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16
EN
V2-C5-15-03-v1
Troubleshooting of heat pump
No.
Message
Probable cause
Possible solution
in heating mode
Possible solution
in cooling mode
A1
Compressor failure
Compressor motor,
drive or control system
failure.
See operation manual (p. 94).
A2
Overload protection
activated.
The compressor has operated in critical conditions or there is insuf-
ficient refrigerant amount in heat pump hydraulic circuit. Check the
working conditions and make sure they are in limits. Low refrigerant
level see item C8.
B1
High pressure on com-
pressor
Low air flow.
Increase supply air flow.
Increase extracted air flow.
B2
Condenser obstructed.
Clean condenser surface.
B3
High pressure trans-
ducer failure.
Check pressure in heat pump system with manometers. If pressure
reading does not match, check cable connection or replace transmit-
ter if necessary.
B4
Incondensable gas in
heat pump hydraulic
circuit.
Recharge circuit after having drained and evacuated it.
B5
Refrigerant filter
clogged.
Check and replace if necessary.
B6
Excessive refrigerant
charge.
Discharge the excess gas.
B7
Expansion valve does
not work properly.
Check and replace if necessary.
B8
Liquid receiver rotalock
valve is closed.
Check and open.
C1
Low pressure on
compressor
Low air flow.
Increase supply air flow
.
Increase extracted air flow.
C2
Frosted evaporator.
See item D1.
C3
Low pressure trans-
ducer failure.
Check pressure in heat pump system with manometers. If pressure
reading does not match, check cable connection or replace transmit-
ter if necessary.
C4
Evaporator obstructed.
Clean evaporator surface.
C5
Expansion valve does
not work properly.
Check and replace if necessary.
C6
Refrigerant filter
clogged.
Check and replace if necessary.
C7
Moisture in heat pump
hydraulic circuit.
Replace filter and dry out system.
C8
Low level of refrigerant.
Check circuit with leak detector. Repair, evacuate and refill circuit
with refrigerant.
C9
Refrigerant filter
clogged.
Replace filter.
D1
Evaporator is icing
Defrost solenoid valve
does not open.
Check solenoid valve coil. Check
solenoid valve and replace if
necessary.
D2
Air pressure transducer
failure.
Check air pressure measure-
ment tubes. Replace air pres-
sure transducer if necessary.
D3
Evaporator tray heating
element failure.
Check and replace if necessary.
E1
Heat pump does not
start
Too low outdoor tem-
perature.
Heat pump will start operating
when the outside air temperature
will be above -15 °C (approxi-
mately).
E2
Low supply or/and
exhaust air volume.
Set the air flow more than 40
percent of the nominal air flow.
