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8 - TROUBLESHOOTING
8.1 - Alarm messages on the touchscreen
The operating state and any faults can be identified on the touchscreen using the controller descriptions (see appendix). The table
below lists general fault messages, possible causes and recommendations for rectifying the fault.
Text displayed on touchscreen
Phase monitor alarm
Alarm: evaporator flow
Fault: high pressure (pressure switch)
Low pressure fault (pressure switch)
Evaporator pump or condenser pump
overload
Compressor overload
Frost alarm
Alarm: low differential pressure
Alarm: high pressure (sensor)
Alarm: low pressure (sensor)
Sensor faulty or not connected
Compressor outside
Limits of use
In the event of a low pressure fault or an overload message, notify CARRIER customer service immediately.
8.2 - General troubleshooting
Fault
Heat pump not working
High pressure fault
Table 3
Possible cause
Phase failure in compressor
Oil temperature too high
Compressor motor too hot
Water flow rate through evaporator too low
Water flow rate through condenser too low
Refrigerant loss source water temperature too
low
Motor overload relay responded
Motor overload relay or soft starter responded
Water flow rate too low; source water
temperature too low
High pressure too low; source water
temperature too low
Water flow rate through condenser too low
Refrigerant loss
Sensor failure or broken lead; the affected
sensor is identified in the alarm message text or
in the controller description (inputs/outputs)
Inlet or outlet temperatures at evaporator or
condenser outside permissible range
Table 4
Possible cause
Mains isolator in OFF position
Faulty fuse
Faulty LV HRC
Power cable break
Power failure
Energy transfer not ensured
Heating circuits excessively restricted
one or more circulation pumps are not pumping
Speed (output stage) of heating circulation
pump too low or heat pump is too large
Air in heating circuit
Non-return valve stays shut
with optional external DHW heating:
- Heat exchanger too small
- Heat exchanger scaled up or silted up
High pressure switch incorrectly set
Loose terminal connections
Troubleshooting
Check power supply; check compressor fuses;
check soft starter; check oil level
Check evaporator pump, clean water filter
Check condenser pump
Contact refrigeration engineer;
Contact CARRIER
Check source energy pump or condenser pump;
check motor overload relay
Check power supply; check compressor
terminals and check motor overload relay
Check water flow rate and increase if necessary;
determine source water temperature
Contact refrigeration engineer;
Contact CARRIER
Check flow rate
Contact refrigeration engineer;
Contact CARRIER
Check sensors, sensor leads and terminals
Contact refrigeration engineer;
Contact CARRIER
Troubleshooting
Switch on
Correct fault; replace fuse
Correct fault; replace LV HRC
Correct fault; switch on
Heat pump restarts after expiry of the preheating
phase (point 3)
Open shut-off valves
Re-establish function
Increase pump speed (stepper switch), flow/
return spread ∆t = 5 K
Vent heating circuit
loosen, replace
Enlarge
Notify customer service
Clean, descale
Correct the setting
Establish firm terminal connections
19
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