Fujitsu Error Code E1:00: Communication Error (Indoor to Outdoor)
How to Fix Fujitsu Code E1:00
- Step 1: Check the power to both the indoor and outdoor units. Make sure both are turned on and receiving power.
- Step 2: Inspect the wiring connections at the outdoor unit disconnect. Ensure the wires are securely connected. (Note: Only inspect, do not touch any wires.)
- Step 3: If the problem persists, contact a qualified HVAC technician to diagnose and repair the communication issue.
How to Reset Fujitsu Code E1:00
- Turn off the unit using the remote control or wall controller.
- Turn off the circuit breaker for the outdoor and indoor units. Wait 60 seconds.
- Restore power at the breaker.
- Turn the unit on with the remote control. If the error returns, the fault needs professional diagnosis.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Fujitsu Error Code E1:00 Mean?
The E1:00 error code on your Fujitsu mini-split indicates a communication problem between the indoor unit and the outdoor unit. Essentially, the two units aren't talking to each other properly. This prevents the system from operating because the indoor unit can't tell the outdoor unit what to do (like turn on the compressor or adjust fan speed), and the outdoor unit can't report its status back to the indoor unit. This communication issue can stem from several things, ranging from simple wiring problems to more complex failures in the control boards of either the indoor or outdoor unit. Because mini-splits rely on constant communication to modulate their output and maintain efficient operation, this error will lock out the system until the problem is resolved. It's important to address this promptly to avoid further potential damage to the system components.
Common Causes
- Loose or damaged wiring between the indoor and outdoor units
- Faulty communication board in the indoor unit
- Faulty communication board in the outdoor unit
- Power surge or electrical interference affecting the communication signal
- Incorrect wiring during initial installation or previous service
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| No communication between indoor and outdoor units | Measure voltage at the communication terminals on both the indoor and outdoor units | 24V DC (or specified voltage per Fujitsu service manual) |
| Low or no voltage at communication terminals | Inspect the communication wiring for breaks, shorts, or loose connections | Wiring is intact and properly connected |
| Wiring appears intact | Check the resistance of the communication wire | Low resistance (close to 0 ohms) |
| Voltage present at both units | Check the grounding connection at both the indoor and outdoor units | Solid ground connection (less than 1 ohm to ground) |
Applicable Fujitsu Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Indoor Unit Control Board | — | — | — |
| Outdoor Unit Control Board | — | — | — |
| Communication Wire | — | — | — |
Related Codes on Same Models
Other codes that affect the same Fujitsu model families as E1:00.
| Code | Description | Severity |
|---|---|---|
| E0:00 | Communication Error (Indoor to Remote) | Warning |
| E2:00 | Room Temp Sensor Open Circuit | Warning |
| E3:00 | Room Temp Sensor Short Circuit | Warning |
| E4:00 | Indoor Coil Sensor Open | Warning |
| E5:00 | Indoor Coil Sensor Short | Warning |
| E6:00 | Outdoor Coil Sensor Fault | Warning |
| E7:00 | Outdoor Ambient Sensor Fault | Warning |
| E8:00 | Indoor Fan Motor Fault | Warning |
| E9:00 | Drain Pump / Float Switch | Warning |
| EE:00 | Communication Error (Multi-System) | Warning |