10 Troubleshooting
10.1 Alarm
In event of alarm this is indicated in the display with the text ALARM and an alarm message, see following table.
For alarms that are not reset automatically acknowledgement is required. Acknowledge the alarm by setting the
heat pump to operating mode OFF and then back to the desired operating mode.
Message Meaning
HIGH PRESSURE ERROR Tripped high pressure switch. Compressor stopped.
LOW PRESSURE ERROR Tripped low pressure switch. Compressor stopped.
MOTOR P ERROR Deployed overload relay (overcurrent relay) compressor, deployed overload relay for outdoor
unit fan. On certain models alarms from the brine pump or soft starter can also occur. Com-
pressor stopped.
BRINE OUT Brine out is less than the set minimum temperature. Compressor stopped. No hot water pro-
duction.
BRINEFLOW LOW Flow sensor not active during last start. Compressor stopped. No hot water production.
AUX. HEATER Overheating protection deployed. No auxiliary heater.
OUTDOOR SENSOR Fault in outside sensor. When the control system calculates the heat demand, zero degrees is
used.
SUPPLY LINE SENSOR Supply line sensor error. Everything stops except the heating system’s circulation pump.
RETURN LINE SENSOR Return sensor fault. Return temperature = Supply line – 5 is used. Calculated supply tempera-
ture limited to maximum 45°C.
HOT WATER SENSOR Fault on sensor for start temperature. No hot water production.
DEFROST SENSOR Defrost sensor fault. Heating and hot water production is controlled from the outdoor sensor’s
value instead (applies to DHP-A, DHP-A Opti, DHP-AL, DHP-AL Opti).
SENSOR COOLING Sensor fault. Cooling function stops.
ERR PHASE SEQ. Alarm that indicates that there is an incorrect phase sequence to the compressor. Only display
and only the first 10 minutes.
HIGH RETURN Alarm that indicates that high return temperature prevents the compressor’s operation.
In event of alarm the heat pump will if possible supply heating to the house, primarily with the compressor, secon-
darily with the additional heater. Hot water will stop to indicate that something noteworthy has occurred.
10.2 Measurement points
1. Disconnect the relevant sensor from I/O-card/terminal block.
2. Measure the resistance for the sensor and any extension cables.
3. Then measure the sensor only.
Caution! When reading the resistance of the sensors, the sensor leads must first be disconnected from the
control equipment.
Note! To ensure the sensor value the actual temperature must be checked against the measured
resistance.
Service instructions VMGFC302 – 35
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