How to Use Your Senses to Diagnose HVAC Problems

Unless you’re an HVAC professional or an engineer, the idea of confronting problems with your heating and cooling may sound daunting. You may have received advice in the past that says that unless you have these advanced qualifications, you can’t possibly know how to identify problems with your HVAC system. And that if you want to try, you’ll first need to wade through pages of dense technical books and web content to find the answers you’re looking for.

We don’t believe these assertions are always true, because there will always be the occasional problem that crops up that only a true professional can diagnose, many everyday hiccups in your system do not require this level of prior knowledge. With nothing more than the information we’ll share here and your five senses, you can easily diagnose and fix many HVAC problems, all without needing a background in the subject.

Today, we want to walk you through some of the problems you may encounter in your heating and cooling systems. Some of them you can fix yourself while others require a more professional touch, but all of them are issues you can diagnose on your own.

The Air Conditioning System

Encountering a few problems with your air conditioning system? Is it not doing its job correctly, or is it producing unusual noises or smells in the process? Here are just a few of the most common issues you might encounter.

Why Is My Air Conditioner Making Noise?

It doesn’t take a heating and cooling professional to realize that banging and clanging from your air conditioner is a sign that something isn’t working quite right. The sound can be disturbing not only because it causes you to worry about what might be wrong, but also because it’s loud and irritating. If you’re experiencing these noises, don’t worry. The culprit is often easier to detect than you might think. Any of these problems may be causing noises in your air conditioner.

1. There’s a Problem With the Compressor

Is the sound coming from your AC unit a banging noise? If so, this indicates a problem with the compressor. This component circulates the refrigerant in an air conditioner, and the refrigerant is the liquid that cools the air in your home. Over its lifespan, the compressor will experience natural wear and tear that may cause parts to loosen. If these loose parts are inside the compressor, they may be banging around in there, creating the noise you’re hearing.

In most cases, unless you want to continue hearing the noise, you’ll need to replace the compressor entirely. This is because most compressors are sealed shut, and repairs can’t be made without irreparably damaging the shell.

2. The Electrical System Is Struggling

Would you describe the sound you hear as a buzzing noise? If so, you can feel confident that you’re dealing with an electrical problem. You’re most likely to hear these buzzing noises either inside your home near the air handler or outside near the outdoor unit. In either case, the most plausible culprit is still an electrical problem. Some common electrical failings that could be causing this noise include:

In any of these cases, your best solution will be to call an electrician, since it’s dangerous to attempt electrical repairs without the proper training.

3. Air Is Escaping Somewhere

Can the sound you hear best be described as a hissing sound? If this is the case, you’re most likely dealing with air that is escaping through a crack or space where it isn’t meant to go. Think of the sound air makes when escaping through a balloon, and you’ll see the connection. Some of the most common causes of hissing noises include:

  • Incorrectly fitted air filters
  • Duct leaks
  • Loose registers or duct joint

Check each of these components to see which one is causing the problem and either repair it or replace it.

4. Your Components Are Wearing Down

Screeching sounds are some of the most unpleasant to listen to, and are easy to identify. If you hear a high-pitched squealing coming from your air conditioner, it’s probably caused by one metal component scraping along another. To diagnose the precise reason for this unpleasant noise, listen carefully to whether the sound is coming from inside or outside.

If the squealing is originating at the outside unit, you may have a faulty compressor or a failing fan motor. If the noise seems to be coming from the inside, the problem is most likely with your blower fan motor. Either the bearings or the fan belt has probably worn out and is causing the screeching you’re hearing. Replace these components, and the noise should stop.

5. If None of the Above Sound Right, It Could Be One of These Miscellaneous Problems

So you hear a noise in your AC unit, but it doesn’t sound like banging, buzzing, hissing or screeching.

Could you describe it as a clicking sound, instead? If so, there could be a few different things going on. To get an idea of what might be happening, pay closer attention to when and where you hear the noise.

If you hear clicking sounds while the AC is switched on, it’s possible that a small object has become lodged in the fan. Every time the fan spins, it hits this object. Because the fan spins so fast, it creates the clicking sounds you hear. If, on the other hand, the clicking only starts up when you try — and fail — to start an unresponsive AC unit, it’s likely a sign of electrical problems that are responsible for the unit’s failure. Try cleaning the fan to remove any debris. If this doesn’t help, we recommend calling an electrician.

Why Does My Air Conditioner Smell Bad?

There are few things more unpleasant than an air conditioner that smells bad. You can probably guess that this smell is an indication of something gone wrong, but it’s harder to tell precisely what the problem is. To diagnose the issue, start by asking yourself what the strange smell reminds you of. Does your air conditioner smell like:

  1. Sweaty feet? This smell likely indicates that the water isn’t draining properly from your system, resulting in a dirty air conditioner. A thorough cleaning will usually fix this problem.
  2. Exhaust fumes? You most likely have a fluid leak somewhere in your system. A quick call to and a visit from a service professional will sort this problem out in no time.
  3. Gun powder? Do you smell something burning? It could be that your unit’s circuit board or fan motor has shorted out and is causing this burning smell.
  4. Skunk spray? This is a potentially dangerous smell. Skunk smell typically indicates a gas leak, which could be hazardous to you and your family. We recommend evacuating your home and calling the HVAC professionals right away.
  5. Rotten eggs? Unfortunately, the most likely culprit is a dead animal. Small animals can sometimes take shelter in an outdoor AC unit, where they may die and start to decompose, causing the smell. A thorough cleaning will take care of this problem.
  6. Mildew? You probably have mold or fungus growing in or around your air conditioner. You’ll need to locate these mold patches and remove them to get rid of the smell.

Why Is My Air Conditioner Hot?

