HVAC Troubleshooting Guide

If your home comfort system isn't operating the way it used to, there are a few things you can check before calling for service.

Keep Your Home Comfort System Running at Peak Performance

Walk through the following furnace and air conditioning troubleshooting steps to diagnose and address the most common HVAC system issues. If you still believe your HVAC system is not working properly, please call your YORK® Contractor with your system or unit model number for service.  

Air Conditioning Troubleshooting Guide

Is your thermostat ready?

  • Is your thermostat set in the cool position (or warm for winter heat pump operation)?
    • If so, is your outdoor air conditioning or heat pump running?

Is everything on?

  • Did the circuit breakers trip to the OFF position?
  • Is the outdoor disconnect switch on your outdoor unit in the ON position?
    • The disconnect switch is usually a small metal grey box mounted on a wall near the outdoor unit.
  • Is the blower motor in your furnace or air handler running when your thermostat is activated?
    • Make sure the furnace switch is in the ON position.

Is there proper airflow?

  • Have you changed your filter?
    • A blocked filter can cause your unit to shut down due to lack of proper airflow.
  • Are the air registers (supply or return ducts) plugged?

Gas Furnace Troubleshooting Guide

Is your thermostat ready?

  • Is your thermostat set in the HEAT position?
  • Is the temperature setting on the thermostat set higher than the thermostat's indoor temperature?

Is everything on?

  • Is the power turned on for your furnace?
    • At the thermostat, turn the fan to ON. The fan should run when power is being supplied to the furnace.
  • Did the circuit breakers in the circuit breaker box (or electrical panel) trip to the OFF position?
    • Check the SSU light switch on the gray box located at the furnace to make sure it is in the ON position.

Is there proper airflow?

  • Have you changed your filter?
    • A blocked filter can cause your unit to shut down due to lack of proper airflow.
  • Are the air registers (supply or return ducts) plugged?
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Speak with an Expert

Our Certified Comfort Experts are highly trained in home heating and cooling needs, and can provide you with a personalized solution that's right for your home.

Schedule a Home Consultation

Learn More

YORK® | Parts

Repair or Replace: Replacing Existing Equipment

Find out how to get replacement parts for YORK® residential equipment here. 

YORK® | Maintenance Tips

Maintenance Tips

Helpful tips for inspecting your own home comfort system – including indoor air quality (IAQ) equipment, air handlers, air conditioner/heat pumps and furnaces. 

YORK® | Preservice Checklist

Preservice Checklist

You can help your YORK® Certified Comfort Expert™ Contractor make maintenance visits fast and productive. Here you'll find tips on what to check and prepare before your contractor visits.