MrCool · Mini-Split Moderate

F2 — Outdoor Coil Sensor (T3) Fault

F2 means the outdoor condenser coil temperature sensor (T3 thermistor) is reading open or shorted.

Keep using it?
Yes, with caution
DIY difficulty
Hard
Typical cost
$15-30
Verified against
support.mrcool.com ↗

The fix

MrCool outdoor unit condenser coil temperature sensor

Condenser coil temperature sensor (T3 thermistor) open or shorted

$15-30 moderate difficulty 30-45 min Tools: screwdriver, multimeter

Diagnose first: Same DIY-replaceable sensor family as F1 — inspect the connector before ordering a replacement.

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How to fix it

  1. Power-cycle at the breaker: off for five minutes, back on.
  2. If F2 returns, call an HVAC technician. The coil sensor is attached to the condenser coil inside the outdoor cabinet — panel-open, technician territory.
  3. What the technician will do: test the T3 sensor against specification and replace it if failed. It is a small part; the visit is mostly access and confirming nothing else drove the reading out of range.

Why it happens

Typical signs: Reduced performance or shutdown · F2 on the display

  • Failed T3 coil sensor The condenser coil thermistor has failed.
  • Loose connector The T3 plug on the outdoor board is loose.

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. Verified against manufacturer documentation: support.mrcool.com.