August 2020 - Mitchell Cooling + Heating

If you whistle while you work, you may just enjoy the work you do, but if your air conditioner is whistling, it’s a sign that something is wrong. At the least, your air conditioner is probably working too hard, possibly running up your power bills and shortening the life of your unit. It’s possible that something more serious is going on. So if your air conditioner is whistling, it’s signaling for attention and help. Please don’t ignore its call.

Most Common Reason: Low Return Airflow

In most cases, a high-pitched whistling sound means that your air conditioner isn’t getting enough airflow through the return vents and ductwork: the ones that pull air from your home to the air conditioning evaporator coils to cool it. Your air conditioner has to work harder to pull enough air through the system. This leads to high-pressure, high-speed air moving through the return ductwork, and that causes the whistling you’re hearing.

The same thing can happen when you have insufficient airflow through the supply vents and ductwork: the ones that push cooled air out to your home. This is a little less likely to cause a high-pitched whistling noise and more likely to cause a deeper hum or roar.

Several issues can lead to poor airflow, and some of them you can diagnose and fix yourself.

Is it time to replace your air filter?

A dirty air filter can slow the flow of air through your central air system. If it has been more than three months since you last replaced it or if it looks visibly dirty, go ahead and replace it and see if that helps.

Are your vents blocked by furniture or other obstructions?

Keeping the areas immediately around your vents cleared allows air to flow with less effort. If furniture, drapes, boxes, or other objects are in the way, move them out or over to let the air flow freely through the vent.

Are vent dampers closed?

Some vents have dampers to reduce the flow of air into unused rooms. You may even have closed them accidentally while doing other housework. Air conditioning systems are generally designed to work best with all the dampers open. Closing one in an unused guest room might not have a big impact, but if you have several dampers closed, open them up and see if the whistling goes away.

Are all the doors closed?

If you have a home with many separate rooms and doors, consider leaving at least some of the doors open for easier whole-house airflow. Even though your interior doors aren’t airtight, forcing all the airflow through small gaps around doors can put added strain on your air conditioner.

Was the ductwork correctly configured?

There’s quite a bit of science and engineering that goes into planning a central air system, including the necessary ductwork. Installation technicians have to carefully balance return and supply airflow with the overall capacity of the blower. If your system either wasn’t designed correctly or has been altered over time as new equipment is installed, your system may not have the right balance. This isn’t something you’ll be able to diagnose or fix yourself, but our service technicians will be happy to investigate it for you if the whistling continues.

But It Could Be: Duct Leaks

Your home’s ductwork has many joints along it, where sections of duct come together. When installed correctly, these joints should be well sealed by the installer. This allows the system work efficiently and helps prevent those whistles. Over time, the seals around duct joints can develop leaks, allowing air to flow through.

You probably won’t be able to diagnose or fix this yourself, but you can schedule a service call to get your ductwork joints checked out.

Or Is It: Bearings and Belts

Are you sure it’s a whistle and not a screech? (Sorry to get so technical, but we’re experts in strange house noises.) A squealing, screeching sound could be the drive belt on your blower (for older models) or bearings in your condenser fan motor. You can do an initial diagnosis by standing near the outdoor condenser unit and then by the indoor blower. Does it seem like the sound is coming from one of these units? If so, your blower or condenser may be at risk of failure soon. Reach out to us promptly to get it checked out before something breaks down.

Quiet Comfort

A properly installed and maintained air conditioner should be felt and not heard. If yours is making noises — whether whistles, screeches, rattles, or hums — give us a call. We’ll figure out what your system is complaining about, then do what it takes to return it to quiet contentment.

With so many of us spending more time at home, it’s more important than ever to keep your home safe and comfortable for you and your family. I want to personally reassure you that we’re taking every precaution to protect you, our service technicians, our entire team, and our community while keeping your home cool in the summer, warm in the winter, and comfortable all year round.

The people who work with me at Mitchell Cooling and Heating tend to stick around. Many have been with me 20 years or more. We really are like family. Our customers tend to stick around too. If you’re already one of our longtime customers, then you understand why.

I’ve always believed that the best way to build a business isn’t through high-pressure sales tactics and cutting corners on work. (You might have noticed we don’t even have salespeople.) It’s better, I think, to give honest advice, stay true to your word, do quality work, and take good care of people when it’s easy and when it’s not. It’s maybe not the fastest way to grow, but, in the long run, I think it’s the best.

So things are a little harder right now, but we’ve made it through hard times together before. What’s most important to me is that we’re all still healthy and together when the crisis has passed.

On service calls, all our technicians are wearing masks, gloves, and foot covers. They’re washing their hands frequently and using lots of hand sanitizer. At your home, they’ll stay outside if the work allows and keep their distance if they must come in. We’re also no longer asking for signatures on service tickets.

Whether you’ve relied on Mitchell Cooling and Heating for many years or are considering us for the very first time, I want you to know that we’re doing everything we can to keep your family safe and comfortable. If your air conditioner needs repair, if your furnace needs servicing, or if you’re looking to install a whole house air purifier for added peace of mind, you can call us with confidence. As always, we’ll do what we say we’ll do when we say we’ll do it, always with your family’s health and happiness top of mind.

I thank you for your business. Stay healthy and well, everyone. You mean a lot to us.

Chris Mitchell, Founder

Ask the Expert: Why Is My Air Conditioner Making a High-Pitched Whistling Noise?