Mitsubishi Electric EHPT20Q-VM2EA Service Manual page 43

No. Fault symptom
5 LED2 on FTC is When LED1 is also blinking on FTC .
blinking.
Faulty wiring between FTC and outdoor unit
(See 6. WIRING
When LED1 on FTC is lit.
DIAGRAM)
1. Faulty wiring in main remote controller
Multiple indoor units have been wired to a
single outdoor unit.
2. Short-circuited wiring in main remote control-
ler
3. Main remote controller failure
6 LED4 on FTC is off. 1. SD memory card is NOT inserted into the
(See 6. WIRING memory card slot with correct orientation.
DIAGRAM)
2. Not an SD standards compliant memory card.
LED4 on FTC is 1. Full of data.
blinking.
2. Write-protected.
(See 6. WIRING
3. NOT formatted.
DIAGRAM)
4. Formatted in NTFS file system.
7 No water at hot tap. 1. Cold main off
2. Strainer (local supply) blocked.
8 Cold water at tap. 1. Hot water run out.
2. Prohibit, schedule timer or holiday mode se-
lected.
3. 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. 3-way valve fault
8. Air inclusion in pump A
9. System or power OFF
10. Flow sensor fault
11. Supply flow rate is low
9 Water heating takes 1. Heat pump not working.
longer.
2. Booster heater cut-out tripped.
3. Booster heater breaker (ECB1) tripped.
4. The booster heater thermal cut-out has
tripped and cannot be reset using the manual
reset button.
5. Flow rate of the primary circuit may be reduced.
6. 3-way valve failure
GCH15010
Possible cause Explanation - Solution
Check for faulty wiring between FTC and outdoor unit.
1. Check for faulty wiring in main remote 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.
2.,3. Remove main remote controller wires and check LED2 on FTC. (See 6. WIR-
ING DIAGRAM.)
If LED2 is blinking check for short circuits in the main remote controller wiring.
- if LED2 is blinking, the main remote controller is faulty;
- if LED2 is lit, faulty wiring of the main remote controller has been corrected.
1. Correctly insert SD memory card in place until a click is heard.
2. Use an SD standards compliant memory card. (Refer to installation manual,
"5.6 Using SD memory card".)
1. Move or delete data, or replace SD memory card with a new one.
2. Release the write-protect switch.
3. Refer to installation manual, "5.6 Using SD memory card".
4. FTC is Not compatible with NTFS file system. Use an SD memory card
formattedin FAT file system.
1. Check and open stop cock.
2. Isolate water supply and clean strainer.
1. Ensure DHW mode is operating and wait for thermal store tank to re-heat.
2. Check settings and change as appropriate.
3. 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 black 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.
Check plumbing/wiring to 3-way valve.
7.
(i) Manually override 3-way valve using the main remote controller. (Refer to
<Manual operation> in section 9-4.) If the valve does not still function, go
to (ii) below.
(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.)
8. Open the air vent above pump A (refer to page 25).
9. Turn on the power / system.
10.
flow sensor A.
11. Increase the supply amount.
1. Check heat pump – consult outdoor unit service manual.
2. Check booster heater thermostat and press reset button if safe.
Reset button is located on the side of booster heater, covered with black rub-
ber cap. See 4. PART NAMES AND FUNCTIONS to find out its position.
3. Check the cause and reset if safe.
4. Check resistance across the thermal cut-out, if open then connection is bro-
ken and the booster heater will have to be replaced.
Contact your Mitsubishi Electric dealer.
5. Check the following items
Check for trapped air in water pump 1 (primary circuit).
Check water pump (primary circuit) for malfunction. (Refer to section 10-6.)
Check the pipe for blockage.
6. Check plumbing/wiring to 3-way valve.
(i) Manually override 3-way valve using the main remote controller. (Refer to
<Manual operation> in section 9-4.) If the valve does not still function, go to (ii)
below.
(ii) Replace 3-way valve motor. If the valve does not still function, go to (iii) be-
low.
(iii) Replace 3-way valve. (Refer to 11. DISASSEMBLY PROCEDURE.)
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