Aa Cancel Defrost - Viessmann VITOTRONIC 200 Service Instructions Manual

Message overview
(cont.)

AA Cancel defrost

: Compressor remains off until the flow tempera-
ture in the secondary circuit has reached 15 °C.
Booster heaters are started if necessary (instan-
taneous heating water heater or external heat
generator).
: Switch to central heating/DHW heating
Cause
Flow or return temperature in the secondary circuit
■
too low during defrosting
The pipework flow rate may be too low
■
AB Instant.htg wtr heater
Instantaneous heating water heater does not start up.
Cause
Instantaneous heating water heater faulty
■
High limit safety cut-out has responded.
■
No temperature rise within 24 h
■
AC compressor block
■ The compressor shuts down permanently in order to
prevent appliance damage.
Central heating and DHW heating is only possible
■
with booster heaters.
Cause
Temperature sensors in the refrigerant circuit are faul-
■
ty
Pressure sensor faulty
■
Safety high pressure switch has responded.
■
Electronic expansion valve faulty
■
Compressor drive faulty
■
: Fan faulty
■
Measure
Provide additional heating water buffer cylinder in the
secondary circuit return.
!
Please note
If the temperature in the secondary circuit is too
low, the condenser may freeze up or a thick lay-
er of ice may form on the evaporator.
Only acknowledge the fault message when the
flow temperature in the secondary circuit has
reached at least 15 °C.
Measure
Danger
Contact with live components can lead to seri-
ous injury from electric current.
Isolate the power supply prior to starting work
on the appliance.
Check power supply, connecting cable and plug for
■
the instantaneous heating water heater.
Check instantaneous heating water heater control
■
signal at terminals 211.3 (stage 1, see "Main PCB")
and 224.4 (stage 2, see "Expansion PCB").
Check high limit safety cut-out, and reset if required.
■
Check instantaneous heating water heater.
■
Measure
Calling up further heat pump messages: "Message
■
history"
Observe messages from the refrigerant circuit con-
■
troller: "Diagnosis" "Refrigerant circuit"
sage history"
Check temperature sensors in the refrigerant circuit.
■
Check pressure sensor.
■
Check safety high pressure switch.
■
Check electronic expansion valve.
■
Check compressor drive.
■
Troubleshooting
"Mes-
93