Furnace High Pressure Switch Stuck Open

Using a cloth and a wire brush remove any blockages and dirt from the secondary exchanger and the inducer.

Furnace high pressure switch stuck open.

The source of pressure switch problems can sometimes be a pain to track down. Take off the end so you can blow through it to the pressure switch. The pressure switch must be replaced. Turn off the power.

Or you test any voltage between 1 to 23 volts then you have bad contacts and the full power is not getting through causing the furnace to fail. The pressure switch works with a small plunger that pushes in and out. Check for obstructions in the hose. Inspect the pressure switch hose.

Which is why i made this video that go. This is not a repair. Tapping lightly on the pressure switch body may open the switch and the unit may start. If there is no disconnect.

Pressure switch stuck open replaced pressure switch still getting 3 flashes wich means pressure switch stuck open. It doesn t take much pressure so don t blow too hard. After all this the furnace should fire right back up. This might free the switch from sticking.

So go ahead and put the hose back on put the access panel back on the furnace turn up the thermostat to its highest setting. 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.

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. Turn off the power to the furnace by switching off the disconnect switch located near the furnace. If you have 24 volts the pressure switch is open and not proving the ventor motor. On a few furnaces i have found the ventor motor seams to be running fine and power is good but fails on pressure switch.

If the inducer comes on the pressure switch is stuck closed. If the switch does not close after approx 1 minute the ifc goes into lockout mode. The plunger may not be pulling in completely and may only bob around when the pressure builds up inside the furnace. If your pressure switch is stuck it is most likely a problem in the running of the furnace.