Fujitsu Error Code E3:00: Room Temp Sensor Short Circuit
How to Fix Fujitsu Code E3:00
- Step 1: Power cycle the unit by turning it off at the breaker for 5 minutes, then turn it back on. This may reset a temporary glitch.
- Step 2: Visually inspect the area around the indoor unit for any signs of obvious damage to the unit casing or any exposed wiring.
- Step 3: If the error persists after power cycling, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Fujitsu Code E3:00
- 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 E3:00 Mean?
The E3:00 error code on your Fujitsu mini-split indicates a problem with the room temperature sensor. This sensor is responsible for accurately measuring the temperature in your room and communicating that information back to the unit's control board. The control board uses this data to regulate heating and cooling output. A 'short circuit' means there's an unintended electrical connection, likely caused by damaged wiring or a faulty sensor. Because the system can't reliably read the room temperature, it shuts down to prevent potential problems like overheating or inefficient operation. This isn't a dangerous situation like a gas leak, but it does mean your mini-split won't work until the problem is fixed. It's important to address this promptly to restore your heating or cooling.
Common Causes
- Faulty room temperature sensor
- Wiring damage (short circuit) between the sensor and the control board
- Loose or corroded connections at the sensor or control board
- Moisture intrusion affecting the sensor or wiring
- Control board malfunction
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Unit displays E3:00 error | Disconnect the room temperature sensor from the control board and measure the resistance across the sensor terminals. | Should read a specific resistance value at room temperature (refer to Fujitsu service manual for the exact value, typically around 10k ohms at 25°C). A reading of 0 ohms or very close to 0 indicates a short circuit. |
| Sensor resistance is incorrect | Inspect the wiring harness and connectors between the sensor and the control board for any signs of damage, shorts, or corrosion. | Wiring and connectors should be intact and free of corrosion. |
| Wiring appears OK | Check the voltage at the control board terminals where the room temperature sensor connects (with the sensor disconnected). | Should read a low DC voltage, typically around 5V DC. Consult the Fujitsu service manual for the exact voltage. |
| Voltage is absent or incorrect | Check the control board for any signs of damage, such as burnt components or corrosion. | Control board should appear undamaged. |
Applicable Fujitsu Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Room Temperature Sensor | — | — | — |
| Control Board | — | — | — |
| Wiring Harness | — | — | — |
Related Codes on Same Models
Other codes that affect the same Fujitsu model families as E3:00.
| Code | Description | Severity |
|---|---|---|
| E0:00 | Communication Error (Indoor to Remote) | Warning |
| E1:00 | Communication Error (Indoor to Outdoor) | Warning |
| E2:00 | Room Temp Sensor Open 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 |