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When we think of summer, the first things that come to mind are frozen treats, the beach, and time with the family. But, summer isn’t all perfect. Heat and humidity become major hassles as spring ends and summer descends. Even more, if you live in a warmer climate — you might be dealing with heat and humidity for most of the year.

While most of us love the occasional sauna experience, a properly functioning air conditioner is essential to comfortable and healthy living. In this guide, we’ll cover how to maintain a HVAC system so that your living environment is perfectly cold, safe, and comfortable.

Here’s what we’ll be covering in this air conditioner maintenance guide:

  • What is a HVAC System?
  • Why Does HVAC Need Maintenance?
  • Learning About Your HVAC System
  • HVAC Maintenance — What You Can DIY
  • HVAC Maintenance — When You Should Call A Professional
  • Frequently Asked Questions

What is a HVAC System?

For a homeowner that has only recently moved into a more modern house — you may have heard about HVAC, but aren’t sure what it means. HVAC stands for heating, ventilation, and air conditioning. Each of these components may be found separately, but more than 60% of U.S. homes have a combined system that offers centralized heating and cooling.

If your home has a combined HVAC system, then the entire system may need to be targeted in order to perform efficient maintenance that keeps your air conditioner durable and functioning.

Why Does a HVAC System Need Maintenance?

Just like with a car and most other machines, a HVAC system requires regular maintenance in order to run smoothly and without hiccups. By taking regular care of your HVAC system, you’ll be doing yourself a favor in the long run. That’s because regular maintenance will extend the life of your AC unit, and can save you the hassle of an unexpected total breakdown.

 Further, a poorly maintained HVAC system decreases the efficiency of the system itself. For instance, let’s talk about something as simple as dirt. If there’s a dirt buildup, your HVAC system will end up being clogged. This blockage makes your HVAC system work harder without improving the rate in which the room cools down at all!

Dirt is only one of many things that can be detrimental to your HVAC system — which is exactly why HVAC systems need regular maintenance.

Benefits of Routine HVAC Maintenance

There are other benefits to routine HVAC maintenance than just increased efficiency and preventing damage. Here’s what they are:

Improved safety — One of the major reasons for regular HVAC maintenance is to make sure that equipment is safe to operate. Things like structural integrity, fire hazards, and loose wiring can lead to dangerous situations. Both DIY and professional maintenance can promote a safer environment for you and your family.

Cheaper repair bills — A total breakdown means that you’ll have to purchase a new HVAC system. When compared to maintenance fees, the cost of a new system can be a hundred-fold more expensive. Equipment simply lasts longer when you take good care of them.

Saving on utility bills — As mentioned, HVAC maintenance increases efficiency. Not only will that speed up the rate in which a room becomes cool, but increased efficiency means less energy usage. Saving on utility bills each month will eventually add up to a substantial amount of money.

All You Need To Know About Air Conditioner Maintenance

Learning About Your HVAC System

There’s one step we need to take before we can get into the hands-on part of air conditioner maintenance. We must learn about our HVAC system before forming our maintenance plan to ensure effectiveness and accuracy. By not under or over performing maintenance, we can deter risks without spending unnecessary time, effort, and money.

When learning about your HVAC system, here are specifics to focus on:

  • The amount of time the HVAC system has been in use
  • How advanced the HVAC system is
  • Best practices for maintenance periods
  • The average run time of the system per day

The Amount of Time the HVAC System Has Been in Use

The older the HVAC system, the more maintenance that will be required per year. As a general rule of thumb, you should perform DIY maintenance or get your HVAC system checked by a professional at least once a year.

If a HVAC system was installed before you moved in, here’s how you can check the installation date:

First, look for the condenser nameplate — On the condenser box of your unit (which is often found outside your house), the upper-right corner of the box will usually have a nameplate. On the nameplate, you’ll be able to find information like the brand, model, serial and manufacturer date.

 Decode the manufacturer date — To translate the manufacturer date to a real time, you’ll need to interpret the serial or model number. This can be easily done by visiting a website like Builder Center or a decoder available online. Call customer support or the manufacturer’s office for assistance if needed.

How Advanced the HVAC System Is

To the average person, it’s hard to gauge how advanced a HVAC system really is. Sure, you can pick up a book and try to learn — but Miller’s Heating & Air is always available to help! With a wide range of knowledge on models and brands across the industry, we’re equipped to help every homeowner.

