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MrCool Mini-Split F3 — Compressor Discharge Sensor (TP) Fault

MrCool Mini-Split · Error code F3

What F3 Means

F3 means the compressor discharge temperature sensor (TP thermistor) is open, shorted, or reading a dangerously high temperature. The unit protects the compressor by shutting down.

Symptoms

  • Outdoor unit stops
  • Poor heating/cooling
  • F3 on the display

Common Causes

1
Failed discharge thermistor

The TP sensor on the compressor has failed.

2
Low refrigerant charge

A low charge makes the compressor run hot, raising discharge temperature.

How to Fix It

  1. Power off and reseat the TP sensor connector on the outdoor board.
  2. If the unit was recently installed/charged, verify the refrigerant charge — low charge causes high discharge temps.
  3. Replace the sensor if faulty; a persistent high-temp trip needs a technician to check the charge and compressor.

Parts You May Need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

Common replacement Mini-Split Outdoor Sensor Kit View on Amazon→

More MrCool Mini-Split Codes

E1 E1 — Indoor/Outdoor Communication Error E2 E2 — Zero-Crossing Detection Error E3 E3 — Indoor Fan Speed Out of Control E4 E4 — Indoor Room Sensor (T1) Fault E5 E5 — Indoor Coil Sensor (T2) Fault F0 F0 — Overload / Current Protection

All MrCool codes → All mini-split codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.