Mitsubishi Ecodan fault 4

What it means

LED2 on the FTC control board is off when the FTC is powered from an independent source rather than via the outdoor unit, indicating power supply or connector wiring issues.

Likely causes

1. Outdoor unit not supplied at rated voltage
2. Defective outdoor controller circuit board
3. FTC not supplied with 220 to 240V AC (independent source)
4. FTC failure
5. Faulty connector wiring
6. Problems in the method of connecting the connectors (independent source)
7. Incorrect setting of refrigerant address for outdoor unit (none set to '0') when LED1 is lit
8. Contact failure with transmission cable
9. Wiring procedure not observed (cable length/cable diameter/number of indoor units/number of main remote controllers)
10. Fault on the indoor unit FTC board section controlling Ref. address "0"
11. Fault with the main remote controller circuit board
12. Electrical noise causes interference with transmission/reception of data for main remote controller

Where to start

1. <FTC powered via outdoor unit, LED1 also off>
2. Check the voltage across terminals L and N or L3 and N on the outdoor power board
3. If voltage not 220 to 240V AC, check wiring of outdoor unit and breaker