Viessmann VITOCAL 250-A - Page 130

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4. Replace inverter.
5. Replace compressor. Inform Viessmann Technical
Service if necessary.
F.837 Inverter electric phase connection to compressor faulty
F.837
System characteristics
Refrigerant circuit off: Inverter and compressor cannot
be switched on.
Cause
Power supply on inverter faulty, 1 or more phases of
power cable not connected
Measures
1. Check all cables connected to compressor for cor-
rect seating, contact corrosion and damage.
Replace cable if necessary.
2. Check phase connections for compressor for clock-
wise rotating field.
3. Check for correct connection of power-OFF signal:
■
Without on-site load disconnect:
Connection directly to the heat pump control unit
■
With on-site load disconnect:
Connection directly to the heat pump control unit
and to the on-site contactor for the economy tariff
■
No power-OFF signal to power supply on heat
pump control unit
4. Isolate the system from the power supply. Wait at
least 2 min. Switch on the system.
5. Replace inverter.
F.838 Inverter control faulty
F.838
System characteristics
Refrigerant circuit off: Inverter and compressor cannot
be switched on.
Cause
Control of inverter faulty
Measures
1. Isolate the system from the power supply. Wait at
least 2 min. Switch on the system.
2. Replace inverter.
F.839 Compressor blocked
F.839
System characteristics
Refrigerant circuit off: Inverter and compressor cannot
be switched on.
Cause
Compressor does not start.
Measures
1. Check all cables connected to compressor for cor-
rect seating, contact corrosion and damage.
Replace cable if necessary.
2. Check phase connections for compressor for clock-
wise rotating field. Replace phase connections if
necessary.
3. Check refrigerant lines for mechanical damage.
Refrigerant lines must be connected free of load and
torque stress.
4. Check condenser for mechanical damage. If neces-
sary, purge the condenser.
5. Check refrigerant oil for correct viscosity and
amount. Purge the refrigerant circuit.
6. Check oil sump heater on the VCMU refrigerant cir-
cuit controller: See F.1009.
Messages
Fault messages (cont.)
6218234
Diagnosis