54
Installation and maintenance instructions 0020213394_05
Code
Meaning
Cause
Remedy
F.741
Building circuit: Return temp.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 4-port valve
functions correctly
F.742
Environment circuit: Inlet temp.
too high
–
Inlet temperature in the environment
circuit too high for the compressor to
start
–
Brine inlet temperature > 50 °C
–
Feed-in of external heat into the
environment circuit
–
Heating: Check that the 4-port valve
functions correctly
–
Check the environment circuit
–
Check the sensors
–
Reduce or stop the external heat
that is entering
F.743
Building circuit: Return temp. 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 4-port valve
functions correctly
–
Check the sensors
F.782
Connection error: Fan unit 2:
–
No electrical connection
No eBUS connection
–
Check the electrical connection to
fan unit 2 (check the line connection;
contact fault? Has the circuit breaker
tripped in the connection box?)
–
Check the eBUS connection to fan
unit 2
–
Check the address switch position
on the PCB of fan unit 2. Required
switch position: 2
F.783
Connection error: Terminal block
(TMB)
Cable not connected or connected incor-
rectly
Check the connection cable between the
power supply PCB and the control PCB
F.784
Connection error: ICL
Cable not connected or connected incor-
rectly
Check the connection cable between
the power supply PCB and the in-rush
current limiter
F.785
Fan unit 2: Fan blocked
–
There is no confirmation signal stat-
ing that the fan is rotating
–
Check the air route and, if required,
remove any blockages
–
Check and, if required, replace the
F1 fuse on the PCB in the fan unit
(OMU)
F.786
Fan unit 2: Safety cut-out open
–
The safety cut-out on the de-icer is
open due to insufficient volume flow
and/or brine temperatures above
65 °C
–
Operating the de-icer outside of the
permitted area of application
–
De-icer operation when the brine
circuit is not filled
–
During de-icer operation at brine
temperatures above 115 °C, the
safety fuse of the safety cut-out
is tripped and the fuse must be
replaced.
–
Checking for circulation in the envir-
onment circuit pump
–
If required, open the stopcocks. The
safety cut-out is automatically reset
as soon as the temperature at the
fuse falls below 30 °C again. If the
safety cut-out is still open at a de-
icer temperature below 65 °C (or
30 °C), temperatures above 115 °C
were reached and the safety fuse
tripped.
–
Check and, if required, replace the
F1 fuse of the air-to-brine collector
–
Replace the safety cut-out