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SPECIFIC FAULT DIAGNOSIS FOR CC875 ‘E’ UNITS
A fully electronic system comprising CC875 ‘E’ with MHPUE or DCUE communicates between the units by digital codes. Signals are
transmitted every 10 seconds, therefore a delay of up to 10 seconds could occur before the system responds to a command. Similarly if
the communication link is broken, the outdoor unit will shut down within 15 seconds. To reset: Switch the mains off to both indoor and
outdoor units to reset the microprocessor; the current programme is retained in the indoor pcb memory.
Check for alarms i.e.
i Audible alarm or LEDs flashing - see below
ii
If NO external connections are made to alarm terminal 5, the presence of an alarm condition can be checked for by testing continuity
between L and 5; Alarm = 220ohms, Clear = open circuit. WARNING: All parts of the circuit are at high voltage, if any external
connections are made to terminal 5, the continuity meter will be damaged
The outdoor unit can be forced to operate for test purposes by temporarily linking live directly to terminal 3
(up to 20 seconds delay)
L
Outdoor unit runs continually at
high speed
Charge link JP6 still fitted Remove JP6 charge link
MHPUE in heating Normal
Minimum speed adjustment set too high Reset minimum speed
If all external devices appear O.K. the pcb may need to be replaced
M No LED's lit or flashing No mains supply or internal fuse blown Check electrical supply and fuses
Fan motor plug disconnected Reconnect fan motor plug
Motor internal thermal protector operated Check motor and rectify
Ribbon cable to fascia not connected Reconnect
Receiver pcb fault Check circuit board and replace
N
Regular audible pulsed signal -
all LED's lit
Indoor temperature sensor problem
Disconnect data link to identify which unit, if
fault clears it is outdoor unit
Outdoor sensor problem Replace outdoor unit sensor
O
Indoor unit continues after
stop/off command
Overrun of 30 seconds in heating NORMAL
P
Unit will not respond to infrared
commands.
No audible answer signal
Handset not plugged into wall bracket (if
appropriate). Fault in connections between wall
bracket and indoor unit
Plug in correctly and check connections
Battery discharged Replace battery
Operating in charge mode Remove charge link from outdoor unit
Q
Unit answers infrared
commands
with double audible signal
Communications not yet established. Wait 2
minutes from power up
If electric heater is known to be fitted, double
signal indicates open circuit element or thermal
protector
Demanded mode not available
Double signal in response to on/off command
indicates under time control
R
Sounder beeps and LED(s) flash
0.5s ON, 0.5s OFF
Warning of alarm status Details below
S
All LED's lit and continuous
audible signal
Microprocessor fault Replace indoor unit pcb assembly
T Short cycles between cool and
heat
System oversized for room Use cool or heat programmes NOT 'Auto' and
set to lower speed
HANDSET: If the handset fails to respond to button operations, disconnect and then reconnect the battery.
The previous programme state is retained in the memory.
LED STATUS AND ALARM INDICATIONS
Status display LED Flash Rate ON/OFF
(seconds)
Sounder Condition Status
Red Amber Green
C ON OFF In Operation Normal
F ON OFF Heating Demand Normal
D ON OFF Cooling Demand Normal
C 0.5 / 5.0 OFF Standby Normal
C 0.5 / 15 OFF Clock Controlled Standby Normal
C 2 x 0.5 / 15 OFF Setback Normal
C 0.5 / 0.5 OFF Filter Clean Advisable Normal
Alarm indications F 0.5 / 0.5 BEEPS Network Warning Call Engineer
D 0.5 / 0.5 BEEPS High Condensate Level Call Engineer
C F 0.5 / 0.5 BEEPS Low Pressure Warning Call Engineer
C D 0.5 / 0.5 BEEPS High Pressure Warning Call Engineer
C F D 0.5 / 0.5 BEEPS Contactor Overload Operated Call Engineer
F D 0.5 / 0.5 BEEPS Outdoor Fan Fail Call Engineer
C F D ON BEEPS Sensor Fault Call Engineer
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