo-dSH
Low discharge superheat protection active
EEV malfunction or disconnected
Incorrect EEV operating mode selected
Hi-dSH
High discharge superheat protection
active
Low refrigerant charge (gas leak)
EEV malfunction or disconnected
CRL
Low compression ratio protection
Water temperature too low or too high
CRH
High compression ratio protection
Pressure transducer fault
EEV malfunction or disconnected
Indoor fan or controller malfunction

TemperZone UC8 Specifications

General

Brand	TemperZone
Model	UC8
Category	Controller
Language	English