Appendix
54
Installation and maintenance instructions Hydraulic Station 0020291544_01
Code
Meaning
Cause
Remedy
F.731
High-pressure switch open
–
Refrigerant pressure too high. The
integrated high-pressure switch
in the outdoor unit has tripped at
41.5 bar (g) or 42.5 bar (abs)
–
Insufficient energy output via the
condenser
–
Purging the building circuit
–
Too low a volume flow as a result
of closing single room controls in an
underfloor heating system
–
Check that the dirt filter that is in
place is permeable
–
Refrigerant flow rate too low (e.g.
electronic expansion valve defective,
4-port diverter valve is mechanically
blocked, filter is blocked). Inform
customer service.
–
Cooling mode: Check the fan unit for
dirt
–
Check the high-pressure switch and
high-pressure sensor
–
Reset the high-pressure switch and
carry out a manual reset on the
product.
F.732
Compressor outlet temperature
too high
The compressor outlet temperature is
above 110 °C:
–
Application limits exceeded
–
EEV does not work or does not open
correctly
–
Refrigerant volume too low (frequent
defrosting due to extremely low
evaporation temperatures)
–
Check the compressor inlet sensor
and outlet sensor
–
Check the compressor outlet temper-
ature sensor (TT135)
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the refrigerant volume (see
Technical data)
–
Carry out a leak-tightness test
–
Check whether the service valves on
the outdoor unit are open.
F.733
Evaporation temperature too low
–
Insufficient air volume flow through
the outdoor unit's heat exchanger
(heating mode) leads to an insuffi-
cient energy input in the environment
circuit (heating mode) or building cir-
cuit (cooling mode)
–
Refrigerant volume too low
–
If the building circuit contains ther-
mostatic valves, check that they are
suitable for cooling mode (check
volume flow in cooling mode)
–
Check the fan unit for dirt
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the compressor inlet sensor
–
Check the refrigerant volume
F.734
Condensation temperature too low
–
The temperature in the heating
circuit is too low, outside of the
operating characteristics
–
Refrigerant volume too low
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the compressor inlet sensor
–
Check the refrigerant filling volume
(see technical data)
–
Check whether the 4-port diverter
valve is in an intermediate position
and is not correctly switched
–
Checking the high-pressure sensor
–
Check the pressure sensor in the
heating circuit
F.735
Evaporation temperature too high
–
Temperature in the environment
circuit (heating mode) or building
circuit (cooling mode) too high for
compressor operation
–
Feed-in of external heat into the
environment circuit due to increased
fan speed
–
Check the system temperatures
–
Check the refrigerant filling volume
for overfilling
–
Check the EEV (does the EEV
move to the limit stop? Use
sensor/actuator test)
–
Check the sensor for the evaporation
temperature (depending on the
position of the 4-port diverter valve)
–
Check the volume flow in cooling
mode
–
Check the air volume flow in heating
mode
