22/25
55208033-08
SPECIFIC FAULT DIAGNOSIS FOR L UNITS
CONDITION
POSSIBLE CAUSE
ACTION
Check for alarms
i
LEDs flashing - see table below
ii
If NO external connections are made to alarm terminal 5, the presence of an alarm condition can be tested for by checking for mains voltage at
terminal 5; full mains voltage = Alarm; less than mains voltage = Clear.
The outdoor unit can be caused 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
Charge link still fitted
Remove charge link
speed
MHPUL in heating
Normal
Minimum speed adjustment set too high
Reset minimum speed
If all external devices test O.K. the outdoor unit pcb must be replaced
M
No LED's lit or flashing
Unit commanded to be OFF
Transmit 'ON'
No mains supply or internal fuse blown. (Fuse F2
on internal control board blown during configuring)
Check electrical supply and fuses
Fan motor plug disconnected
Reconnect fan motor plug
Motor internal thermal protector operated
Check motor and rectify
Cables to fascia not connected
Reconnect
Circuit board fault
Check circuit board and replace
High water level
Check pump circuit (if fitted)
N
All LED's lit, one flashing
Temperature sensor problem
See table below
Resistor problem (non MHPUL)
Check resistor connected
Outdoor sensor problem (MHPUL)
Replace outdoor unit sensor/check
interconnecting wiring
P
Indoor unit continues after stop/off
Overrun of 30 seconds in heating
Normal
Q
Unit will not respond to infrared commands. Battery discharged
Replace battery
Handset
corrupted
Reset
R
Unit does not switch on/off at
intended times
Power cut has occurred
Send any command from the handset to
synchronise the timer
S
Unit not running in intended
mode/temperature
Power has been shut off for three or more days,
unit is exercising default programme
Use handset retransmit button
T
Fan does not run at the intended
speed
Heat Pumps Only
Fan runs at low speed until indoor coil is warm,
then changes to intended speed
U
Short cycles between cool and heat
System oversized for room
Use cool or heat programmes NOT 'Auto'
V
First operation, room is overcooled
or overheated by 2°C
Set point temperature reverts to normal after
deadband is reached or 20 minutes of
operation
Normal
W
Handset will not transmit
Heating commands
Incorrectly configured - see page 23
Any commands
Battery flat
X
Compressor runs on
Automatic minimum run time of 1.5 minutes
Normal
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 for a few seconds provided none of the user buttons are pressed.
LED STATUS AND ALARM INDICATIONS
Cool
Dry
Fan
Heat
DIAGNOSTICS
D
I
4
F
Green
Red
Red
Amber
OFF
OFF
OFF
OFF
No power, manual OFF, timed OFF, condensate
high level, fault in condensate control
ON
OFF
ON
OFF
Cooling mode selected
ON
OFF
ON
BLINKS
AUTO - predominantly cooling
OFF
OFF
ON
ON
Heating mode selected
BLINKS
OFF
ON
ON
AUTO - predominantly heating
OFF
OFF
ON
OFF
Fan mode selected
OFF
ON
ON
OFF
Dry mode selected
OFF
OFF
OFF
BLINKS
Outdoor unit defrosting
Diagnostics
OFF
OFF
BLINKS x 4
OFF
Room sensor missing
OFF
OFF
BLINKS x 4
OFF
Indoor coil sensor missing
OFF
BLINKS
BLINKS x 4
OFF
Heat pump only, outdoor coil sensor missing
BLINKS
OFF
BLINKS x 1
OFF
Compressor overload
Heronhill - for all your Marstair requirements
Tel: 01823 665660
www.heronhill.co.uk
Fax: 018123 665807
