How to Test the Pressure Switch on My Gas Furnace

A faulty pressure switch can cause your furnace to shut down. Broken fan motors and cracked tubes are leading causes of inoperable pressure switches. You’ll need to test your pressure switch for continuity to determine whether it’s the cause of your problems. A multimeter allows you to test for continuity by touching two probes to the pressure switch terminals. The reading on your multimeter will indicate if you need a new pressure switch.

Multimeter

Instructions

- 1
  Remove the front cover from your furnace to reveal the furnace components.
- 2
  Locate the pressure switch. The switch looks similar to a small metal wheel that’s either black or silver in color. Two wires connect to the switch. Disconnect the wires. Never attempt to test a pressure switch while the wires are connected.
- 3
  Turn on your multimeter to the lowest ohms of resistance. Plug the multimeter probes into the multimeter if they are not already connected. Touch and hold the negative probe to one terminal on the pressure switch. Take the positive probe and do the same to the other terminal. Look at your multimeader reading. If it reads “0” or close to “0,” the pressure switch is in working order. If it reads another number, the pressure switch has no continuity.

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