Testing Furnace Pressure Switch

With a manometer or magnahelic.

Testing furnace pressure switch.

Set your meter to volts ac turn your furnace on so it is calling for heat. If there is no disconnect. A multimeter will be needed to test the switch for continuity. There should be either two or three wires going into your pressure switch.

Basically the switch needs to be tested to see if it is closing when the pressure diaphragm pulls in. How do you test the gas furnace pressure switch. Ensure the draft is above the required pressure. To do this the pressure switch wires are removed and the furnace turned on.

The pressure switch has a pressure at which it closes which is typically negative. The draft inducer should start. Check for obstructions in the hose. A multimeter is used to test the pressure switch and check the continuity of the switch whether it is closed or it is opened.

Inspect the pressure switch hose. The steps are as follows. The switch wires have to be removed first. Hook a manometer to the tubing and check the draft from the heat exchanger in inches w c.

If you see anything clean it out. The switch is being tested to check if it s closing when the diaphragm is pulled in. Probe one lead of the pressure with one lead of your meter while touching the other lead of your meter to.