How to Check Heat Elements in Furnaces

Electric furnaces contain one or more heating elements arranged in rows adjacent to a blower motor for circulating warm air. The elements are typically made of wire coil surrounded by a heat-treated ceramic material to reflect the heat produced by electrical resistance. If the furnace stops working or does not seem to produce as much heat as it once did, try troubleshooting the individual elements with a multimeter to isolate the problem. It may be necessary to replace only one element.

Nut driver
Multimeter

Instructions

- 1
  Shut off the furnace at the circuit breaker to cut the electricity to the appliance. Turning off the unit at the wall thermostat is not sufficient. Wait for the furnace to cool.
- 2
  Remove the bolts in the access plate on the side of the unit using a nut driver. Take off the plate to expose the rows of heating elements.
- 3
  Pull the pair of wires off the end of one element at a time to expose the connector blades on the element. Each wire is attached to a slide-on connector that pulls off under gentle pressure.
- 4
  Adjust the multimeter to test for continuity, measured in ohms. This lets you determine if an element is defective.
- 5
  Hold each test rod on the multimeter against one of the connector blades on the element. Check the meter display. A normal reading for an electric furnace element falls in the range of 70 to 90 ohms, depending on the power capability of that particular unit. A zero or infinite reading means the part is bad.

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