Technical data

Table Of Contents
FAULTS
6 720 803 687 (2012/11) 67
Ud Overheating protection (overload
protection, fan motor fault)
If the line temperature (TH3)
exceeds 70 °C, fault display “Ud” is
shown.
Temperature sensor TH3 faulty. Check temperature sensor, replace faulty temperature
sensor.
Circuit board faulty. ▶Check PCB, replace if faulty.
UF Protective equipment against
compressor overcurrent:
compressor blocked
If overcurrent is measured in the DC-
BUS or in the compressor 30
seconds after the compressor start,
fault display “UF” is shown.
Shut-off valves closed. ▶Open shut-off valves.
Reduced supply voltage (mains side). Check supply voltage on mains side.
Plug detached or disconnected, cable break,
phases reversed.
Check and correct wiring on compressor and power circuit
board and replace faulty components.
Compressor faulty. Replace external unit.
Power circuit board faulty. Replace power circuit board.
DIP switches set incorrectly. Check settings on the external unit PCB.
UH Current sensor fault
Fault display “UH” is shown if the
voltage sensor captures a voltage
between -1.5 V and +1.5 V. This
fault is ignored in test mode.
Poor connection/contacts or terminal loose on
compressor supply cables.
Check and correct compressor wiring.
Faulty circuit (current sensor) on the external unit
power circuit board.
Replace faulty external unit power circuit board.
Code Description Cause Possible solution / check
Table 39 Fault indications, external unit