Best Practices For Maintenance Periods

Besides the age of the model, each HVAC system will require unique intervals between maintenance periods. Your best bet to find these best practices would be through the manuals that were initially provided for your model.

As mentioned, if your air conditioning is combined into one central HVAC system, you’ll want to take note of every manual that makes up your system. The manuals to read through include the ones for your boiler, chiller, air handler, motor, thermostat, and pretty much everything else. Finding these perfect intervals will serve as the framework for the rest of your maintenance plan and as a good starting point.

If you don’t have the manual, you can call the manufacturer’s office for more information or look online for a copy of a specific manual.

The Average Run Time of the System Per Day

The last factor to take into account is how much the HVAC system is running. If the HVAC unit is present at an office building or store, you would expect much more runtime than one found in a typical house.

The longer the runtime per day, the more often you’ll need to clean or get your unit inspected.

Air Conditioner Maintenance

HVAC Maintenance — What You Can DIY

Simple DIY maintenance can go a long way when it comes to protecting your system. You can do simple things to be sure your HVAC system is up and running smoothly. Making sure ducts are clean on the exterior, checking for big leaks in the visible ductwork. Changing the air filter and making sure the system is functioning well when in use. Making notes of small issues and things that would improve the performance of the system. All this so when a technician does an inspection all the little things have been taken care of.

HVAC Maintenance — When You Should Call A Professional

Because HVAC systems are machinery with their own complexities — there’s a limit to what you can do yourself. Here are the signs and scenarios in which you should leave it to the professionals.

When You Can’t Pinpoint the Problem

Perhaps, your house is suddenly taking forever to reach a comfortable and cool temperature. Or, maybe, your electricity bills are skyrocketing for no apparent reason. It’s normal to not have all the answers. Sometimes, you’ll be able to find the solution after searching online, but that’s not always a guarantee. That’s where Miller’s Heating & Air can help you! With whatever HVAC problem you’re having, we’re the best professionals based in Portland and Vancouver.

Compressor Short-Cycling

Not only is short-cycling a symptom of a problem, but it can cause problems as well. Without addressing both the root problem and the short-cycling, you’ll find your HVAC system needing replacement much sooner than normal. That’s because short-cycling puts an intense strain on your compressor unit.

Homeowners are unlikely to find a solution for a short-cycling compressor on their own since there are many probable areas that may be at fault. Tinkering with the wrong HVAC component will be a waste of time and may cause further complications.

Electrical Issues

When you peek inside an air conditioner, there are tens or hundreds of intertwined wires, motors, and tubes. Being such a complex system, an amateur should avoid the temptation to check electrical faults by themselves. In the long run, faulty rewiring can lead to short circuits that can cause substantial damage.

Regular Inspections and Maintenance

There’s a difference between taking care of day-to-day tasks and performing a diagnostic maintenance inspection. Not only do professionals have the expertise and experience to perform an accurate inspection, but they have tools that you most likely don’t have access to. Professionals also won’t overlook things that may eventually lead to substantial damage.

Frequently Asked Questions

When to Replace Rather Than Repair?

As recommended by the Department of Energy, a HVAC system should be replaced between 10 and 15 years of use. At that age, maintenance may not be sufficient as parts deteriorate with use. Replacements may involve a single component or the entire system. Before buying an entirely new HVAC system, make sure to contact a Miller’s Heating & Air for a check-in.

How Long Does HVAC Maintenance Take?

On average, an annual or bi-annual HVAC maintenance session will take 1 to 2 hours to complete. If a HVAC maintenance has not been performed in several years, expect the appointment to be at least 2 hours.

How Can I Reduce Energy Bills?

One of the most practical ways to reduce unexpectedly high energy bills (that have no other explanation) would be to get your HVAC system tested. When a HVAC system is regularly maintained, less energy is required to keep the unit properly functioning.

How Often Do Air Filters Need to Be Switched Out?

The longer that an air filter is in place, the more dirt and debris that will build up. As a general rule of thumb, you will want to replace pleated air filters and furnace filters every 3 months. For thicker filters (MERV 8 and up), they can be replaced less often, but at least once every 6 months.

