U3 🟡 Repair Required
Mitsubishi Error Code U3: Discharge Thermistor Short/Open
⚠️ Your Mitsubishi HVAC system has detected a potential issue with the discharge thermistor, which could lead to system damage if not addressed.
How to Fix Mitsubishi Code U3
- Turn off your HVAC system at the thermostat and the circuit breaker to prevent further system operation.
- Contact a professional HVAC technician to diagnose and repair the issue.
What Does Mitsubishi Error Code U3 Mean?
The U3 error code on your Mitsubishi HVAC system indicates a problem with the discharge thermistor. This component measures the temperature of the air leaving your system, helping to maintain optimal cooling and heating. If the thermistor is shorted or open (not functioning), your system can't accurately monitor this temperature, leading to inefficient operation and potential system damage. Your system has entered a lockout mode to prevent further issues.
Common Causes of Mitsubishi Code U3
- Faulty discharge thermistor
- Wiring issue between the thermistor and the control board
- Control board failure
Applicable Mitsubishi Models
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Discharge Thermistor OEM: Mitsubishi 42903-00-00