REMKO SuperTec-Monitor - Manual (Page 27)

Fault code Meaning Cause Remedial measures
U4
Open circuit/short-circuit on
the temperature sensors of
the outdoor unit (TH3, TH32,
TH33, TH6, TH7 and TH8).
If no resistance (0 Ω) or infinite
resistance (∞ Ω) is measured
by one of the temperature
sensors when the condenser
is operational, fault message
"U4" is issued.
With the help of the system
monitor on the outdoor
unit, you can detect which
temperature sensor is affected
(this function is not available
in the first 10 mins after the
condenser begins operation,
after the conclusion of defrost
mode or while defrost mode is
operational.)
Poor or detached contacts of
the cables and connectors of
one or more of the temperature
sensors on the control board.
Temperature sensor defective.
Control board of the outdoor
unit defective.
Check connectors and contacts
of the temperature sensors on
the control board and repair.
Check connection cables of the
temperature sensors for cable
break or similar.
Check the temperature sensor
with the help of the system
monitor and proceed accordingly
in order to rectify the fault.
Replace defective control board
of the outdoor unit
Name Description Open(XX),at Short-circuit (0X), at
TH3, TH32, TH33 Cable temperature sensor -40°C and lower 90°C and higher
TH6 Two-phase mixture -40°C and lower 90°C and higher
TH7 Outdoor air -40°C and lower 90°C and higher
TH8 Inverter cooling block -27°C and lower 102°C and higher
U5
Temperature fault on inverter
cooling block
If the temperature at TH8
on the inverter cooling block
reaches or exceeds the value
specified below, fault message
"U5" is issued.
CMF80/90: 77°C
CMT100: 77°C
CMF140/150: 95°C
CMT150: 95°C
Fan motor jammed.
Fault on the fan motor.
Air inlets and outlets dirty/
blocked.
Increase in outside air
temperature.
Temperature sensor defective.
Input circuits (supply voltage)
on the voltage board of the
outdoor unit defective.
Drive circuit of the outdoor unit
fan defective.
Check fan motor. Check air inlets
and outlets and clean.
Check whether other weather-
related causes are responsible for
the rise in temperature.
Upper temperature limit 46°C.
Switch the supply voltage off
and back on. Check if fault "U5"
is issued again within the next
half hour.
If "U4" is issued, rather
than "U5", you can find the
descriptions under "U4".
Measure the resistance of the
temperature sensor TH8 or use
the system monitor to query the
temperature at TH8. Replace
defective temperature sensor.
Replace defective voltage board
on the outdoor unit.
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