HVACopediaYork · Furnace
3 red flashes Pressure switch open when it should be closed
What the control is telling you
The (first-stage) pressure switch does not close after the inducer starts.
Applies to: York/JCI residential gas furnaces: York UTEC IFC furnaces, York White-Rodgers IFC furnaces, York TM9V
Likely causes
- Inducer motor failed or weak
- Blocked vent or intake pipe / termination
- Cracked, kinked or water-filled pressure switch hose
- Blocked condensate drain (condensing models)
- Loose or disconnected wires
- Faulty pressure switch
Test and repair steps
- Confirm the inducer starts and runs at speed.
- Inspect vent and intake pipes and terminations for blockage, ice, nests.
- Check the hose from the switch to the port - no cracks, kinks or water.
- Clear the condensate trap and drain on condensing models.
- Check switch wiring, then test the switch with a manometer against its rating; replace if bad.
- Warning: Never bypass or adjust a pressure switch to make the furnace run.
- To read stored codes with no thermostat call active, tap the LAST ERROR button briefly (under 5 s); up to five codes play back newest first. Two green flashes = memory empty. Hold the button 5 s or more to clear (three green flashes confirm).
Settings for these units
Clearance to combustibles · York TM9V
| Side of furnace | Upflow | Downflow | Horizontal |
|---|---|---|---|
| Top / vent / rear / side / front | ? | ? | ? |
| Combustible floor | Yes | Yes (special sub-base only) | Yes |
| Closet | Yes | Yes | Yes |
| Line contact | No | No | Yes |
Leave about 24 in. at the front and 18 in. at the side for service.
Approved for alcove and attic installs.
Filter size by return location · York TM9V
| Airflow | Cabinet | Side return filter | Bottom return filter |
|---|---|---|---|
| 1000 CFM | A | 16 x 25 in. | 14 x 25 in. |
| 1200 CFM | B | 16 x 25 in. | 16 x 25 in. |
| 1600 CFM | C | 16 x 25 in. | 20 x 25 in. |
| 2000 CFM | C | (2) 16 x 25 in. | 20 x 25 in. |
| 2000 CFM | D | (2) 16 x 25 in. | 22 x 25 in. |
Sizes assume high velocity filters (600 FPM); throwaway filters must stay at or below 300 FPM.
Filters go outside the cabinet - never inside the furnace.
Models that show this code
7 models in York UTEC IFC furnaces, York White-Rodgers IFC furnaces, York TM9V
Other codes on the same units
- 1 red flash Flame detected with gas valve off
- 2 red flashes Pressure switch closed when it should be open
- 3 amber flashes W2 call without W1
- 3 double red flashes Second-stage pressure switch not closing
- 4 amber flashes Cooling call (Y) without fan call (G)
- 4 red flashes Main limit switch open
- 5 red flashes Rollout switch open / limit circuit open over 15 min
- 6 red flashes Pressure switch cycling lockout
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Source: York All JCI single-two-stage furnaces with UTEC IFC board codes ST-045-09.pdf - section Fault Code LED Flashes; York JCI single-two-stage furnaces with White-Rodgers-Emerson IFC (older installed base) codes ST-028-07.pdf - section Fault Code Sheets; York TM9V - -M9V 96% two-stage variable speed installation 1083294-UIM-A-0114.pdf - section Furnace Control Diagnostics. 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.