Mitsubishi Error Code 3: Communication Error
Warning: Your Mitsubishi HVAC system has a communication error, which may cause it to stop working or function incorrectly. It's safe to operate, but you should schedule a professional repair soon.
LED Blink Pattern
LED blinks 3 times.
How to Fix Mitsubishi Code 3
- Check the batteries in your remote control and replace them if necessary
- Ensure that the remote control is within range of the indoor unit and not being obstructed
- Try resetting your HVAC system by turning it off and then back on again after a few minutes
- If the issue persists, contact a professional HVAC technician for repair
How to Reset Mitsubishi Code 3
- 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 Mitsubishi Error Code 3 Mean?
A communication error (error code 3) on your Mitsubishi HVAC system means that the indoor and outdoor units are not communicating properly with each other. This can happen due to a variety of reasons, such as a faulty communication wire, a problem with the control board, or an issue with the remote control. When this error occurs, your system may not function as intended, and you might notice that it's not heating or cooling your space effectively.
Common Causes
- Faulty communication wire between the indoor and outdoor units
- Problem with the control board in either the indoor or outdoor unit
- Issue with the remote control, such as low batteries or interference
- Dirty or damaged outdoor unit, causing poor communication with the indoor unit
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| The outdoor unit's LED is blinking rapidly | Measure the voltage between the R and Y terminals on the indoor unit's control board | 12-24 V AC |
| The voltage is within the expected range | Inspect the communication wire between the indoor and outdoor units for any damage or disconnection | No damage or disconnection |
Applicable Mitsubishi Models
- City Multi (VRF)(electric)
- City Multi (Y)(electric)
- Diamond (PJ)(electric)
- Diamond Plus(electric)
- Diamond Series(electric)
- Ducted Systems(electric)
- M-Series(electric)
- MSZ(electric)
- MSZ Series(electric)
- MSZ-AP(electric)
- MSZ-AP Series(electric)
- MSZ-AP5 Series(electric)
- MSZ-AS(electric)
- MSZ-FD(electric)
- MSZ-FE(electric)
- MSZ-FS(electric)
- MSZ-FS/FD Series(electric)
- MSZ-FT(electric)
- MSZ-FY(electric)
- MSZ-GE(electric)
- MSZ-LV(electric)
- MUZ-FE Series(electric)
- P-Series(electric)
- PUMA(electric)
- PUMY(electric)
- Puff (P-Series)(electric)
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Communication wire | — | — | — |
| Control board | — | — | — |
Related Codes on Same Models
Other codes that affect the same Mitsubishi model families as 3.
| Code | Description | Severity |
|---|---|---|
| 1 | Indoor/Outdoor Mismatch | Warning |
| 2 | Power Supply Phase Error | Warning |
| 4 | Inverter Error | Warning |
| 5 | Outdoor Thermistor Open/Short | Warning |
| 6 | Indoor Freeze/Overheat | Warning |
| 7 | Outdoor Freeze/Overheat | Warning |
| E6 | Indoor/Outdoor Communication Error | Warning |
| E9 | Indoor/Outdoor Communication Fault | Warning |
| P1 | Intake Sensor Error | Warning |
| P2 | Indoor Pipe Thermistor Error | Warning |