What to do When Your Heater Makes High-Pitched Noises

Few things strike fear in the heart of a homeowner more than hearing one of your home’s major mechanical systems suddenly start to make unexpected and loud sounds. While booms, bangs, and metal against metal noises can often spell big trouble, the sound of a high-pitched screech or squeal coming from your furnace doesn’t always signal disaster. However, you do need to check out what’s causing it.

The causes of high-pitched noises – and how to address them

Understanding what’s causing the sounds and why is the first step toward getting the problem solved, either by troubleshooting it yourself or calling a professional. Here is a list of possible culprits and recommended remedies.

Blower problems

The blower on your furnace does exactly what its name suggests. It is responsible for forcing or blowing hot air through the airducts and heating the various rooms in your home. Certain blower problems can produce high-pitched noises because of damaged parts like fan belts or motor bearings, lack of maintenance, or other issues.

Old, damaged or loose fan belts

If your furnace is older and has a belt-driven motor, the reason your heater is making a high pitched noise may be related to the fan belts on the system’s blower. In addition to making high-pitched squealing sounds, belt issues can also be accompanied by the smell of burning rubber. Take a look at the fan belts. If they’re just loose, you may be able to tighten or adjust them. If they are damaged or have deteriorated, you can replace them. If you’re not handy or run into problems, call an HVAC professional.

Worn out motor bearings

If you have a newer furnace, it may be direct-driven instead of belt-driven. In this case, your heater’s high-pitched noise is likely being caused by problems with the blower motor bearings. Since these parts bear the brunt of most of the force and friction as the motor rotates, they wear out and have to be replaced. Replacing blower motor bearings requires specialized tools and training, so you’ll want to call an HVAC expert.

Loose, broken or misaligned motor wheel

If motor wheel problems are to blame for your furnace noises, it’s because the spinning motor wheel is rubbing against the surrounding metal surface. Adjusting or repairing the blower motor wheel is a job that an HVAC professional should handle. Contact an expert to ensure the repair is completed correctly.

Lack of lubrication

Over time, the oil that lubricates the shaft and motor bearings, as well as other moving parts in your furnace, dries out. Once that happens, they begin to scrape against each other, which can cause your heater to make high-pitched noises. If you have an older furnace that has two shaft bearings and two motor bearings, you should be lubricating them once a year. To do so, clean and remove the oil caps and apply just a couple of drops of lightweight machine oil, and then replace the caps. If you don’t feel handy enough to handle the job, call in an HVAC professional.

Motor malfunction

A heater making a high-pitched noise may have a motor that isn’t working properly. The problem may be caused by worn out bearings, overheatine to a buildup of dirt, or a problem with the capacitator.

First, check to see whether the problem really is with the motor by turning off your furnace and switching your thermostat to the “fan only” setting. If you see or hear the fan come on after a couple of minutes, the motor isn’t the problem. If it doesn’t come on, you may have a tripped circuit breaker, so make sure to check the breaker box for any irregularities. If the circuit breaker looks fine, the motor is bad and likely needs to be repaired or replaced. Time to call in a HVAC professional.

 Airflow problems

If the noise your furnace is making is less of a screech or squeal, but rather sounds like high-pitched whistling, it probably means the blower is having problems drawing in enough air to be heated. This can be caused by:

Dirty or damaged air ducts

If your ducts are dirty or damaged, you’re hearing whistling sounds because the air flow is escaping from holes or being forced through a restricted space. Over time, various items from screws and sawdust to baby toys and dust rags can fall into supply side vents and grates and block the ductwork. To see whether this is your problem, take off the vent cover and look inside. You might be surprised at what you find and how quickly cleaning it up solves your problem. If the ductwork itself is damaged, contact an HVAC professional to have it replaced.

A dirty air-filter

Failing to change furnace air filters can cause the equipment to struggle to pull in air. This can create a whistling or squealing noise while your heater is running. This is a cheap-and-easy DIY fix. You can avoid high pitched whistling noises caused by dirty furnace filters by changing them at least once every 90 days.

Closed or blocked air vents and dampers

Whining sounds are a sign that the heating system is straining to get enough air to function properly. Make sure the supply vents are set to the open position in all rooms in your house. Also make sure large furniture like bookcases, dressers, and couches aren’t blocking them. The same goes for dampers, which are the metal valves that you can open and close to regulate where air is delivered to various parts of your home.

Undersized return grilles

Grilles that are too small for the job make it hard for the system to take back in enough air, which causes the heater to make a high pitched noise. Consult with an HVAC professional to match the size of your return grilles to the requirements of your heating and cooling system.

Closed doors

Most supply vents that deliver warm air are located in rooms with doors, while return grilles that take air back to the furnace are often located in halls and stairways. Closing the doors to rooms in your home forces the return grilles to work harder in or suck the air under and around the door, which can aggravate airflow problems and cause high pitched heater noise. Keep your interior doors open in order to keep the air circulating freely.

Contact Chas to solve your HVAC problems

Whether you have a concern about your heater making high pitched noises or know you need a repair or replacement right away, call Chas Roberts. We have been keeping Arizona families safe, happy, and secure in their homes by providing quality service for more than 75 years. Contact us today for all your HVAC needs.