Technical data

Table Of Contents
FAULTS
6 720 803 687 (2012/11) 69
E9 Communication error between
internal and external unit —
transmission error
Fault display “E9” is shown in the
following cases (on the external unit
only).
Failed 30 times to receive a “0”
when a “1” is expected.
•The external unit cannot transmit
a signal within 3 minutes because
the lines are busy.
Poor connection/contacts or terminal loose on the
control cables, cable break.
Check and correct wiring for all control cables between
internal and external unit.
Faulty transmitter/receiver circuit on external unit. Switch the supply voltage off and on again (reset system).
Check if fault display “E9” is shown again after the restart.
Check PCBs of the internal and external units and replace if
faulty.
Noise in the voltage system.
Noise in the control cables.
EF Unknown fault
An unknown fault was received and
fault display “EF” is shown.
Noise in the control cables between internal and
external unit.
Switch the supply voltage off and on again (reset system).
Check if fault display “EF” is shown again after the restart.
Check PCBs of the internal and external units and replace if
faulty.
The external unit is not a power inverter model. Use a power inverter external unit.
Ed Communication error — serial
operating signal
There has been a fault in the
communication between the power
circuit board and the PCB in the
external unit.
Poor connection/contacts or terminal loose at the
terminal of the connection cables between the
PCB and the power circuit board of the external
unit (CN2). Cable break.
Check wiring and plug CN2 and CN4 between the PCBs and
correct if required.
Poor connection/contacts or terminal loose at the
terminal of the connection cables between the
PCB and the power circuit board of the external
unit (CN4). Cable break.
Faulty power circuit board communication circuit. Check power circuit board.
Faulty PCB communication circuit. ▶Check PCB.
P8 Pipe work temperature TH
Ten seconds after the compressor
start, the “Hot Adjust” heat-up mode
is already completed, fault display
“P8” is shown if the heating
temperature is out of range for at
least 20 minutes.
To identify these faults takes 27
minutes. This check is not
implemented in defrost mode. The
check restarts after the defrost
mode has terminated. Permissible
temperature range in heating mode:
3K pipe work temperature of the
internal unit (TH5) — 18 °C (TH1).
Slow increase of temperature differential between
room temperature and pipe work temperature
(line or heat exchanger) in the internal unit due to:
Refrigerant shortage
Temperature sensor in the internal unit
detached from its holder.
Refrigerant circuit fault.
Check internal unit temperature sensor using the system
monitor (external unit PCB or “PAC-SK52ST” diagnostic
device).
TH1 = 7 K (equals 18 °C)
Capturing error at temperature sensor TH5.
Refrigerant lines reversed. Check pipe work and wiring.
Control lines reversed.
4-way valve faulty. Check functioning of 4-way valve.
Code Description Cause Possible solution / check
Table 39 Fault indications, external unit