Appendix
46
Installation and maintenance instructions flexoTHERM exclusive 0020213395_00
Code
Meaning
Cause
Remedy
F.735
Evaporation temperature too high
–
Temperature in the environment cir-
cuit (heating mode) or building cir-
cuit (cooling mode) too high for com-
pressor operation
–
Feeding of external heat into the
environment circuit
–
Reduce or stop the external heat
that is entering
–
Check the de-icer (does it heat
up even though it is
Off
in the
sensor/actuator test?)
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the compressor inlet sensor
and low-pressure sensor
F.737
Condensation temperature too
high
–
Temperature in the building circuit
(heating mode) or environment cir-
cuit (cooling mode) too high for com-
pressor operation
–
Coolant volume too high
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the compressor inlet sensor,
high-pressure sensor and low-pres-
sure sensor
–
Check the refrigerant volume (see
Technical data)
F.740
Environment cir. inlet temperature
too low
–
Inlet temperature in the environment
circuit too low for the compressor to
start for heating:
–
Air/brine: Environment circuit inlet
temperature < -28 °C
–
Ground/brine: Environment circuit
inlet temperature < -7 °C
–
Groundwater/brine: Groundwater
inlet temperature < 2 °C
–
Check the dimensioning of the envir-
onment circuit
–
Check the sensors
F.741
Building circuit inlet Return tem-
perature too low
–
Return temperature in the building
circuit too low for the compressor to
start
Heating:
–
Return temperature < 5 °C
Cooling:
–
Return temperature < 10 °C
–
Heating: Check that the four-way
valve functions correctly
F.742
Environment cir. inlet temperature
too high
–
Inlet temperature in the environment
circuit too high for the compressor to
start
–
Brine inlet temperature > 50 °C
–
Feeding of external heat into the
environment circuit
–
Heating: Check that the four-way
valve functions correctly
–
Check the environment circuit
–
Check the sensors
–
Reduce or stop the external heat
that is entering
F.743
Building circuit inlet Return tem-
perature too high
–
Return temperature in the building
circuit too high for the compressor to
start
Heating:
–
Return temperature > 55 °C to 60 °C
(depending on the brine inlet temper-
ature)
Cooling:
–
Return temperature > 35 °C
–
Cooling: Check that the four-way
valve functions correctly
–
Check the sensors
F.783
Connection error: Terminal block
(TMB)
Cable not connected or connected incor-
rectly
Check the connection line between the
mains connection PCB and the controller
PCB
F.784
Connection error: ICL
Cable not connected or connected incor-
rectly
Check the connection line between the
mains connection PCB and the in-rush
current limiter PCB
