Furnace High Pressure Switch Stuck Open

The source of pressure switch problems can sometimes be a pain to track down.

Furnace high pressure switch stuck open.

Replaced circuit board white rodgers 50a50 241 inducer motor comes on then get 3 fl read more. 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. If there is no disconnect. This might free the switch from sticking.

If the switch does not close after approx 1 minute the ifc goes into lockout mode. Using a cloth and a wire brush remove any blockages and dirt from the secondary exchanger and the inducer. The pressure switch works with a small plunger that pushes in and out. Turn off the power.

Tapping lightly on the pressure switch body may open the switch and the unit may start. Which is why i made this video that go. It doesn t take much pressure so don t blow too hard. When you do this you should hear a clicking noise.

Check for obstructions in the hose. If the switch is open the inducer starts and the resulting pressure change closes the switch. The plunger may not be pulling in completely and may only bob around when the pressure builds up inside the furnace. 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.

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. Only oem pressure switches should be used. Turn off the power to the furnace by switching off the disconnect switch located near the furnace. This is not a repair.

The pressure switch must be replaced. On a few furnaces i have found the ventor motor seams to be running fine and power is good but fails on pressure switch. Take off the end so you can blow through it to the pressure switch. If your pressure switch is stuck it is most likely a problem in the running of the furnace.

Spray silicon lubricant on the plunger and work it back and forth to loosen the part. If the inducer comes on the pressure switch is stuck closed. If you have 24 volts the pressure switch is open and not proving the ventor motor. Inspect the pressure switch hose.