Midea AC error codes – Multi-split indoor - Ceiling & Floor series
10 codes from the Midea service manual, with what each one means and the usual causes. No digital code - read the lamps: Op = Operation, T = Timer, D = Defrost, A = Alarm. ✱ 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○ A○
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
Op○ T○ D✱ A○
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
Op○ T✱ D○ A○
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)
Op○ T○ D○ A✱
Full-water (drain) malfunction
Usual causes
- Water-level (float) switch not plugged in
- Float switch broken
- Drain pump faulty / drain blocked
- Indoor PCB fault
What our technician checks
- Check float switch connector
- Check float switch continuity
- Check drain pump runs and drain line is clear
Op✱ T✱ D○ A○
Indoor EEPROM malfunction
Usual causes
- EEPROM chip loose (socket type)
- Indoor PCB faulty
What our technician checks
- Switch off 1 minute, switch on
Op✱ T○ D○ A●
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
Op✱ T● D○ A○
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
Op✱ T● D○ A●
Outdoor voltage protection
Usual causes
- Supply voltage wrong (should be about 220 V AC, unit works 190-264 V)
- Power board fault
- Bridge rectifier fault
- IPM board fault
What our technician checks
- Measure outdoor L-N: about 220 V AC
- Measure IPM board P-N: 280-400 V DC
- Rectifier: input 220-230 V AC gives about 310 V DC
Op✱ T○ D● A○
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
Op✱ T○ D● A●
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
Code not here, or still showing?
Send a photo of the display and the model sticker on WhatsApp. We'll tell you what it means and whether it needs a visit.
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