Fault indication by flashing code
Sensor resistance
Opera-
tion
LED
Timer
LED
Defrost
fan
LED
Alarm
LED
OC
display
Cause
Required action
Flashes
rapidly
Flashes
rapidly
E0
EEPROM error
Check that EEPROM is firmly
in place
*Flashes
slowly
E2
Communication error between OC &
IU PCBs
Check electrical connection
leads
For RXT 1051 DC and up
E3
Communication error between OC
main board & OC inverter board
Check wiring
** Flashes
slowly
E4
Outdoor temp. sensor on OC tripped
Check resistance and
temperature on sensor
E5
Compressor overvoltage
Check compressor voltage
P0
Compressor excess temperature
Allow compressor to cool
P1
High pressure switch has triggered
Check refrigerant pressure
P2
Low pressure switch has triggered
Check refrigerant pressure
P3
Compressor power consumption too high
Check compressor power
consumption
P4
Hot gas temperature over 105°C
Clean condenser, check
refrigerant circuit
P5
Condenser temperature over 65°C
Clean condenser, check
refrigerant circuit
P6
Voltage protection, OC main board
Check voltage
Flashes
rapidly
* Flashes
rapidly
Air circulation / condenser sensor
tripped
Check resistance
Flashes
rapidly
Communication error between OC & IU
Check electrical connection
leads
Flashes
rapidly
Operating mode fault
Switch system off
Flashes
slowly
Flashes
slowly
Flashes
slowly
Flashes
slowly
Condenser / outdoor temp. sensor
faulty or not correctly connected
Read off fault code on OC
Check sensors
IT vaporiser sensor, IT circulation sensor
Temperature °C
Resistance
0
35.20 k
Ω
5
26.88 k
Ω
10
20.72 k
Ω
15
16.12 k
Ω
20
12.64 k
Ω
25
10.00 k
Ω
30
7.97 k
Ω
35
6.40 k
Ω
* RXT 521 DC ** RXT 681 DC
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