Furnace High Pressure Switch Stuck Open

After all this the furnace should fire right back up.

Furnace high pressure switch stuck open.

This might free the switch from sticking. If you have 24 volts the pressure switch is open and not proving the ventor motor. Pushing in the plunger closes the circuit to activate the blower motor so if the switch is stuck in the open position that means the motor will not run. On a few furnaces i have found the ventor motor seams to be running fine and power is good but fails on pressure switch.

Tapping lightly on the pressure switch body may open the switch and the unit may start. Using a cloth and a wire brush remove any blockages and dirt from the secondary exchanger and the inducer. Take off the end so you can blow through it to the pressure switch. Inspect the pressure switch hose.

The pressure switch must be replaced. The plunger may not be pulling in completely and may only bob around when the pressure builds up inside the furnace. Turn off the power to the furnace by switching off the disconnect switch located near the furnace. When you do this you should hear a clicking noise.

Check for obstructions in the hose. If there is no disconnect. If your pressure switch is stuck it is most likely a problem in the running of the furnace. Which is why i made this video that go.

Pressure switch stuck open replaced pressure switch still getting 3 flashes wich means pressure switch stuck open. Turn off the power. If the switch is open the inducer starts and the resulting pressure change closes the switch. If the inducer comes on the pressure switch is stuck closed.

This is not a repair. If the switch does not close after approx 1 minute the ifc goes into lockout mode. It doesn t take much pressure so don t blow too hard. The pressure switch works with a small plunger that pushes in and out.

The source of pressure switch problems can sometimes be a pain to track down. Furnace pressure switch troubleshooting. Only oem pressure switches should be used. Spray silicon lubricant on the plunger and work it back and forth to loosen the part.