Defrosting; Main Controller Communication Failure; Indoor/Outdoor Communication Failure - Mitsubishi Electric EHSD-MEC.UK Service Manual

Error code Title and display conditions
P6 <Defrosting>
THW2 detects a temperature ≤15ºC and TH2
detects a temperature ≤−16ºC for consecutive 10
seconds.
E0/E4

Main controller communication failure

(Reception error)
Error code E0 is displayed if main controller does
not receive any signal from the indoor unit for ref.
address "0" for 3 minutes.
Error code E4 is displayed if indoor unit does
not receive any data from the main controller for
3 minutes or indoor unit does not receive any
signal from the main controller for 2 minutes.
E3/E5 Main controller communication failure
(Transmission error)
Error code E3 is displayed if the main controller
an not find an empty transmission path and thus
fails to transmit for 6 secs or the data received by
the main controller is different to what was sent
(by the main controller) 30 consecutive times.
Error code E5 is displayed if the FTC can not 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 consecutive
times.
E6

Indoor/outdoor communication failure

(Reception error)
Error 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.
E7 Indoor/outdoor communication failure
(Transmission error)
Error code E7 is displayed if signal "1" is received
30 consecutive times despite the FTC board
sending signal "0".
OCH571
Possible Cause
<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
controllers)
3. Fault on the indoor unit FTC board
section controlling Ref. address "0"
4. Fault with the main controller circuit
board
5. Electrical noise causes interference
with transmission/reception of data for
main controller.
1. 2 or more main controllers have been
connected to the FTC.
2. Fault with main controller transmission/
receiving circuit board
3. Fault with the main controller circuit
board
4. Electrical noise causes interference
with transmission/reception of data for
main 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.
1. Fault with FTC transmission/receiving
circuit board
2. Electrical noise causes interference
with power supply.
3. Electrical noise causes interference
with FTC-outdoor unit transmission ca-
ble.
46
Diagnosis and action
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
controller terminals.
2. Check main controller and FTC common
wiring max cable length 500 m.
Only use 2 core cable.
Only connect 1 main 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 controller circuit board should
be replaced.
1. Only connect 1 main 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 independ-
ently from the outdoor unit).
If the E3/E5 code is still displayed the FTC
and/or the main controller circuit board
should be replaced.
* 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
service 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 independ-
ently from the outdoor unit).
If the E6 code is still displayed the FTC
and/or the outdoor unit circuit board should
be replaced.
1. to 3.
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 independ-
ently from the outdoor unit).
If the E7 code is still displayed the FTC cir-
cuit board should be replaced.