Tips to diagnose a noisy HVAC system

July 1, 2020

As summer settles in, you’ll probably find that you’re using your air conditioning more often. Air conditioning is a real blessing in a hot climate, but if your HVAC system is noisy and not operating at peak efficiency you may also find it a source of irritation, particularly if you’re trying to work from home.

There are many possible reasons why your air conditioning system is slowly driving you a little bit crazy. Let’s examine some of the common problems that generate unwanted noise, and look at how these problems can be addressed.


You can expect your HVAC system to run frequently when the weather gets warm, but if your system is always running, or if it constantly cycles on and off, it could be an indication of serious problems.


  • Cleaning is required. If the coils of your air conditioning system need to be cleaned, or if your air filters are dirty and clogged, your system may run constantly.

  • Leaking refrigerant. Without refrigerant in your system, your AC won’t be able to cool your home. Therefore it will continue to run.

  • Frozen coils. If your system is running constantly but blowing warm air it could be an indication that the coils are frozen.

  • Faulty thermostat. Your thermostat determines when your system starts and stops, keeping the temperature in your home at a consistent level. If it is broken, the system may run constantly.

  • Faulty ductwork. If there are numerous holes in the ductwork in your home, cool air will be lost, and your AC will have to run harder to make up for the loss.

An HVAC system that runs constantly will cause you to use more electricity and will cause increased wear and tear on the parts. Besides, a constantly running air conditioner is often a warning that there is a serious underlying condition that could cause a complete failure. If you’re experiencing any of these issues, get a check-up right away.


You can expect some background noise to be normal when you’re running the AC, but it’s hard to think of anything more annoying than a constant, low-level whistling sound in the background as you try to concentrate on a task.


  • Clogged or dirty filters. If the airflow is blocked by dirty filters, air will have to force its way through small openings, and that can cause whistling.

  • Duct leaks. Small holes or cracks in your ducts can cause whistling as air moves through the ducts.

  • Improper fan speed settings. A fan that runs too fast can overload the ductwork and cause noise as air is forced out.

  • Poorly sealed registers. If your air distribution registers aren’t sealed properly, air escaping around the edges can cause whistling.

Identifying the location of a whistle in the HVAC system can take a bit of detective work, and it might require a few tries to isolate and eliminate the problem. Sometimes the problem is related to airflow from the motor, so it may be necessary to replace the motor or recalibrate the motor’s speed. Our HVAC professionals at Team Enoch have the expertise to track down and fix the problem.


Rattling sounds from your air conditioner can originate from several different locations. In each case, there will be a different solution to the problem. Let’s take a tour of the most common causes of rattling.

Loose registers. Sometimes a rattling sound can come from a loose register. If the screws holding the register into the ceiling, floor, or wall are loose, the movement of air through the register can cause a rattle to occur. Check for loose screws and tighten them up. Also, check the register itself. Sometimes the directional vanes in the register may be damaged and rattle as a result. You can buy new registers at most home improvement stores, and it’s usually an easy task to replace them.

Worn fan bearings or damaged fan blades. If the rattling isn’t confined to one spot, the noise may be coming from the main air handler, the fan blades, or the fan motor. You’ll want to have a pro check this out.

Your outdoor unit isn’t properly leveled. If the outside unit of your air conditioning system isn’t level, that can sometimes cause a rattling sound. It will be easy to identify the source of the sound in that case. Don’t try to level the unit yourself — caution needs to be taken with the input and output lines and the electrical connections.


One of the most annoying sounds an air conditioner can create is a loud squeaking or squealing. In most cases, the cause can be traced back to a lack of proper and preventative maintenance. You can usually narrow squeaking and squealing sounds down to a few causes.

A failing blower belt. If the belt driving the blower has slipped or has gotten too old, it will often let you know by the sounds it makes. In addition to being a real annoyance, an aged or slipping belt will impede the efficiency of your AC unit, causing you to use more energy to keep your home cool.

Poorly lubricated motor shaft bearings. This is a problem that is easily avoided with regular preventative maintenance. Regular servicing of your HVAC system will include the necessary lubrication of crucial moving parts.

Keep It Quiet and Keep It Cool

Many of the problems we’ve described are telltales of bigger problems. It’s a wise policy to consider any unusual noise in your air conditioning system as a potential sign of a bigger problem. And like most problems, the problem associated with a small noise will, if left unchecked, usually become a bigger and more expensive problem. And remember, the last time you want to be tackling a major repair to your air conditioning is during the hot summer months. Stay alert and stay on top of maintenance and you’ll find that you’ll stay cool, stay focused, and probably save money too.

If you need help figuring out what the best way to tackle a noisy air conditioner, remember getting a quote is free! Our qualified and licensed HVAC professionals are here to help!

Leave a Reply

Your email address will not be published. Required fields are marked *


Team Enoch’s roots are right here, in the Dallas - Fort Worth community. We love building lifelong relationships with our customers while providing them high-quality care and outstanding customer service.

Our professional technicians & Tyco Certified Copalum Installers serve DFW and its surrounding areas:
Grand Prairie
Trophy Club
Team Enoch DFW
(817) 888 8880
8940 Creek Run Rd. 
Fort Worth, TX 76120
Team Enoch Austin
(512) 882-8880
1006 Nimbus Dr.
Pflugerville, TX 78660

Get a quick response via text!

Please enable JavaScript in your browser to complete this form.

Enter your information, and our team will text you shortly.

linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram