What does "pressure switch stuck open" actually mean?

The board energised the inducer and then waited for the switch to close, and it never did. Before replacing the switch, check the obvious causes: a blocked or cracked hose, a plugged inducer port, a blocked or iced-over vent termination, a full condensate trap, or a failing inducer that no longer pulls its rated draft. The switch is frequently the messenger, not the fault.

What about "pressure switch stuck closed"?

The board found the switch already closed before the inducer started, so it cannot verify the safety. That usually means welded contacts inside the switch — a genuine replacement case — or a hose left connected to the wrong port.

Does the pressure rating on the switch matter?

Yes, and it is the number to match. Switches are rated in inches of water column — for example −0.40" WC — and that setpoint is chosen for your specific furnace and vent configuration. A switch with the wrong rating either nuisance-trips or fails to protect you. Match the rating stamped on the old switch, not just the physical shape.

Furnace Pressure Switches

A pressure switch is a safety interlock that proves the draft inducer is actually moving air before the control board will open the gas valve. It senses the negative pressure the inducer creates through a small hose; no vacuum, no gas. Most "stuck open" faults are not the switch at all — they are the switch correctly reporting a venting problem.

487 pressure switches in stock, ready for same-day pickup at our Coquitlam warehouse or shipped worldwide. Homeowners and contractors buy at the same counter — no trade account needed.

Signs your pressure switche may have failed

Inducer runs, then everything stops before the ignitor glows
Control board reports pressure switch stuck open, or stuck closed
Failure is intermittent and worse in wind, rain, or hard frost
Water visible in the pressure hose or the inducer port

Not sure which part you need? Call 1-778-759-9864 with your furnace model number and we will confirm it before you order.

Troubleshooting guides

Why Won't My Furnace Ignite?A Practical Guide to Common Causes and Checks Your Furnace Sequence of OperationUnderstanding How Your Gas Furnace Starts and Runs Furnace Starts Then Shuts OffCommon Causes of Short Cycling and Early Shutdown Blocked Furnace FiltersIrreversible Damage Risk Pressure Switch Stuck ClosedWhy Your Furnace Shows an Error Code and Will Not Start Pressure Switch Stuck OpenWhy Your Furnace Will Not Start the Heating Sequence Furnace Shuts Down Then Restarts After 1 to 3 HoursUnderstanding Furnace Lockout and Why It Happens

Shop pressure switches by brand

Lennox141 York109 Carrier78 Goodman73 American Standard64 Ruud36

Signs your pressure switche may have failed

Troubleshooting guides

Shop pressure switches by brand

Pressure Switches we stock

LENNOX SWITCH, LOW PRESSURE

LENNOX SWITCH, LOW PRESSURE

LENNOX PRESSURE SWITCH, LOW AMBIENT, OPENS 150F, CLOSES 275F

LENNOX TUBING KIT, PRESSURE SWITCH, BLACK &AMP; RED

LENNOX HIGH PRESSURE SWITCH, ACTUATES AT 410 PSI; MANUAL RESET

LENNOX SWITCH - PRESSURE

LENNOX TUBING, PRESSURE SWITCH

LENNOX SWITCH, HIGH PRESSURE, 450/300

102448-01 SWITCH-HIGH PRESSURE (640PSI)

Pressure Switch, 1.25" Water Column, SPST

Airswitch Safety Interlock Pressure Switch, SPST, Normally Open

LOSS OF CHARGE PRESSURE SWITCH, ACTUATES AT 55 PSI; RESETS AT 25 PSI

Switch, High Pressure, Cutout 450, Manual Reset

Pressure Switch, 0.47" WC, SPST

High Pressure Switch, Actuates at 640 PI/Resets at 475 PSI, SPST, Normally Closed

LENNOX SWITCH, HIGH PRESSURE, 120/240V, MANUAL RESET

LENNOX SWITCH, HIGH PRESSURE, 590 # CUTOUT, MANUAL RESET

LENNOX PRESSURE TRANSDUCER

LENNOX SWITCH-PRESSURE (LOW FIRE) 1.35"WC

LENNOX PRESSURE SWITCH TUBING KIT

SWITCH; PRESSURE, SPST 0.90"WC

SWITCH; HIGH PRESSURE, BRAZED, SPST, OPE

SWITCH; PRESSURE-.70

SWITCH; PRESSURE-.65

Pressure Switch, Dual, 0.50"WC/0.17"WC

SWITCH, PRESSURE, OPEN AT -1.51 WC,

Air Pressure Control Switch, SPST, 0.20" WC

SWITCH PRESSURE

LENNOX SWITCH, PRESSURE - YK-4.4

SWITCH; HIGH PRESSURE, SPST, OPEN @ 650

SWITCH; LOW PRESSURE, OPEN @ 50 PSIG, CL

SWITCH; LOW PRESSURE, OPENS AT 35 PSI AN

SWITCH; PRESSURE-.72

CONTROL, AIR PRESSURE, -.45 IN WC OPEN,

SWITCH,DIFFERENTIAL PRESSURE, SPDT, 32-1

SWITCH PRESSURECUTOUT 120240 VAC - 1

SWITCH DIFFERENTIAL PRESSURE -40 TO 15

SWITCH, AIR FLOW

SWITCH SPDT 25AMP 277V PRESSURE

SWITCH, SPDT, 22 AMPS, 480V, PRESSURE

SWITCH PRESSURE SPDT 300 VA AT 120-27

SWITCH; CONTROL, LOW PRESSURE, 8 OPEN, 2

SWITCH HIGH PRESSURE CUTOUT 800 PSIG

SWITCH, LOW PRESSURE 25 OP/41 CL

SWITCH; LOW PRESSURE, OPEN @ 50 PSIG CLO

SWITCH, HIGH PRESSURE, BRAZED, OPENS AT

SWITCH; HIGH PRESSURE, SPST, OPEN @ 650

SWITCH; HIGH PRESSURE SPST OPEN @ 650

Pressure Switches questions

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