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HVAC Repair 101: 6 HVAC System Sounds You Never Want to Hear

Your HVAC system will make noises when it is heating or cooling your home. With the weather starting to warm up here in San Antonia and Austin, we are at the time of year when we switch from AC to heat and vice versa. Now is a great time to do a self-inspection of your HVAC system to determine if it is making strange sounds that could require HVAC repair.

1. Loud Squealing Sound

This sound is like the one you might hear when turning on the AC in your car for the first time. It could mean one of several different things:

  • You have a loose fan belt that is slipping and needs to be tightened.
  • The fan belt is getting ready to break.
  • For systems without fan belts, this sound often indicates various moving parts and components need to be lubricated.

Young man fixing air conditioner at home

2. Banging or Scraping Sound

If you hear metal-on-metal banging or scraping, this is never good. Shut the HVAC system off right away to avoid further damage. Something has come loose and is allowing moving parts to bang or scrape against each other.

Ignoring the problem will only cause it to get worse. When whatever came loose falls off, it could damage the fan or other moving parts, resulting in a costlier repair.

3. Loud Clunking or Banging Sound at System Start-Up

If your HVAC system is making a loud clunking or banging sound when it starts up, something is wrong. With gas furnaces, this could indicate a buildup on the burner unit. When the heat turns on, essentially, you are creating a mini-explosion inside the furnace.

With air conditioners, this sound can occur if parts need to be lubricated, as the system is having to work harder to get everything moving. The system may continue to bang or clank or, if there is some lubrication left, it may stop while the system runs.

4. Shaking and Rattling Sounds

These sounds mean something is not right inside the system. There is excess vibration occurring that is causing the system to shake and rattle. A bolt or fan blade could have come loose.

You could also have other types of parts inside that are loose and causing the excessive vibrations. You definitely want to call a heating and air conditioner contractor for repair service ASAP.

HVAC technician working on controls of air conditioner

5. Clicking Sounds at the Thermostat

Clicking is normal when the thermostat sends a signal to turn the system on and again when it sends the signal to shut the system off. However, if you notice that the clicking sounds have changed or continue while the system is running, something is wrong. Typically, it is some type of electrical problem like a wire having come loose or your thermostat getting ready to fail.

6. Buzzing Sounds

If your HVAC system is buzzing but not turning on, shut it off right away and schedule HVAC repair. Buzzing indicates a few different types of problems that could include:

  • Bad Ignitor Switch
  • Bad Ignitor
  • Bad Blower Motor
  • Bad Blower Fan
  • Loose Electrical Wires

If you notice any of these sounds or others that do not seem normal, please feel free to contact Christianson Air Conditioning & Plumbing at 512-246-5400 to schedule HVAC repair service. We service the San Antonio, Austin Metro, Temple, and New Braunfels areas.

Now is also a great time of year to schedule HVAC system tune-up maintenance service to make sure your system is all ready for the hot Texas summers!

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