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Gree · Heat pump

b2 Defrost (coil) sensor open or shorted (20K)

Medium severity Gree GMV6 Mini VRF

What the control is telling you

The defrost (coil) thermistor (20K, RT3, CN422) reads open or shorted.

Applies to: Gree GMV6 Ultra Heat Mini VRF 36-60k (GMV-V..WL/C-T(U))

Likely causes

  • Sensor or plug fault
  • Wire damage
  • Board fault

Test and repair steps

  1. Turn off power and reseat the sensor plug.
  2. Measure the sensor and compare with the 20K resistance chart in the appendix.
  3. Replace the sensor if out of range; if good, replace the board that reads it.

Models that show this code

3 models in Gree GMV6 Mini VRF

GMV-V36WL/C-T(U)GMV-V48WL/C-T(U)GMV-V60WL/C-T(U)

Other codes on the same units

  • A0 Waiting for commissioning (status)
  • b1 Outdoor ambient sensor open or shorted (15K)
  • b4 Sub-cooler liquid outlet sensor open or shorted (20K)
  • b6 Accumulator inlet sensor open or shorted (20K)
  • C0 Communication fault IDU/ODU/wired controller
  • C1 Main board to DC-DC controller communication fault
  • C2 Main board to compressor drive communication fault
  • C3 Main board to fan drive communication fault

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Source: Gree GMV6 Ultra Heat Mini VRF 36-60k (GMV-V36-48-60WL-C-T(U)) service.pdf - section Chapter 3 Faults, 4.1 Error Indication. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.