Checking unit grounding

What is going on

Before you trust any electronic control on this Goodman furnace, confirm it has a solid ground. The gas piping must never be used as the electrical ground, so the path has to run through the furnace ground screw and the supply wiring back to the panel. Do this check with the power off, and call a licensed electrician if the ground path is in doubt.

Likely causes

• A missing or broken ground wire between the junction box and the panel
• A loose or corroded ground screw connection
• A poor connection from the neutral side to the burners, which raises the resistance reading

Check in this order

1. Shut off the electrical power at the disconnect and confirm it is dead with a meter before touching anything.
2. Measure resistance between the neutral (white) connection and one of the burners.
3. Confirm the reading is 10 ohms or less.
4. Trace the ground wire from the furnace ground screw in the junction box back to the electrical panel and confirm it is continuous.
5. Tighten or clean any loose or corroded ground connection and recheck the reading.
6. If the ground path cannot be proven, have a licensed electrician correct the wiring before returning the furnace to service.

More furnace guides

• Airflow lower than demanded, furnace runs on low stage when high stage is expected
• Alternate combustion air opening (upflow or horizontal)
• Alternate vent/flue location (upflow or horizontal left)
• Annual inspection checklist
• Auxiliary limit control (location and purpose)
• Auxiliary limit switch open (blower compartment)