Technical data

Table Of Contents
FAULTS
6 720 803 687 (2012/11)66
U7 Overheating faulty due to
insufficient hot gas temperature
Fault display “U7” is shown when
superheating of -15 °C lasted longer
than 3 minutes, with the LEV almost
closed (lowest pulse rate) and
10 minutes have passed since the
compressor started.
Poor connection/contacts or terminal loose at the
cables and plugs of hot gas temperature sensor
TH4 on the PCB.
Check and repair contacts, cables and connections for
temperature sensor TH4.
Faulty fixing of hot gas temperature sensor TH4. Secure temperature sensor TH4 correctly.
Poor connection/contacts or terminal loose at the
cables and plugs on the LEV drive.
Check connections, contacts and terminals on the LEV
drive and repair or replace if required.
Poor or loose contacts at the LEV cables on the
PCB.
Check and repair contacts, cables and connections of the
LEV cables.
Faulty linear expansion valve (LEV). Check linear expansion valve (LEV) and replace if required.
U8 Fan motor speed fault
The speed on the fan motor is
determined to be faulty if
a maximum of only 100 rpm is
measured for a period of 15
seconds at an outside
temperature of 20 °C or above
less than 50 rpm or more than
1500 rpm is measured for a
period of one minute
Fan motor faulty. ▶Check fan motor and replace faulty motor.
Circuit board faulty. Check PCB and replace, if faulty.
U9 Inverter over or undercurrent and
fault in the serial PCB
communication
Sudden drop in bus voltage
below 200 V
Increase in bus voltage above
420 V
External unit power consumption
drops to only 0.1 A at an
operating frequency of 40 Hz or a
compressor current of 6.0 A.
Increase in supply voltage (mains side). Check supply voltage on mains side.
Wiring detached from compressor. Check and correct wiring on compressor and power circuit
board.
Faulty PFC module on external unit power circuit
board.
▶Replace PCB.
Faulty ACT module. ▶Replace ACT module.
CNAF plug detached or disconnected. Check and correct fit and wiring of CNAF.
Faulty 52C circuit on PCB. ▶Replace PCB.
CN5 plug on power circuit board detached or
disconnected.
Check and correct fit and wiring of CN5.
CN2 plug on power circuit board detached or
disconnected.
Check and correct fit and wiring of CN2.
Code Description Cause Possible solution / check
Table 39 Fault indications, external unit