When an issue arises with a Hitachi air conditioner, an error code will display on the indoor unit indicator lights, wired remote controller, or LED panel. The code prefix helps identify the system component or circuit at fault:
- 00 Series: Indoor unit circuit and sensor faults
- 10 Series: Outdoor unit electrical, compressor, and inverter protection
- 20 Series: Pressure, temperature, and refrigeration cycle issues
- 30 Series: Communication and control transmission errors
1. How to Read & Reset Your Hitachi Display
- Locate the Error Code: Check the digital remote controller screen, or count the blinking sequence of the Timer/Run LEDs on the indoor front panel.
- Switch Off Main Power: Shut off the air conditioner using the main wall switch or circuit breaker (do not rely solely on the remote control).
- Wait 5 Minutes: Keep the system completely powered down for 5 minutes to allow the capacitors to discharge and system memory to reset.
- Power Back On & Test: Turn the main breaker back on and restart the unit. If the same error code reappears immediately or within a few minutes, an active hardware fault is present and requires repair.
2. Hitachi Error Code Reference Table
| Code | Meaning / Likely Cause | Severity | Recommended Action | Typical SG Cost |
| 01 | Activation of Protection Device (Indoor Unit) | Medium | Inspect indoor float switch, drain pan, or water pump failure. | $90 – $180 |
| 02 | Activation of Protection Device (Outdoor Unit) | High | Check outdoor high-pressure switch, fan obstruction, or dirty coils. | $130 – $250 |
| 03 | Communication Transmission Fault (Indoor-Outdoor) | High | Inspect wiring connections between indoor/outdoor units or PCB. | Diagnostic – $450 |
| 04 | Communication Fault (Inverter to Main Outdoor PCB) | High | Check inverter board connections, signal wiring, or replace PCB. | $300 – $600 |
| 05 | Power Phase Fault / Reverse Phase | High | Check power supply phases and incoming line wiring (3-phase systems). | Diagnostic visit |
| 08 | Compressor Top Temperature Overheat | High | Inspect refrigerant charge level; check for thermal expansion valve blockage. | From $180 |
| 11 | Indoor Intake Air Thermistor Fault | Medium | Test and replace defective indoor air inlet temperature sensor. | From $130 |
| 12 | Indoor Outlet Air Thermistor Fault | Medium | Inspect and replace indoor discharge air temperature thermistor. | From $130 |
| 13 | Indoor Freeze Protection Thermistor Fault | Medium | Clean indoor filters; replace evaporator thermistor if defective. | From $130 |
| 14 | Gas Pipe Thermistor Fault | Medium | Replace indoor/outdoor gas pipe pipe-temperature sensor. | From $130 |
| 21 | High Pressure Sensor Fault | High | Check outdoor fan operation, clean condenser coil, or replace sensor. | $130 – $250 |
| 22 | Low Pressure Protection / Gas Leak | High | Perform nitrogen pressure test, seal leak point, and recharge gas. | From $180 |
| 31 | Incorrect Capacity / Model Setting Code | Medium | Re-configure dip switches on PCB or replace EEPROM chip. | $130 – $300 |
| 35 | Indoor Unit Number Setting Error | Medium | Check central controller addressing and multi-split DIP switch settings. | Diagnostic visit |
| 38 | Outdoor Unit Protection Circuit Fault | High | Inspect outdoor control board current detection circuit or replace PCB. | $300 – $600 |
| EE | Compressor Protection / Hardware Failure | High | Immediately power down; check compressor windings, driver board, or IPM. | $350 – $750+ |
3. DIY vs. Professional Repair Matrix
🛑 WARNING: Running your Hitachi unit continuously with active high-severity error codes (such as 02, 04, 08, 22, or EE) can result in total compressor failure, motor burnout, or fried inverter boards.
🟢 Safe to DIY / Self-Check:
- 01 / 13 (Filter & Drain Checks): Clean or wash the indoor air filters, inspect the visible drain pipe outlet for clogs, and clear any debris.
- 03 (Isolator Check): Ensure the outdoor unit isolator switch is turned ON and not tripped at the distribution board.
- Hard Power Reset: Perform a 5-minute main power isolation reset to clear transient power line glitches or signal noise.
🔴 Requires Professional Repair:
- Sensor & Thermistor Replacement (11–14, 21): Requires multimeter resistance testing and physical component replacement.
- Refrigerant Leaks & Pressure Failures (08, 22): Demands nitrogen pressure testing, leak soldering, system vacuuming, and gas recharging.
- Electrical & Inverter Board Faults (04, 05, 38, EE): Involves high-voltage board diagnostics, IPM module repair, DIP switch programming, or compressor replacement.
