York ductless AC shows d2 and may short cycle or not defrost properly

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Failed outdoor coil thermistor, Sensor not attached to coil, Damaged sensor wiring, Faulty outdoor PCB

Safety: Disconnect power at the outdoor disconnect before opening the condensing unit.

Locate coil sensor: Find the thermistor clipped to the outdoor coil tubing. Ensure it is firmly attached and not dangling.
Inspect wiring: Check for rodent damage or pulled wires between the sensor and the outdoor board.
Test thermistor: Measure resistance and compare to York's temperature‑resistance chart. Replace if out of range.
Replace outdoor PCB: If sensor and wiring are good but d2 persists, the outdoor control board may be defective.

Medium 3/5

Outdoor Coil Temperature Sensor

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