2 blinks Pressure switch circuit open

What the control is telling you

Green STATUS LED blinks 2 times: the air-proving (negative) pressure switch circuit did not close or opened while the inducer was running.

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

• Blocked vent or intake, or vent too long / too many elbows / too small
• Blocked heat exchanger
• Pressure switch hoses kinked, disconnected, or holding water
• Inducer (IDM) wired wrong, weak, or bad capacitor
• High wind opening the switch
• On downflow 90+ units, auxiliary limit open (inducer wire runs through it)
• Faulty pressure switch or wiring

Test and repair steps

1. Warning: Hazardous line voltage - disconnect power before servicing; work must be done by a trained, qualified service technician.
2. Confirm the inducer runs for the 30-second pre-purge; if not, check line voltage at the IDM, wires between IDM and IFC, line voltage on the IDM pins of the IFC connector, and the IDM capacitor (90+ only).
3. Check the pressure switch(es), hoses and wires; drain any water or moisture from switches and hoses.
4. Inspect vent and intake for blockage; verify vent length, number of elbows and pipe diameter are within the venting tables.
5. Check for a blocked heat exchanger.
6. Make sure the inducer is wired correctly and consider excessive wind at the termination opening the switch.
7. On downflow 90+ models check the auxiliary limit - it should be closed.
8. Watch for intermittent pressure switch operation during the ignition trial.

Settings for these units

Filter sizes (Table 12) · Rheem 90RJ/90TJ 90 Plus

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

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)
• 3 blinks Limit circuit open
• 4 blinks Pressure switch circuit closed (stuck closed)
• 5 blinks Twinning fault (optional)
• Flame LED off No flame sensed (troubleshooting aid)
• Flame LED rapid blink Amber flame LED - unexpected flame
• Flame LED slow blink Amber flame LED - marginal flame sense