It’s easy not to think about your heating and cooling system very much. It keeps on running, ensuring that the temperature inside your home or office stays comfortable. However, when you’ve got a problem, everything comes to a screeching halt, right? Not necessarily. You might notice some very minor yet telltale problems are signs that your system needs maintenance, and soon.

Strange, Loud Noises

Squealing, grating or grinding sounds signal that there’s a problem inside your system. These noises might indicate a fault in the motor, a lack of lubrication or that a part has slipped out of place. This guide at Angie’s List gives a list of other kinds of weird noises that you should not hear from your HVAC assemblies, including repeated clicking sounds or screeching. Furthermore, if you hear a “thwapping” noise, that may mean there’s a blower problem. If left unattended, the motor could wear out.

Weird Smells

Foul or strong odors produced by your HVAC assembly are usually symptoms of a bigger issue. The wire insulation inside one of its components may have burned out. Or if there’s a musty smell coming from the air conditioner, this might indicate the presence of mold inside the unit or its ductwork. In either case, you need to call for service right away.

Too Much Dust Inside Your Building

According to Dominion Power, obstructed air filters or leaky ducts may lead to extreme amounts of dust inside your home or office. Swapping out the filters and fixing the ducts will likely solve this problem, but if it continues, you’ll need to call a professional specializing in heating and cooling repairs.

Uneven Temperature Distribution

If some rooms inside your house or business are too hot or cold — and you didn’t deliberately do anything to cause this — chances are it’s an indication of poor air flow. At this point, only an HVAC technician can properly diagnose and correct the issue.

Lack of Cool Air

Either your AC isn’t switching on, or it’s not supplying any cool air even if you operate it at full capacity. You could be experiencing a compressor or thermostat issue, or the Freon levels inside your unit are low. In either case, it’s a fault that requires service by an HVAC professional.

Your HVAC System Is More Than 15 Years Old

Most HVAC systems are able to work efficiently for about 15 to 20 years. After that, you should consider replacing it with a new, more energy-friendly model. Even if you’re not actively experiencing problems with your heating or cooling, you could benefit from swapping out your HVAC assemblies after about 10 years. The United States Department of Energy suggests that you may be able to reduce your energy costs anywhere between 20% and 40% by upgrading to a newer system.

Now May Be the Time to Call for Service

Minor problems with your HVAC system can appear slowly over time, or creep up on you rather quickly. But before you know it, small inconveniences can blow up into major faults until your heating and cooling completely stop working. Watch for telltale signs of impending failure, and make sure you have a reliable, skilled HVAC professional you can call before your system completely fails.