Have Fun and Stay Cool

Summers are prime time for lots of fun and excitement. The last thing you should have to worry about is returning home to a sweltering room that has no air conditioning. We encourage you to get your HVAC system regularly maintained so that you can save yourself time, money, and excessive sweating! Have fun, stay cool, and please reach out to Miller’s Heating & Air if you need to talk to a licensed HVAC technician today.

45 thoughts on “6 Toxic Air Conditioning Smells and What They Mean

  1. We have a portable air conditioner until 12 BTU when it’s on it draws the smell of creditor in the house.. we have a wood forced air furnace.
    How ca we solve the problem

    Many thanks

    Jen

    1. Hi Jen,

      Unfortunately, we do not service portable AC units. We recommend contacting an HVAC contractor in your area who does.

    1. Hi Dee,

      We actually don’t work on window AC units. We recommend calling other HVAC companies in your area to see who does.

  2. I have an odor in my home that smells like sulfur and sometimes the odor is like a ginger with onion smell, cause at times it causes my eyes to burn, occasionally nose runs a little, it also makes me cough every now and then. The smell gets really bad when I run my hvac. It’s a central unit. Some when I run my hot water seems like it’s coming through my drains,had my water company to check things out it’s not the problem.

    1. Hi Mary,

      Your HVAC system smelling of rotten eggs or sulfur most likely indicates a natural gas leak. Although on its own, natural gas is odorless, most utility providers add the aroma to alert people of a dangerous leak. Don’t take this lightly. If you smell a rotten-egg-like odor in your home, natural gas is likely the culprit, and immediate inspection is a must. While low level exposure is not hazardous to your health, high levels reduce oxygen in the blood, and can lead to loss of consciousness and death. Gas is also highly flammable and explosive, resulting in dozens of deaths each year. If you notice this smell, open the windows to your home right away, get out of the house immediately, then call the gas company.

    1. Hi Mick,

      An air conditioner smells like mildew or mold is probably the most common symptom of central HVAC systems. When the air conditioning is running, there is a lot of condensation within the unit. When the moisture doesn’t drain properly, it can escape into the ducts and create mold. Finding where the mold buildup is and getting it cleaned up will solve the problem. An HVAC repair technician has the knowledge to handle the problem and ensure that it doesn’t occur again. Note: Mold and mildew smells are not serious problems with the unit, but the poor air quality does increase the risk of respiratory infections in both children and adults. You can still use the unit while you’re waiting for repairs, but you shouldn’t put it off for the sake of your family’s health.

    1. Hi Lisa,

      We do not work on window ACs. However, if it is smelling like gas we recommend that you turn it off to protect your healthy until you have a professional come out to inspect it.

    2. My ac smelt like a gassy smell chemical of some sort i called matenace and told them i was smelling something… He said nothing he can do tonight just shut it off, Be there by 8am. i felt kinda disoriented..my friend shared this ad to me and it helped me feel so much better you really have the answers and i thank you so much !! Marie Dillon youngstown ohio….. T Y.

      1. Hi Marie,

        We are glad you found this article helpful and hope maintenance was able to fix the situation for you. If you do smell gas again, turn off your HVAC system in order to protect your health until a professional can look at it.

  3. My home smells like a car or vehicle with a really bad exhaust leak. Its really strong like oil or fuel burning thru an exhaust leak on a vehicle. What could it be??

    1. Hi Shelly,

      Even in HVAC systems not powered by gas, exhaust fumes can still result if fluids leak from essential components. To avoid a dangerous situation, have your system professionally assessed. Burning oil and other fluids can release large amounts of toxic gases, different in chemical makeup than in natural, liquid form. These particulates can be hazardous to your health, depleting oxygen and resulting in an array of health issues.

    2. My AC unit smells like the tip of a match. The red part. Not sure why or what but is this ok to run until the smell burns off? Or will it?

      1. Hi Nickie,

        Is this the first time using your unit in a while? If so, we recommend letting it run for 20-30 minutes to see if the smell goes away. If it does go away, it probably was dust on your unit burning off. However if the smell continues please contact your local HVAC company so a professional technician can assess your system. If you are in the Vancouver, WA or North Portland, OR area we would be happy to help if the smell persists!

