Learn How to Identify and Troubleshoot Common HVAC System Issues
Your HVAC system includes your home’s heating, ventilation, and air conditioning. When it goes out, your home’s comfort goes out with it.
Don’t panic. There are numerous things you can try before contacting an HVAC technician for emergency service. By learning the main signs that indicate your HVAC is not working, you’ll know what to look for — and for some issues — how to resolve the problem yourself.
After covering the symptoms of a struggling or broken HVAC, we’ll walk you through what you can check to see if you can quickly resolve your problem.
Signs Your HVAC Isn’t Working
Critical HVAC issues aren’t hard to spot. If you don’t see, hear, or smell the problem first, you’ll definitely feel it when your home’s temperature becomes uncomfortable. Your HVAC may require repair if you notice:
- Your system doesn’t run at all.
- Your energy bills have increased, despite no change in use.
- Unusual odors, such as burning or sour smells.
- Unusual noises, such as banging, rattling, or screeching.
- Frequent cycling, where the system repeatedly turns on and off.
- Weak or no airflow from vents.
- A frozen condensate line.
- Water or refrigerant leaks.
- Inaccurate thermostat readings or no display at all.
- The temperature in your home doesn’t align with the thermostat.
If you notice one or more of these signs, your HVAC system may need professional attention. Early action can help prevent more serious issues and minimize the disruption in your home’s comfort.
Basic Steps to Take When Your HVAC Is Not Working
If you’ve noticed signs of HVAC trouble, or if your system has completely stopped running, perform this series of basic checks before calling for help. Some of these steps can help you rule out minor issues that you can resolve on your own.
Check the Thermostat Settings
Start with the thermostat. First, make sure it’s in the correct mode, either heating or cooling. If the screen is blank or unresponsive, try changing the batteries. Sometimes an incorrect or malfunctioning thermostat can make it seem like your HVAC is broken when it’s really just a control issue.
Check the Air Filters
Dirty or clogged air filters restrict airflow, forcing your system to work harder. In severe cases, filters can even cause a system shut down. Locate your air filters and check their condition. If they’re caked with grime, a simple filter change may do the trick.
Confirm the Vents Are Clear
Make sure that all supply and return vents are open and not blocked by furniture, rugs, or curtains. Blocked vents prevent proper air circulation and may cause your system to overheat or shut down.
Check the Circuit Breaker or Fuse Box
Go to your home’s electrical panel and look for any tripped breakers or blown fuses related to your HVAC system. If you find a tripped breaker, reset it and see if your system powers back on. If it trips again, that’s a sign of a deeper issue that requires professional attention.
Check the Blower Motor
If your furnace is on but no air is coming out of the vents, the blower motor could be the culprit. Listen for humming or rattling sounds near the furnace. Although you may not be able to fix the motor yourself, recognizing the issue can help your HVAC technician diagnose the problem faster.
Air Conditioner-Specific Checks
Check for a Frozen Evaporator Coil
If your AC is running but not cooling, check the unit for signs of ice buildup. A frozen evaporator coil or condensate line can prevent the system from properly cooling. Turn off the system and let it thaw for several hours. If the problem reoccurs, the issue may be low refrigerant — usually caused by a leak — or a fan motor problem, both of which require the expertise of an HVAC technician.
Check the Condenser Coil for Dirt and Debris
Your outdoor condenser coil should be free of leaves, dirt, and debris. Restricted airflow can cause the system to overheat and stop working. If the unit is dirty, turn it off and carefully clean around the coil using a wet-dry vacuum or soft brush. You can also rinse away debris using a garden hose.
Check the Fan
Inspect your air conditioner’s fan. If it’s not spinning, that’s a key sign the system isn’t working. A stuck or broken fan motor may need replacement, which is best handled by a professional HVAC technician.
Furnace-Specific Checks
Check the Condensate Pan and Drain
High-efficiency furnaces produce condensation during operation. If the drain line becomes clogged or the pan overflows, the system may shut off as a safety measure. Look for signs of water buildup near the unit, and check the pan for clogs.
Check the Power Switch
Most furnaces have a power switch located on or near the unit. It often looks like a regular light switch and can easily get turned off by accident. Make sure it’s in the on position.
When to Call an HVAC Technician
If you’ve worked through the self-check list, and your system still isn’t functioning, it’s time to call an HVAC technician. Delaying service can make the problem worse and drastically affect your home’s comfort, so we recommend
