Maheshwari HVACAC & HVAC experts · Udaipur

Midea AC error codes – Multi-split indoor - Console series

10 codes from the Midea service manual, with what each one means and the usual causes. Read Operation / Timer / Defrost lamps. ✱ fast flash, ◎ slow flash, ● on, ○ off.

You can safely switch the unit off at the switch, wait 5 minutes and switch on again. Don't open the unit, touch wiring or handle gas: these checks need a trained technician.

Op✱ T○ D○

T1 room sensor open/short

Usual causes

  • Sensor connector loose
  • Sensor open or short
  • PCB input circuit fault
What our technician checks
  • Check sensor-to-PCB connection
  • Measure sensor resistance against table. Sensor table (Appendix 1, T1/T2/T2B/T3/T4): 10 kΩ at 25°C, 12.64k at 20°C, 7.97k at 30°C, 5.18k at 40°C, 35.2k at 0°C
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Op○ T○ D✱

T2 coil sensor open/short

Usual causes

  • Sensor connector loose
  • Sensor open or short
  • PCB input circuit fault
What our technician checks
  • Check sensor-to-PCB connection
  • Measure sensor resistance against table. Sensor table (Appendix 1, T1/T2/T2B/T3/T4): 10 kΩ at 25°C, 12.64k at 20°C, 7.97k at 30°C, 5.18k at 40°C, 35.2k at 0°C
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Op○ T✱ D○

Indoor / outdoor communication error

Usual causes

  • Wrong / loose wiring between indoor and outdoor terminals
  • Signal line S fault
  • IPM or PFC board not powered (multi outdoor)
  • Reactor disconnected
  • Wrong number of indoor units detected
  • Indoor or outdoor PCB fault
What our technician checks
  • Power off at breaker, power on again
  • Check wiring follows the wiring diagram
  • Measure Vs (voltage between S and L2/N): it should swing between positive and negative
  • With all indoors off, check IPM power LED on and PFC LED (qua-zone)
  • Outdoor check button: press 18 times to see how many indoor units are detected (2 dual, 3 tri, 4 quad)
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Op✱ T✱ D○

Indoor EEPROM malfunction

Usual causes

  • EEPROM chip loose (socket type)
  • Indoor PCB faulty
What our technician checks
  • Switch off 1 minute, switch on
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Op✱ T○ D✱

IPM module protection

Usual causes

  • IPM P-N voltage wrong (needs 277-356 V DC for 14-27K, 277-410 V DC for 36K)
  • Supply not 220-240 V
  • Loose cable main board-IPM
  • Compressor leads loose / wrong
  • Bridge rectifier shorted
  • Reactor wire broken (∞ Ω) or PFC module faulty (M5OA-36)
  • IPM module, main board or compressor faulty
What our technician checks
  • Measure P-N on IPM
  • Check supply voltage and wiring
  • Check cable main board-IPM and compressor connections
  • Measure bridge rectifier: no terminal pair should read 0 Ω
  • Measure reactor: open (∞) = broken
  • Compressor phase-phase U-V, U-W, V-W 60-150 V AC when running
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Op✱ T✱ D✱

T3 or T4 outdoor sensor open/short

Usual causes

  • Sensor connector loose
  • Sensor open or short
  • PCB input circuit fault
What our technician checks
  • Check sensor-to-PCB connection
  • Measure sensor resistance against table. Sensor table (Appendix 1, T1/T2/T2B/T3/T4): 10 kΩ at 25°C, 12.64k at 20°C, 7.97k at 30°C, 5.18k at 40°C, 35.2k at 0°C
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Op✱ T● D○

Compressor top temperature protection

Usual causes

  • Compressor not running / wiring loose
  • Low refrigerant
  • Compressor top overload protector faulty
  • Capillary / pipe blockage
  • Outdoor main PCB fault
What our technician checks
  • Is the compressor running? check connections
  • Check refrigerant circulation (pressures)
  • Check overload protector continuity
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Op✱ T◎ D○

Inverter compressor drive protection

Usual causes

  • Same as IPM protection: supply, P-N voltage, IPM, compressor, reactor
What our technician checks
  • Follow IPM module protection checks
Book a technician for Op✱ T◎ D○

Op✱ T○ D●

Mode conflict

Usual causes

  • Indoor units of the multi system set to conflicting modes (one cooling, one heating)
What our technician checks
  • Check modes on all indoor units
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Op✱ T● D✱

Indoor fan speed out of control

Usual causes

  • Cross-flow fan stuck or bearing worn
  • Fan motor wiring loose
  • Fan motor winding fault
  • Indoor PCB drive fault
What our technician checks
  • Power off 1 minute, restart
  • Turn the cross-flow fan by hand - should spin freely
  • Disconnect fan from motor and check bearing
  • Check motor wires and motor resistance
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Code not here, or still showing?

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