An air conditioner that blows hot air is both counterproductive and very unpleasant on a hot summer day. Here’s what might be causing this problem:

  1. The thermostat is in heat mode: Sometimes, the solution is as simple as an overlooked thermostat. Are you sure you have the air set to cool rather than heat? Make sure this is correct before you move on to other potential solutions.
  2. The air filter is dirty: If the air filter is dirty, it will be unable to blow out cold air. You can quickly fix this problem by swapping out the old air filter for a new, clean one.
  3. The outside unit is blocked: Take a good look at your outside air conditioning unit. Is anything preventing air from flowing freely through it? Are the coils clogged with dirt, rocks or mulch? If so, shut the system off and clean this unit out.
  4. There isn’t enough refrigerant: The refrigerant is the agent that cools the air as it passes through your system. Without this crucial component, it’s impossible to cool the air. To tell if you’re low on refrigerant, check both the inside and outside units. If ice is forming on them, this is could be a sign that the coolant has leaked and needs to be refilled.

The Heating System

Your heating system is critical in the winter, especially if you live in regions that experience tough winters. If you notice any problems, it’s important to get them fixed right away. Here are just a few of the common issues you might experience over the winter, as well as how to diagnose them.

Why Is My Heater Making Noise?

Like air conditioning units, heating systems may occasionally disrupt your day with strange noises. While sometimes these noises may be little more than a fluke that stops after a few minutes, there may be something more serious going on. If the noise persists, listen carefully to what kind of sound it is and diagnose the problem according to this guide. Based on the type of noise you hear, one of these may be the underlying problem.

1. Problems With the Motor, Belt or Bearings

Would you describe the noise as a screeching sound? If your furnace is screeching as it runs, this indicates a possible problem with the motor, a belt or the bearings. None of these are immediate emergencies that present health hazards, but these are still problems that you’ll want to get checked out before too long. Leaving issues like these to fester could result in more expensive repairs later.

2. Loose Components

Rattling noises sounds are another common symptom of problems in your heater. If you hear these sounds, this is usually a sign that some component has come loose and is rattling against another part. Some fixes to this problem may be to add extra screws to any ducts that might be loose, or taping down any pieces that are hanging loosely. Another possibility is that the furnace is rattling against the floor.

Sometimes, even if you hear loud noises coming from your heater, there aren’t any underlying problems. Even if you hear loud clanging noises, you might have nothing to worry about. Clanging or knocking sounds are typical right as the furnace is turning on. As the furnace starts to heat up, different parts are expanding and contracting due to the heat, which can often cause a clanging sound or even something that sounds a bit like knocking. This type of clanging is perfectly normal and doesn’t indicate that there is a problem. This sound should stop as the heater becomes fully warmed, although it may kick on again as the heater cycles.

If you’re concerned that the clanging or knocking you usually hear suddenly sounds different, or you aren’t sure if what you’re hearing is normal, call a professional and get it checked out for peace of mind.

Why Does My Heater Smell?

Noticing a strange burning odor coming from your heater? There are a few possible reasons for this smell. Try to be as specific as you can about what exactly it smells like is burning, and then check our solutions to see if one of these might be behind the smell filling your home.

1. You Haven’t Used Your Heater in a While

The smell of burning dust is hard to identify, as it smells like a very generic “burning” odor. The best way to identify this type of burning is to note when you smell it. Is the smell filling your air just as you turn the heater on for the first time in the fall? Does the smell fade away after a day or two or even just a few hours of running the heating system? Burning dust is likely the culprit.

Over the warm season when you aren’t using your heater, dust collects on all the various components. In the fall, when you turn the heating system on, this dust is slowly burned up as the metal it’s resting on heats up. This is a natural and harmless process. Simply let your heat run, and the smell should soon dissipate.

2. Something Is Melting in the Heater

The smell of burning plastic is hard to mistake. If you smell burning plastic or rubber, the most likely reason for this is that a toy or similar small object has gotten lodged in or around your furnace and is slowly melting. The best way to deal with this problem is to shut off the furnace and try to locate the source of the burning by following your nose. Once you’ve found the melting object, wait until both the heater and the object are cool before removing it. You may also need to remove any burn residue.

3. The Heater Is Having Electrical Problems

Unfortunately, electrical problems usually indicate a need for professional help. If you think the burning smell seems electrical, wait for one or two furnace cycles. The smell may dissipate on its own. If it does not, however, we recommend shutting off the heater and calling for assistance.

The Air Ducts/Ventilation

Something going wrong in your home’s air ducts? Here’s one of the common problems you may experience there.

Why Are My Air Ducts Making Noise?

Air ducts making strange banging and popping noises? It happens to the best of us. There are a few different possible causes of these noises.

1. Your Ducts Are the Wrong Shape

Some ducts are round, and some are rectangular. Both shapes get the job done, but unfortunately, rectangular ducts tend to be noisier due to their shape. If this is the problem, one solution is to replace the ducts altogether or just the noisy ones.

2. Your Ducts Are Too Large or Too Small

The problem also might be that your ducts are simply too large or small for the amount of airflow needed. Metal ducts expand as heat passes through them, causing them to make noise as they press into their surroundings. Other than replacing the ducts entirely, your best solution here is to have an evaluation of your ducts to determine proper sizing.

Contact Zimmerman Plumbing, Heating & Air Conditioning Today

Sometimes, the job is simple, and you can easily complete it yourself with just your wits and a well-stocked toolbox. Other times, there’s something more serious going on that’s best left to the professionals.

If you’re located in the Harrisburg area and you’re experiencing something that’s beyond your capabilities to fix, contact us here at Zimmerman Plumbing, Heating & Air Conditioning. Schedule your free estimate today to get to the bottom of the problems plaguing your HVAC systems.

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