Daikin Split AC Error Code 00 signals a communication breakdown between the indoor unit and outdoor unit. Technicians clear the fault by verifying interconnect wiring continuity and confirming stable voltage at both terminal blocks.
Power cycle the entire system after each check to reset the control boards before advancing to component testing.
Daikin 00 Cable Voltage Inspection Steps
Daikin split systems display error code 00 when the indoor control board loses reliable data exchange with the outdoor board. This condition appears after power fluctuations or when the interconnect cable develops an open circuit. Field data shows the code triggers most often on units older than seven years that lack recent maintenance. Technicians begin every call with a visual inspection of the cable route and a voltage measurement at the terminals. These steps isolate wiring issues from board failures in under ten minutes.
| Symptom | Primary Suspect | Difficulty 1-5 |
|---|---|---|
| No cooling with code 00 | Interconnect cable break | 2 |
| Intermittent operation | Loose terminal screws | 1 |
| Complete shutdown | Outdoor PCB fault | 4 |
| Fan runs but compressor silent | Signal voltage drop | 3 |
Daikin Error 00 Interconnect Corrosion Checks
The error originates from missing or corrupted signals traveling across the four-wire interconnect between units. Voltage must remain between 12 and 24 volts DC on the communication line during operation. Corrosion at the outdoor terminal block interrupts this signal and forces the indoor board to post code 00. Technicians confirm the fault by disconnecting power then measuring resistance across each conductor. Values above 2 ohms indicate a damaged section that requires replacement.
Daikin Split AC Code 00 Reset Steps
Isolate power at the main breaker before touching any wiring.
Remove the access panels on both indoor and outdoor units.
Inspect each terminal for tightness and clean oxidation with electrical contact cleaner.
Test continuity on the communication wires with a multimeter set to ohms.
Restore power and observe whether code 00 clears within three minutes.
Monitor signal voltage while the compressor attempts to start.
A single sentence warning applies here. Never bypass the communication line with jumper wires because this action damages both control boards.
Daikin Split AC Indoor PCB Voltage Checks
Control boards inside the indoor unit supply the reference voltage that the outdoor board expects. Low voltage at the S terminal usually traces to a failing transformer or a cracked solder joint on the PCB. Measure DC voltage between terminals S and N while the system tries to run. Readings below 10 volts require board replacement rather than further cable checks. Replacement boards must match the exact model series to maintain proper protocol timing.
Daikin Error 00 Outdoor Fan Motor Test
The outdoor fan motor draws power through a relay on the outdoor PCB and shares the same communication bus. A seized motor can pull excessive current and collapse the signal line voltage. Disconnect the motor leads and spin the blade by hand to check for binding. Apply 220 volts directly to the motor windings only after confirming the capacitor tests within tolerance. Normal motors reach rated RPM within two seconds of power application.
Daikin Error 00 Pressure Switch Checks
Low refrigerant charge sometimes mimics communication faults because the outdoor board monitors pressure switches tied to the same data line. Connect gauges to the service ports and compare readings against the nameplate specifications. Pressures more than 15 percent below target require leak repair before any board replacement. Evacuate and recharge the circuit only after confirming the communication error has cleared.
Daikin Error 00 Thermistor Resistance Tests
Temperature sensors on the indoor coil and outdoor ambient provide data that the boards cross-check during startup. An open thermistor circuit produces code 00 because the control logic treats missing data as a communication loss. Unplug each sensor and measure resistance at room temperature. Values outside 5 to 20 kilohms indicate replacement. Install new sensors with dielectric grease on the connectors to prevent future corrosion.
Daikin Split AC Outdoor PCB Replacement
Persistent code 00 after cable and sensor replacement points to a failed outdoor PCB. Order the correct board using the unit serial number and schedule a certified technician for installation. This step restores full system communication and prevents repeated board damage from underlying wiring issues.
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