Viessmann VITOCAL 151-A Installation And Service Instructions Manual page 106

Troubleshooting
Fault messages
(cont.)
Message code System characteristics
F.793 Reduced output, instantane-
ous heating water heater
F.797 Secondary pump/heating cir-
cuit pump, heating/cooling
circuit 1 is off.
No room heating, heating/
■
cooling circuit 1
No DHW heating
■
F.798 Heating circuit pump, heat-
ing/cooling circuit 2 is off.
No room heating, heating/
■
cooling circuit 2
No DHW heating
■
F.799 Secondary pump/heating cir-
cuit pump, heating/cooling
circuit 1 is off.
No room heating, heating/
■
cooling circuit 1
No DHW heating
■
F.800 Heating circuit pump, heat-
ing/cooling circuit 2 is off.
No room heating, heating/
■
cooling circuit 2
No DHW heating
■
F.801 Fault, outdoor unit, no refrig-
erant circuit reversal
F.808 The refrigerant circuit will not
start.
F.812 The refrigerant circuit will not
start.
106
Cause
Phase L3 in power supply
of instantaneous heating
water heater not present
Secondary pump/heating
circuit pump, heating/cool-
ing circuit 1 is faulty
Heating circuit pump,
heating/cooling circuit 2 is
faulty
Secondary pump/heating
circuit pump, heating/cool-
ing circuit 1 is faulty
Heating circuit pump,
heating/cooling circuit 2 is
faulty
4-way diverter valve faulty
Lower fan not running.
Upper fan not running.
Measures
Check fuse for instantaneous
■
heating water heater.
Check power supply on instanta-
■
neous heating water heater and
on connections of indoor unit.
Check power cables.
■
Check instantaneous heating wa-
■
ter heater. Replace if required.
Isolate the system from the power
supply. Restart the system.
If the fault persists, replace secon-
dary pump/heating circuit pump,
heating/cooling circuit 1.
Isolate the system from the power
supply. Restart the system.
If the fault persists, replace heating
circuit pump, heating/cooling cir-
cuit 2.
Isolate the system from the power
supply. Restart the system.
If the fault persists, replace secon-
dary pump/heating circuit pump,
heating/cooling circuit 1.
Isolate the system from the power
supply. Restart the system.
If the fault persists, replace heating
circuit pump, heating/cooling cir-
cuit 2.
Check connections on VCMU re-
■
frigerant circuit controller.
Check 4-way diverter valve
■
(function check). Replace coil if
required.
Isolate the system from the pow-
■
er supply. Restart the system.
If the fault persists, replace the 4-
way diverter valve.
Check connections on VCMU re-
■
frigerant circuit controller.
Check fan can rotate freely.
■
Check lower fan via actuator test.
■
Isolate the system from the pow-
■
er supply. Restart the system.
If the fault persists, replace the
lower fan.
Check connections on VCMU re-
■
frigerant circuit controller.
Check fan can rotate freely.
■
Check upper fan via actuator
■
test.
Isolate the system from the pow-
■
er supply. Restart the system.
If the fault persists, replace the
upper fan.