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York 3 red flashes: The pressure switch contacts are open when they should be closed

Source: York manual (PDF) (opens in a new tab) ↗ · Updated

Status code3 red flashesYork
What does York 3 red flashes mean?

The pressure switch contacts are open when they should be closed.

Homeowner part this code names: furnace pressure switch hose.

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Call a pro: jump to when to call a pro Equipment type: furnace
How it shows: LED behind the blower-door view port on a York TG9S. Each flash is 1/3 second on and 1/3 second off, then a 2-second pause: 3 red flashes

York TG9S 3 red flashes means the pressure switch stayed open when it should have closed. The manual lists a faulty inducer, a blocked vent pipe, a broken pressure switch hose, disconnected pressure switch or inducer wires, and a faulty pressure switch. The outdoor pipe is the homeowner look. The hose, wires, inducer and switch are technician checks. Six red flashes is the same switch opening four times during a running cycle, then a one-hour lockout.

Likely causes

  • Faulty inducer
  • Blocked vent pipe
  • Broken pressure switch hose
  • Disconnected pressure switch or inducer wires
  • Faulty pressure switch

Safe checks for 3 red flashes

  1. Look at the outdoor vent pipe for snow, ice, leaves or a nest. Do not take the pipe apart
  2. Techniciancheck the inducer, the pressure switch hose, disconnected pressure switch or inducer wires, and the pressure switch
Safety firstIf you smell gas, do not touch any electrical switch or use a phone in the building; leave immediately and call your gas supplier from outside. Turn off electrical power at the furnace switch or breaker before opening any panel, and never bypass or jumper a limit, rollout or pressure switch. Gas valve, burner, venting, wiring and control-board work should be done by a licensed HVAC technician.

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

When to call a pro

Call a licensed HVAC technician if the vent pipe is clear and 3 red flashes continue. Do not jumper or adjust the pressure switch.

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Parts & tools for this fix

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Furnace pressure switch hose: guide

In this code: Broken pressure switch hose

Search: York furnace pressure switch hoseSearch: Furnace pressure switch tubing kitSearch: Furnace pressure switch hose, general search

Furnace pressure switch: guide

In this code: Broken pressure switch hose

This one is for a technician to test or replace, so we only explain it and do not link to buy it.

Furnace inducer (draft) motor: guide

In this code: Faulty inducer

This one is for a technician to test or replace, so we only explain it and do not link to buy it.

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Related York codes

10 red flashesThe gas valve is energized with2 red flashesThe pressure switch is closed when4 red flashesThe main limit switch has opened7 red flashesThe flame could not be established6 red flashesWhile the furnace was operating, the8 red flashesThe flame was lost five times

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