Is your HVAC system calling out to you?

Is your HVAC system calling out to you? Could this be a wake-up call? Pretty much all home systems make some noises at certain times the dishwasher spraying water on dishes, your refrigerator running, and so on. We get used to these. However, we can usually tell when a noise sounds unfamiliar. Since our HVAC system can make many different sounds, and since many of us take their continual operation for granted (we shouldn’t, though), it would be a good idea for us owners and renters alike to know more about this topic. In this article, we’ll begin by describing some of the common noises you might hear coming from your HVAC (meaning heating, ventilation, and air-conditioning) system. Then, we’ll explain what might be happening and what you should do next.

First, though, we’ll go over the key components of an HVAC system so that you have a kind of “roadmap” to follow here.

The HVAC System

An HVAC system keeps the climate comfortable in your house, apartment, or workplace. It is comprised primarily of the heating and (often) cooling sources, as well as the ductwork that circulates the warm or cold air and a control unit.

Heating Sources

  • Furnace: There are gas (the most common), oil, and electric furnaces. All have similar parts, including a burner (gas or oil) or heating element (electric) a blower, a heat exchanger, a filter, a plenum, and various other parts.
  • Boiler: Like a furnace, a boiler heats your house. However, it does so by distributing heated water through tubes installed in your house.
  • Heat Pump: “For climates with moderate heating and cooling needs, heat pumps offer an energy-saving alternative to furnaces and air conditioners (by using) electricity to move heat from a cool space to a warm space.”

Cooling Sources

Heat pumps can also meet cooling needs in moderate climates. However, the most common cooling source is air conditioning (AC) which comprises both outdoor and indoor AC units.

AC works by using chemical refrigerants (hydrochlorofluorocarbons or HCFCs) that convert from gas to liquid and back again quickly. Here too, there is a heat transfer process involved.

An air conditioning system consists of an evaporator, a compressor, a condenser, and an expansion device. The part inside the home where the refrigerant evaporates is the evaporator. Indoor fans blow air across the evaporator’s coils.


For a heating and/or cooling system, the ductwork is simply a “transit” mechanism to disperse the heated or cooled air throughout the house.


A thermostat controls a home’s interior climate by regulating the temperature. Some thermostats are programmable and can be quite sophisticated in what messages they can send to the HVAC system.


Common Noises Made by the HVAC System—And How to Address Them

Would you believe that there is a solution to each of the common HVAC noises you might be hearing at home? There most certainly is. However, be forewarned that the solution might involve some amount of complexity and cost.

Still, if you have any doubts or worries about what’s going on, it’s much better to call a Green Apple HVAC technician now than wait until the problem gets worse.

Squealing or Screeching

This can signal a bad fan belt in the blower. If it is, that belt should be replaced. The sound also might mean that the motor needs lubricant—which you may or may not be able to do yourself depending on the furnace make and model.

It does take a special type of lubricant, though (not an ordinary household type). When in doubt, call a Green Apple HVAC technician.

Rattling (Inside the House), Clanking or Banging

Like “thwapping,” these sounds could be related to the furnace’s blower assembly or motor, and are likely due to something being either loose or broken.

If you hear louder banging sounds when the blower is running, shut the system off until you can get help. At this point, something has broken or gotten disconnected.


If the sound is located near your ductwork and the heat hasn’t been on for a while, this is a common noise. It’s the sound of cold metal ducts expanding due to the rush of warm air.

If the popping comes from another source or doesn’t go away, then it might be time to call a Green Apple technician to find out for sure what’s going on.


Is this common HVAC noise coming from your AC unit? If so, it could be some sort of compressor malfunction. It also might be a refrigerant leak that causes the unit to freeze. Or it might be just a loose part vibrating. You should have it checked out though.

Frequent Clicking

If the clicking is coming from the AC unit, most of the time it’s either the outside compressor or the inside air handler. There are several possible causes, which can easily be diagnosed by a Green Apple technician.

Is the clicking coming from the furnace? If the weather is getting colder and you turn the heat on for the first time in a while, clicking should be a welcome sound. It tells you your system is working.

However, if the clicking continues and is coming directly from your furnace, that could be a sign of an ignition system (pilot light or electronic ignition) malfunction.

Green Apple Plumbing & Mechanical NJ are the experts you can trust. We have been serving the New Jersey area for years with professionalism and expertise. Customer service and care are always our number one priorities. If you have any questions or concerns regarding any of your plumbing or HVAC needs call toll-free today at 888-611-7191

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