Mitsubishi Electric EHSD-MED Service Manual page 48

Check code Title and display conditions
P6 Anti-freeze protection of plate heat exchanger
<Cooling>
The check code displayed when Ref. liquid temp.
(TH2) stays at −5ºC or lower for 10 seconds after
compressor operates for 6 minutes.
<Defrosting>
THW2 detects a temperature ≤15ºC and TH2
detects a temperature ≤−16ºC for consecutive 10
seconds.
E0/E4 Main remote controller communication failure
(Reception error)
Check code E0 is displayed if main remote con-
troller does not receive any signal from the indoor
unit for ref. address "0" for 3 minutes.
Check code E4 is displayed if indoor unit does
not receive any data from the main remote
controller for 3 minutes or indoor unit does not re-
ceive any signal from the main remote controller
for 2 minutes.
E3/E5 Main remote controller communication failure
(Transmission error)
Check code E3 is displayed if the main remote
controller cannot find an empty transmission
path and thus fails to transmit for 6 seconds or
the data received by the main remote controller
is different to what was sent (by the main remote
controller) 30 consecutive times.
Check code E5 is displayed if the FTC cannot
find an empty transmission path for 3 minutes
and thus cannot transmit or the data sent by the
FTC is different to what was expected 30 consec-
utive times.
E6 Indoor/outdoor communication failure
(Reception error)
Check code E6 is displayed if after the power is
switched ON to the indoor unit, the FTC board
does not receive any signal or the signal received
is not complete for 6 minutes, or after a period of
operation the FTC board does not receive any
signal or the signal received is not complete for 3
minutes.
OCH712C
Possible Cause
<Cooling>
1. Reduced water flow
• Clogged filter
• Leakage of water
2. Low temperature
• Low load
• Inlet water is too cold.
3. Defective water pump
4. Defective outdoor fan control
5. Overcharge of refrigerant
6. Defective refrigerant circuit (clogs)
7. Malfunction of linear expansion valve
<Defrosting>
1. Reduced water flow
• Clogged filter
• Leakage of water
2. Low temperature
• Low load
• Inlet water is cold.
3. Defective water pump
4. Leakage or shortage of refrigerant
5. Malfunction of linear expansion valve
1. Contact failure with transmission cable
2. Wiring procedure not observed.
(Cable length/cable diameter/number
of indoor units/number of main remote
controllers)
3. Fault on the indoor unit FTC board
section controlling Ref. address "0"
4. Fault with the main remote controller
circuit board
5. Electrical noise causes interference
with transmission/reception of data for
main remote controller.
1. 2 or more main remote controllers have
been connected to the FTC.
2. Fault with main remote controller
transmission/receiving circuit board
3. Fault with the main remote controller
circuit board
4. Electrical noise causes interference
with transmission/reception of data for
main remote controller.
1. Contact failure/short circuit/miswiring
2. Fault with outdoor unit transmission/
receiving circuit board
3. Fault with FTC transmission/receiving
circuit board
4. Electrical noise causes interference
with FTC-Outdoor unit transmission
cable.
48
Diagnosis and action
1., 2. Check water piping.
3. Check water pump.
4. Check outdoor fan motor.
5., 6. Check operating condition of refrigerant circuit.
7. Check linear expansion valve.
1., 2. Check water piping.
3. Check water pump.
4. Correct to proper amount of refrigerant.
5. Check linear expansion valve.
1. Check connection cable for damage or
loose connections at the FTC and main
remote controller terminals.
2. Check main remote controller and FTC
common wiring max cable length 500 m.
Only use 2-core cable.
Only connect 1 main remote controller to 1
FTC indoor unit board.
3. to 5.
If the problem is not solved by the above
measures then:
Turn the power to the indoor unit OFF and
then ON.
Power to both the indoor unit and outdoor
units should be switched OFF then ON. (This
may require switching 1 or 2 breakers de-
pending if the unit is powered independently
from the outdoor unit).
If the E4 code is still displayed the FTC and/
or the main remote controller circuit board
should be replaced.
1. Only connect 1 main remote controller to 1
FTC indoor unit board.
2. to 4.
Turn the power to the indoor unit OFF and
then ON.
Power to both the indoor unit and outdoor
units should be switched OFF then ON.
(This may require switching 1 or 2 breakers
depending if the unit is powered indepen-
dently from the outdoor unit).
If the E3/E5 code is still displayed the FTC
and/or the main remote controller circuit
board should be replaced.
Note:
Check the LED display on the outdoor unit
circuit board.
(Connect the A-control service tool, PAC-
SK52ST to test.) Refer to the outdoor unit ser-
vice manual for explanation of EA-EC codes.
1. Check the connections on the indoor and
outdoor units have not become loose and
that the connecting cable is not damaged.
2. to 4.
Turn the power to the indoor unit OFF and
then ON.
Power to both the indoor unit and outdoor
units should be switched OFF then ON.
(This may require switching 1 or 2 breakers
depending if the unit is powered indepen-
dently from the outdoor unit).
If the E6 code is still displayed the FTC
and/or the outdoor unit circuit board should
be replaced.