    1. When you say it smells moth balls do you mean that it smells moldy or musty? If so, an air conditioner smells like mildew or mold is probably the most common symptom of central HVAC systems. When the air conditioning is running, there is a lot of condensation within the unit. When the moisture doesn’t drain properly, it can escape into the ducts and create mold. Finding where the mold buildup is and getting it cleaned up will solve the problem. An HVAC repair technician has the knowledge to handle the problem and ensure that it doesn’t occur again. Note: Mold and mildew smells are not serious problems with the unit, but the poor air quality does increase the risk of respiratory infections in both children and adults. You can still use the unit while you’re waiting for repairs, but you shouldn’t put it off for the sake of your family’s health.

      1. Hi Sandy May, Sounds like you have a similar situation to Lukie. When you say it smells moth balls do you mean that it smells moldy or musty? If so, an air conditioner smells like mildew or mold is probably the most common symptom of central HVAC systems. When the air conditioning is running, there is a lot of condensation within the unit. When the moisture doesn’t drain properly, it can escape into the ducts and create mold. Finding where the mold buildup is and getting it cleaned up will solve the problem. An HVAC repair technician has the knowledge to handle the problem and ensure that it doesn’t occur again. Note: Mold and mildew smells are not serious problems with the unit, but the poor air quality does increase the risk of respiratory infections in both children and adults. You can still use the unit while you’re waiting for repairs, but you shouldn’t put it off for the sake of your family’s health.

  4. Hello,
    For well over (3) months, there has been a foul odor ( I would describe as a dead animal) coming from my bedroom AC vent. It was strongest (3) mos ago, for the first (2) days it was unbearable. The latter few mos, it would come and go. I have removed the vent and inspected for animals but found nothing? Oddly, even at its strongest, it is unnoticeable once the AC is running? Any suggestions? Thanks

    1. That is an unusual situation. Normally when our customers smell something like that there is a dead animal within the duct work. Where do you live? If you are in the Vancouver, WA and/or North Portland, OR area we can have one of our technicians come out to inspect your system.

  5. Hi
    There is a odor coming from my Air Conditioner Unit, that smells like musty or someone’s butt that hasn’t washed! I have been smelling it for at least a week or more! I am a asthmatic it causes me to cough and I feel nauseous at times. How do I solve this problem! Upon turning it off I looked inside I do see mold spots.

    1. An air conditioner smells like mildew or mold is probably the most common symptom of central HVAC systems. When the air conditioning is running, there is a lot of condensation within the unit. When the moisture doesn’t drain properly, it can escape into the ducts and create mold. Finding where the mold buildup is and getting it cleaned up will solve the problem. An HVAC repair technician has the knowledge to handle the problem and ensure that it doesn’t occur again. It’s also important to keep up on annual maintenances of your system in order to keep the indoor and outdoor units clean of mold and dirt.

  6. There is like a rubber smell or electrical coming from the vent. Was checked and nothing was found

    1. Electrical odors could indicate a mechanical problem with your AC fan or compressor, wiring issues, or electrical component failure. Made with a variety of metals and chemicals, prolonged exposure to these fumes is not healthy. The first few times the unit kicks on, it may emit a burning odor that can smell electrical and dusty, give it 20 to 30 minutes and see if the smell dissipates. If it does, it probably was just the dust burning off. If it continues, contact a professional HVAC technician to check out the problem and make repairs. An electrical odor typically is a problem within the motor or the wiring. Attempting to fix either of these items can result in severe injuries.

  7. We had a new central air unit and furnace installed today. I keep smelling something. Its aerosol type smell. Kind of like spray paint.

    1. Hi Patti,

      I would recommend calling the HVAC company that installed your new central air and furnace and explain what you are smelling. Since you just had it installed, it should be free for them to come out and make sure everything is ok with your system.

    2. That is exactly what I smell! We just had it replaced about an hour ago and the smell is making me extremely nauseous ?

  8. I have had a gas smell for several months. Called gas person in February. It ended up being my gas stove/oven per the gas company. Now that the air conditioner on, I still smell a gas smell or paint thinner and I hear an airy sound as well. Have not located the source of the airy sound. Gas people said that I am hearing the gas travel up the wall. Tested; no gas indicated. Called heating/air to do maintenance and to check as well. New roofing in the community. Could this be it. Can smell back draft from neighbor’s vehicle. Which is the problem or all?

    1. Hi JJ,

      When the HVAC company came out to do the maintenance, what did they have to say about the gas smell and airy sound that you have been hearing?

