7 Common HVAC Problems That Require an Expert

HVAC systems can face problems, and many of them require an expert. This guide explains 7 common HVAC problems that require an expert.

Is your HVAC giving you trouble lately? Are there weird sounds coming from the unit or strange smells from the vents?

More importantly, what should you do about these problems? Should you try and fix them yourself or is it time to call an expert?

It’s true that some common HVAC problems can be fixed and prevented by proper DIY maintenance. Others, however, require expert knowledge to solve. Furthermore, attempting a fix that is beyond your knowledge and skills is dangerous.

So, how can you tell if your HVAC issues warrant professional help? You’ll find the answer below.

Specifically, the following guide lists several common issues that can only be fixed via professional HVAC repair. Call your local HVAC repair technician if you find your problem on the list below.

1. DIY HVAC Fixes Don’t Work

Before we even start listing common HVAC problems, there are some DIY steps you can take that solve a lot of common issues. You want to make sure you do these steps first. That way, if these methods don’t fix the problem, you’ll know for sure that you need expert help.

The 2 most common causes of HVAC problems are a clogged air filter and an improperly set thermostat. Check both of these now.

If your air filter is dirty, replace it. Otherwise, it obstructs the airflow, eventually damaging your whole system.

Next, check your thermostat settings, especially whether or not it’s running a program. Often, it seems like your thermostat is behaving randomly when it’s actually following a pre-programmed schedule. Regardless, make sure the thermostat is set to perform the way you want it to.

Lastly, if you’re using an oil furnace, make sure you have enough fuel. Take care of these maintenance steps now and your problems might go away on their own.

2. Moisture Leaking From the System

On the other hand, if you have moisture leaking from/pooling around your HVAC unit, shut it down. Then, call for emergency HVAC repair.

This could be a sign that your HVAC is leaking refrigerant, which is poisonous and potentially even fatal. Only professional HVAC technicians are qualified to address this problem safely.


3. Weird Noises

There are so many strange noises your HVAC might make, it would take a whole other article to explain them all. But here’s an overview of HVAC noise phenomena that you should never ignore.

Your HVAC Is Very Loud/Keeps Getting Louder

Your HVAC is never supposed to be loud, period. If it is noticeably loud, there’s a problem.

Often, it means that your system needs lubrication or that a component or the system itself is wearing out. Whatever the cause, though, it’s best to have a professional come and take a look at it.

A Loud Bang or Pop

A single loud bang every once in a while is probably your ducts reacting to the change in temperature when your system starts or stops. A professional might be able to insulate your ducts better so this stops happening. Or, they can replace the ducts.

Slow Then Fast Clanking or Flapping

A slow-to-fast tapping noise that sounds like a drum roll is most likely coming from your fan. That is, the blades are probably contacting some debris or some component, like the fan housing. it’s dangerous to mess around in there without proper training so call it in.


A grinding noise probably means that two metal parts are grinding against each other. This is very dangerous because it can create sparks that may start a fire. If you hear anything like this, shut off your HVAC and have it repaired immediately.


A loud screech or squeal, especially upon startup, is usually a problem with the blower motor or a fan belt. Lubricating it could help. but you may need to replace one or more components.


Rattling generally indicates a loose part that needs securing. You can try tightening some of the more accessible, exterior parts. But leave the interior parts to the professionals.

Also, this sound could mean that your HVAC is simply dying. So it’s best to call a professional to check out this noise, anyway.

Rumbling Furnace

If your furnace is rumbling, it might be having trouble lighting. You can try the pilot flame reset button if you have one. Otherwise, you’ll probably need a professional to clean or replace the igniter.

4. Weird Smells

Put simply, any smell coming from your vents is a bad sign. For instance, a burning smell could indicate burnt-out electrical wiring. This is a fire hazard and must be addressed right away.

Other HVAC odors are caused by mold infestations or even a dead animal in the ducts. Regardless, the only way to diagnose/solve these issues is to call an expert.

5. The System Keeps Shutting Off or Tripping the Circuit Breaker

Your circuit breaker, and your HVAC itself, will automatically shut off to prevent certain issues, like safety hazards and breakdowns. For example, a sudden power surge can overload the system and fry the electrical components. In this case, the auto-shutoff feature cuts the power before any system damage occurs.

Similarly, an electrical issue associated with the HVAC can be a fire hazard. And malfunctioning components could burn out your motor. These issues are also prevented by the auto-shutoff.

In other words, if your HVAC keeps tripping this safety feature, call an expert to find out why and to put a stop to it.

6. The Pilot Light is Out/Won’t Relight

As mentioned above, your furnace can sometimes have trouble lighting due to a faulty or dirty component. If simple, DIY methods don’t get the pilot relit, call it in.

7. The HVAC Is Constantly Running

Unless your fan is set to “on,” the HVAC should shut off once the desired temperature is reached. But if it just runs all the time, even when it’s set to “auto,” it means it’s having trouble reaching the temperature it’s set to. This usually indicates that a component or the system itself is worn out and needs replacing.

8. The AC Blows Warm Air

Warm air from your AC could mean that your compressor’s failing. Or, you might be low on refrigerant. Either of these issues is a job for the professionals.

9. Unusually High Heating/Cooling Bills

When you’re system’s running inefficiently or a component is failing, your HVAC works extra hard to make up for it. This causes your heating and cooling bills to skyrocket. Or, if you have an oil furnace, it begins burning up fuel very fast.

There are so many things that can cause this issue. So, it’s best to call for professional inspection/repairs if you notice it.

Call an Expert If You’re Experiencing These Common HVAC Problems

These common HVAC problems are not to be taken lightly. If you noticed any of these issues at your home or business, contact us now for professional HVAC repair.