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Rheem · Heat pump

1 flash (L terminal) L-terminal fault output: Long run cycle or low pressure

Medium severity Rheem/Ruud PRL-JEC heat pump (Comfort Control2 ICC)

What the control is telling you

Compressor running an extremely long cycle or low pressure. Equivalent to 7-segment codes 01 / 21. Shown on an L-terminal compatible conventional thermostat when the unit is wired 24VAC (non-communicating).

Applies to: (-)PRL-JEC 2-stage 16 SEER heat pumps: RPRL/UPRL-024JEC, -036JEC, -048JEC, -060JEC

Likely causes

  • Low charge
  • Dirty filter or coil
  • Duct leakage
  • Frozen coil

Test and repair steps

  1. Read the 7-segment display on the ICC for the exact code.
  2. Check filter, coils, fans and charge (see codes 01 and 21).

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Source: Rheem (-)PRL-JEC Heat Pump Installation Instructions, 12.7 Conventional 24VAC Thermostat Control Wiring (L terminal output), p.31. 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.