HVACopediaRheem · Furnace
Flame LED off No flame sensed (troubleshooting aid)
What the control is telling you
Amber FLAME LED off while burners are visibly lit means the flame is not being sensed (it should be steady ON when burners are lit). Off with no heat call is normal.
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
- Dirty flame sensor
- Poor ground or reversed polarity
- Open flame sensor wire
- Burners not actually lighting
Test and repair steps
- Confirm burners are lit during the ignition trial.
- Clean the flame sense rod and check its wire to the IFC.
- Check IFC/unit ground and L1/Neutral polarity.
- If the control still cannot see flame it will retry and go to soft lockout (1 blink) after 4 attempts - follow the 1-blink steps.
Settings for these units
Filter sizes (Table 12) · Rheem 90RJ/90TJ 90 Plus
| Configuration | Cabinet width | Input (MBTU/h) | Bottom filter | Side filter | Qty |
|---|---|---|---|---|---|
| Upflow | 17-1/2 in. | 45, 60, 75 | 15-3/4 x 25 in. | 15-3/4 x 25 in. | 1 |
| Upflow | 21 in. | 90, 105 | 19-1/4 x 25 in. | 15-3/4 x 25 in. | 1 |
| Upflow | 24-1/2 in. | 120 | 22-3/4 x 25 in. | 15-3/4 x 25 in. | 1 |
| Downflow | 17-1/2 in. | 45, 60, 75 | 12 x 20 in. | - | 2 |
| Downflow | 21 in. | 90, 105 | 12 x 20 in. | - | 2 |
| Downflow | 24-1/2 in. | 120 | 14 x 20 in. | - | 2 |
Filters are not factory-installed; they must be field supplied.
Side filter on 21 in. units: cut 3.5 in. off the filter and frame; on 24.5 in. units cut 7 in.
Minimum clearance to combustibles · Rheem 90RJ/90TJ 90 Plus
| Configuration | Left side | Right side | Back | Top | Front | Vent |
|---|---|---|---|---|---|---|
| Upflow | 0 in. | 0 in. | 0 in. | 1 in. | 2 in. (24 in. service) | 0 in. |
| Downflow | 0 in. | 0 in. | 0 in. | 1 in. | 2 in. (24 in. service) | 0 in. |
| Horizontal | 0 in. | 0 in. | 0 in. | 1 in. | 2 in. (24 in. service) | 0 in. |
Same values for every cabinet size.
24 in. service clearance recommended in front of all furnaces.
- Filter sizes (Table 9) · Rheem (-)GRC/(-)GTC 90 Plus
- Minimum clearance to combustibles · Rheem (-)GRC/(-)GTC 90 Plus
Models that show this code
23 models in Rheem (-)GRC/(-)GTC 90 Plus, Rheem 90RJ/90TJ 90 Plus
Other codes on the same units
- 1 blink Soft lockout (failed ignition)
- 2 blinks Pressure switch circuit open
- 3 blinks Limit circuit open
- 4 blinks Pressure switch circuit closed (stuck closed)
- 5 blinks Twinning fault (optional)
- Flame LED rapid blink Amber flame LED - unexpected flame
- Flame LED slow blink Amber flame LED - marginal flame sense
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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.
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.