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Furnace pressure switch

What a furnace pressure switch proves, codes that point to it, why you should never jumper it, and how to choose a replacement.

Updated

What it is

The pressure (prove) switch tells the control board that the inducer is moving air through the vent. If it stays open, or closes when it should not, the board will not light the burners. It protects against venting failures that can put carbon monoxide in a home.

Manuals list blocked vent or intake pipes, a weak inducer, obstructed pressure tubing and condensate problems as common causes before the switch itself.

How to choose

  • Replacement switches are rated by the pressure at which they close, so the part number from your manual or the old switch matters more than how it looks.
  • Do not substitute a different pressure rating.
  • If the hose is cracked, replace it too (see the pressure switch hose guide).

How it is tested

  • Look at the outdoor intake and exhaust terminations for snow, ice, leaves or nests first.
  • Technicians check that the hoses are clear and whether the switch opens and closes with the inducer running; Carrier, Trane and Goodman all list the pressure switch among their checks.
  • Never jumper or bypass a pressure switch.

Replacing it

  • Replacement is a technician job on a gas furnace because the switch is part of the safety circuit and the vent must be proven afterwards.
Safety firstGas, venting, high-voltage and control-board work belongs to a licensed HVAC technician. This page is here so you can recognise the part and read a quote, not as a how-to for working on a gas appliance.

Capacitors can hold a charge after the power is off. Safety terms.

Where to buy

These are Amazon links. Product page links go to one specific listing whose title we read on Amazon; we do not say it fits your model. Search links open search results, which change. Always confirm your model number and the part number in your manual.

Searches by type or size

Search: Furnace pressure switch, general searchSearch: Replacement furnace inducer pressure switch

Searches by brand

Search: Amana furnace pressure switchSearch: American Standard furnace pressure switchSearch: Bryant furnace pressure switchSearch: Carrier furnace pressure switchSearch: Goodman furnace pressure switchSearch: Lennox furnace pressure switchSearch: Rheem furnace pressure switchSearch: Trane furnace pressure switchSearch: York furnace pressure switch

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Codes that mention it

Error codes whose own causes or steps name this part or check.

Amana

Amana EE0Amana EE2Amana EE8Amana EE9

American Standard

American Standard E09American Standard E3.1American Standard E3.4American Standard E6.3American Standard E3.2

Bryant

Bryant 23Bryant 31Bryant 32Bryant 43

Carrier

Carrier 23Carrier 31

Goodman

Goodman EE0Goodman EE1Goodman EE2

Lennox

Lennox E223Lennox Red off, green slow flash

Rheem

Rheem 33Rheem 44Rheem 45Rheem 46Rheem 55Rheem 57

Trane

Trane E3.1Trane E3.2Trane E3.3Trane E3.4

Per-brand lists: Amana furnace · American Standard furnace · Bryant furnace · Carrier furnace · Goodman furnace · Lennox furnace · Rheem furnace · Trane furnace · York furnace.

Sources