Testing Furnace Pressure Switch

A multimeter is used to test the pressure switch and check the continuity of the switch whether it is closed or it is opened.

Testing furnace pressure switch.

The draft inducer should start. A multimeter will be needed to test the switch for continuity. If you see anything clean it out. How do you test the gas furnace pressure switch.

There should be either two or three wires going into your pressure switch. To do this the pressure switch wires are removed and the furnace turned on. To test the pressure switch use a multi meter and measure the continuity of the switch as it opens and closes. Probe one lead of the pressure with one lead of your meter while touching the other lead of your meter to.

Hook a manometer to the tubing and check the draft from the heat exchanger in inches w c. Check for obstructions in the hose. Ensure the draft is above the required pressure. Set your meter to volts ac turn your furnace on so it is calling for heat.

Basically the switch needs to be tested to see if it is closing when the pressure diaphragm pulls in. Turn off the power. Turn off the power to the furnace by switching off the disconnect switch located near the furnace. The pressure switch has a pressure at which it closes which is typically negative.

The switch wires have to be removed first. With a manometer or magnahelic. The switch is being tested to check if it s closing when the diaphragm is pulled in.