Mitsubishi Electric EHST20C-VM6HB Service Manual page 61

No. Fault symptom
LED2 on FTC4 is off. <FTC4 powered on independent source>
4.
1. FTC4 is not supplied with 220 to 240V AC.
(See 6. WIRING
DIAGRAM)
. There are problems in the method of
connecting the connectors.
. FTC4 failure.
When LED1 on FTC4 is lit.
Incorrect setting of refrigerant address for
outdoor unit.
(None of the refrigerant address is set to "0".)
LED2 on FTC4 is When LED1 is also blinking on FTC4 .
5
blinking.
Faulty wiring between FTC4 and outdoor
(See 6. WIRING
unit
DIAGRAM) When LED1 on FTC4 is lit.
1. Faulty wiring in main controller
Multiple indoor units have been wired to a
single outdoor unit.
. Short-circuited wiring in main controller
. Main controller failure
LED4 on FTC4 is off.
6 1. SD memory card is NOT inserted into the
memory card slot with correct orientation.
(See 6. WIRING
DIAGRAM)
. Not an SD standards compliant memory card.
LED4 on FTC4 is 1. Full of data.
blinking.
. Write-protected.
(See 6. WIRING
. NOT formatted.
DIAGRAM) 4. Formatted in NTFS file system.
No water at hot tap.
7 1. Cold main off
. Strainer (field supply) blocked.
Cold water at tap. 1. Hot water run out.
8
. Prohibit, schedule timer or holiday mode se-
lected.
. Heat pump not working.
4. Booster heater cut-out tripped.
5. The earth leakage circuit breaker for booster
heater breaker (ECB1) tripped.
6. The booster heater thermal cut-out has
tripped and cannot be reset using the manual
reset button.
7. Immersion heater cut-out tripped.
8. Immersion heater breaker (ECB) tripped.
9. 3-way valve fault
OCH531
Possible cause
61
Explanation - Solution
1. Check the voltage across the L and N terminals on the indoor power supply
terminal block. (See 7. FIELD WIRING.)
• When the voltage is not 220 to 240V AC, check for faulty wiring to power
supply.
• When the voltage is 220 to 240V AC, go to 2. below.
Check for faulty wiring between the connectors.
.
• When the connectors are wired incorrectly re-wire them correctly referring
to below. (See 7. FIELD WIRING and a wiring diagram on the control and
electrical box cover.)
L
N
Black
CN01
FTC4 powered
from independent S1
Cylinder unit
source
control board
S2
S3
• If no problem found with the wiring, go to 3. below.
. Check the FTC4 control board.
• Check the fuse on FTC4 control board.
• Check for faulty wiring.
• If no problem found with the wiring, the FTC4 control board is faulty.
Recheck the refrigerant address setting on the outdoor unit.
Set the refrigerant address to "0".
(Set refrigerant address using SW1(3 - 6) on outdoor controller circuit board.)
Check for faulty wiring between FTC4 and outdoor unit.
1. Check for faulty wiring in main controller.
The number of indoor units that can be wired to a single outdoor unit is one.
Additional indoor units must be wired individually to a single outdoor unit.
.,. Remove main controller wires and check LED2 on FTC4. (See 6. WIRING
DIAGRAM.)
• If LED2 is blinking check for short circuits in the main controller wiring .
• If LED2 is lit, wire the main controller again and:
- if LED2 is blinking, the main controller is faulty;
- if LED2 is lit, faulty wiring of the main controller has been corrected.
1. Correctly insert SD memory card in place until a click is heard.
. Use an SD standards compliant memory card. (Refer to installation manual,
"5.5 Using SD memory card".)
1. Move or delete data, or replace SD memory card with a new one.
. Release the write-protect switch.
. Refer to installation manual, "5.5 Using SD memory card".
4. FTC4 is Not compatible with NTFS file system. Use an SD memory card for-
matted in FAT file system.
1. Check and open stop cock.
. Isolate water supply and clean strainer.
1. Ensure DHW mode is operating and wait for DHW tank to re-heat.
. Check settings and change as appropriate.
. Check heat pump – consult outdoor unit service manual.
4. Check booster heater thermostat and press reset button if safe.
Reset button is located on the side of booster heater, covered with white rub-
ber cap. See 4. PART NAMES AND FUNCTIONS to find out its position.
5. Check the cause and reset if safe.
6. Check resistance across the thermal cut-out, if open then the connection is
broken and the booster heater will have to be replaced.
Contact your Mitsubishi Electric dealer.
7. Check immersion heater thermostat and press reset button, located on im-
mersion heater boss, if safe. If the heater has been operated with no water
inside it may have failed, so please replace it with a new one.
8. Check the cause and reset if safe.
9. Check plumbing/wiring to 3-way valve.
(i) Manually override 3-way valve using the main controller. (Refer to <Manual
operation> in section 9-2.) If the valve does not still function, go to (ii) be-
low.
(ii) Replace 3-way valve coil. If the valve does not still function, go to (iii) be-
low.
(iii) Replace 3-way valve. (Refer to 11. DISASSEMBLY PROCEDURE.)