4 blinks Pressure switch circuit closed (stuck closed)

What the control is telling you

Green STATUS LED blinks 4 times: the pressure switch is closed when it should be open (e.g. before the inducer starts or after post-purge).

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

• Pressure switch contacts welded/stuck
• Short in pressure switch wiring
• Water or moisture in the switch or hoses
• Faulty IFC (only after other checks)

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 the pressure switch contacts with the inducer off - they should be open.
3. Check the switch wiring for a short.
4. Check the switches and hoses for water or moisture and clear it.
5. If the switch and wiring are good, check the IFC.

Settings for these units

• Filter sizes (Table 12) · Rheem 90RJ/90TJ 90 Plus
• Minimum clearance to combustibles · Rheem 90RJ/90TJ 90 Plus
• Filter sizes (Table 9) · Rheem (-)GRC/(-)GTC 90 Plus
• Minimum clearance to combustibles · Rheem (-)GRC/(-)GTC 90 Plus