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Rheem · Furnace

3 blinks Limit circuit open

High severity Rheem (-)GRC/(-)GTC 90 PlusRheem 90RJ/90TJ 90 Plus

What the control is telling you

Green STATUS LED blinks 3 times: the limit circuit (main limit, rollout / overtemperature switches, or the aux. limit that the inducer wire passes through) is open or opening and closing.

Applies to: Rheem (-)GRC upflow and (-)GTC downflow/horizontal 90 Plus condensing gas furnaces (UT Electronic Controls 1012-925 / 1028-928 and Invensys ICC-H1MC7-01 IFC); Rheem 90RJ and 90TJ 90 Plus condensing gas furnaces (UT Electronic Controls 1012-925 or Invensys ICC-H1MC7-01 IFC, hot surface ignition)

Likely causes

  • Restricted airflow - dirty filter, closed dampers or registers
  • Over-firing - temperature rise above the rating plate range from high gas pressure or wrong orifices
  • Tripped manual-reset rollout / overtemperature switch from flame rollout (blocked flue or heat exchanger)
  • Loose wiring or connections between IFC and limits
  • Faulty limit

Test and repair steps

  1. Warning: Hazardous line voltage - disconnect power before servicing; work must be done by a trained, qualified service technician.
  2. Check airflow filter, dampers, closed registers and other restrictions.
  3. Measure temperature rise; if above the stated range, check gas valve, gas pressure and orifice size for over-firing.
  4. Check whether a rollout or overtemperature switch needs manual reset. WARNING: do not jumper these switches and do not reset one without finding and correcting the cause (inadequate combustion air, blocked flue or heat exchanger) - CO poisoning risk.
  5. Check the wiring and connections between the IFC and every limit, including the aux. limit wire through which the IDM is fed on 90+ units.
  6. Confirm limits are not open while circulating air temperature is within the normal range; replace only with the identical part.

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Source: Rheem (-)GRC/(-)GTC Installation Instructions 92-24161-88-00, Figure 56 IFC Troubleshooting Guide, p.54 (printed); Rheem 90RJ/90TJ Installation Instructions 92-24161-32-08, Figure 53 IFC Troubleshooting Guide, p.54 (printed p.53). Summarized in our own words; check the original manual for your model.

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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.