      1. They said it was the upstairs neighbor’s air conditioner. As of this week, the gas people found out that the gas smell was the gas meter and fumes from a stove that I had not cooked on in a month. I still have the air sound. Do you think it is air from a pipe that needs fixing or insulation or something stuck in the vent?

        1. It’s difficult to determine the exact cause of the air sound without investigating it in person, but I did speak to a technician and they think insulation would help.

  9. my new 4 ton heat pump began emitting a strong metallic like odor, like aluminum in ac mode. it doesn’t smell at all in heat mode. my evap coil is aluminum. is that what i’m smelling? my old unit had copper coil and i smelled nothing.

    1. Hi James,

      I checked with one of our service technicians. He said that normally that type of smell is emitted during heating mode. Your unit’s indoor coil may be leaking refrigerant, which can give off a metallic smell. We recommend having the company who installed your heat pump come out to take a look. If you are in the Vancouver, WA and/or North Portland, OR area we would be happy to help!

  10. Hi, my air conditioner had recently started to leak water, at first it was small leaks, but then in day 2 the leaks got more severe, to the point where at certain points it was dripping water, i woke up today to a small puddle on the floor under the ac unit (split). There werent any odors inside the room, but i noticed when i smelled the area of the floor where the puddle had been that it smelled like chemicals, and the puddle had a bit of a pinkish hue to it, although otherwise i have not seen the pink hue. The AC still cools as normal, but i have refrained from using it after that. What could that smell be? and is it leaking water or something else.

    1. Hi Maiz,

      I spoke with one of our service technicians. He said that it sounds like water is leaking from your system either because a condensate line is clogged or the copper line isn’t insulated and it’s dripping from there. You would need to get a service technician out to look at your equipment in order to determine the cause of the smell and to stop the water from continuing to leak. If you are in the Vancouver, WA or North Portland area we would be happy to help by sending a technician out to take a look.

  11. james cox on july 10 wrote that his 4 ton aluminum coil ac gave off an aluminum smell. my new aluminum coil 4 ton carrier heat pump does the exact same thing. metallic smell in ac, no smell in heat. my house cools really fast and i’ve had this unit for a year with no recharges. what’s going on here? just hypersensitive to aluminum sell?

    1. Hi Adriaan,

      It sounds like your system is running well and most likely doesn’t have a leak. I spoke with our Service Manager and he thought it might not even be the coil causing the smell. Often times IAQ products emit ozone which can smell metallic. Do you have any IAQ products as a part of your HVAC system? In order to further diagnose the issue, we would recommend having an HVAC company come out to take a look at it. It’s difficult to fully determine the cause of the smell without being onsite.

  12. We have 1-yr old central AC unit. It emits smell when the fan is constantly on and AC is off. When the AC turns on the smell gradually disappears. When the temperature drops to the needed one, the AC turns off and the smell reappears again. The smell is quite strong. Not the mold or musty for sure. And not the rotten eggs either. Some sort of “technical” smell. There is no smell when the fan is constantly on and the unit in the heating mode. The reason of keeping the fan constantly on during the air-conditioning hours is to prevent building mold inside the system.

    1. Hi Vlad,

      Could you explain the “technical” smell in a little more detail? Is it an electrical smell? If it is an electrical smell, it could mean you have a mechanical problem with your AC fan or compressor, wiring issues or electrical component failure. Exposure to this smell/fumes can be very unhealthy. We recommend having a local trained HVAC technician come out to your home and inspect your unit. If you are located in Vancouver, WA or Portland, OR (our service area) we would be happy to send someone out.

      1. Thanks for reply. The smell is vaguely comparable with the smell of burning transformer coils, but not exactly. I know the smell of burning transformer very well. It’s different. The same smell appeared in my previous house from AC unit after living there for 10 years. A year later I moved. And now the same smell at the new place from a brand new AC unit. Amazing. I’m going to ask the guy who installed it to drop by and chek the unit when the pandemic is over.

  13. There is a paint thinner smell coming from my AC vents in my apartment. I called the manager, but her response was not promising. Is it safe to stay in my apartment?

    1. Hi Meghan,

      We would recommend getting a professional HVAC technician out to asses your system right away. Your AC does use an assortment of chemicals in order to run; it sounds like your AC could be malfunctioning (hence the smell) and needing repair. If you are in the Vancouver, WA and/or North Portland, OR area we would be happy to help! Our phone number is 360-695-6500.

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