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Carrier · Heat pump

77 Maximum power mode - compressor current

Medium severity Carrier Infinity 18VS 25VNA8

What the control is telling you

Amber STATUS light flashes 77. The compressor is outside its allowed operating range, so the inverter drops to a lower speed. Type: Local; reset: None.

Applies to: Carrier Infinity 18VS variable speed heat pump 25VNA8 (AOC control + inverter)

Likely causes

  • Cooling: Overcharged system
  • Heating: Overcharged system
  • Wrong refrigerant charge
  • Outdoor airflow too low or off
  • Supply voltage outside the rating plate range
  • Loose or wrong wiring to the compressor

Test and repair steps

  1. Cooling check subcooling in Charging Mode (or the subcooling chart on the control box door) and adjust charge.
  2. Heating compare pressures with the heating check chart; if they do not match, recover, evacuate and weigh in the rating plate charge.
  3. Check the outdoor coil and fan.
  4. Check supply voltage against the rating plate.
  5. Check power leads and the compressor plug connections.

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Source: Carrier 25VNA8 / 24VNA9 Service Manual, Table 6 Fault Code Actions, p.22. 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.