Testing Furnace Pressure Switch

Turn off the power.

Testing furnace pressure switch.

Basically the switch needs to be tested to see if it is closing when the pressure diaphragm pulls in. Probe one lead of the pressure with one lead of your meter while touching the other lead of your meter to. To do this the pressure switch wires are removed and the furnace turned on. Ensure the draft is above the required pressure.

Inspect the pressure switch hose. A multimeter will be needed to test the switch for continuity. The switch wires have to be removed first. The draft inducer should start.

Hook a manometer to the tubing and check the draft from the heat exchanger in inches w c. The switch is being tested to check if it s closing when the diaphragm is pulled in. If there is no disconnect. The steps are as follows.

If you see anything clean it out. How do you test the gas furnace pressure switch. The pressure switch has a pressure at which it closes which is typically negative. Set your meter to volts ac turn your furnace on so it is calling for heat.

There should be either two or three wires going into your pressure switch. Check for obstructions in the hose. With a manometer or magnahelic.