The cooling coils the air comes into contact with appear to need UV-C lights on them in humid climates. That's the biggest thing. If the ducts have never been cleaned, then getting that done goes without saying. But those coils need to be cleaned, disinfected, and then UV-C light(s) installed to prevent mold & bacteria build-up in the future on them. That appears to be chiefly responsible for the dirty laundry and/or sour milk smell coming from forced-air AC systems in humid regions.
HVAC services is our go to contractor when it comes to our HVAC needs. Back in 2013, we were dealt some unforeseeable home projects, as our  HVAC was failing and needed to replace the whole system, e.g. Furnace, Blower, A/C, Condenser, Vents, etc... We reached out to a few HVAC companies (Contra Costa Heating and Air, EP builders, High Performance Heating and Air) so we could compare the bids for the job. We have had some issues with past contractors and after thoroughly screening a few of the above mentioned HVAC contractors, we awarded the bid to HVAC services because of their superior customer service and very reasonable pricing.
Simply living in your home creates dust and dirt. Have you ever seen dust floating in the air in your home when the sun shines in?  Dust, dirt, pet dander, mold spores, and allergens get pulled into the air handling system in your home. They build up in the ductwork; some of it gets recirculated back into your home, and some of it can be captured by a good quality air filter. Eventually, enough debris builds up to the point where most of it blows back into your home. Your furnace or air conditioner must run longer to cool or heat your home, which costs you more in utility bills. With a service call from Sears Air Duct Cleaning, you can feel comfortable knowing that the accumulation of dust, dirt, dander, mold, and allergens has been cleaned from your HVAC duct system.
Your HVAC unit and air ducts deliver heated or cooled air throughout your home year-in and year-out. The air your HVAC unit produces travels through your ductwork and heats or cools your home via the air vents in each room. The dust and other particles in your home’s air are known as particulate matter, which the EPA defines as "a complex mixture of extremely small particles and liquid droplets." The EPA also notes that "particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles." Having clean air ducts means fewer of these particles moving through your home. If you remove your furnace filter and hold it up to the light, you can probably see several hundred of these minuscule particles floating in the air. 

Roof-mounted systems have the heating and cooling systems in one cabinet. Sometimes called "gas packs" (if the heater uses natural gas), they typically cost less than a comparable split system. In dry regions, most homes originally had "swamp-coolers" installed. When replacing them with HVAC systems, it's often cheaper to use existing mounts and ducting.
This article was very good. It should be noted that the EPA building in Washington, DC, was cited years ago as one of the worst "sick building syndrome" buildings. Wish you had mentioned about having people's dryer vents cleaned since they can cause so many fires in homes. Most homeowners forget to check the air flow on the dryer vent. Our company, which cleans by NADCA standards, does both air ducts and dryer vents. Thanks again for keeping the public informed, especially regarding the cost of air duct cleaning...you get what you pay for...don't be fooled by the lowest cost out there. Frequently these are bait and switch companies or will keep adding on features they say a customer needs until the price is so high it's ridiculous.
Furnace Circuit Board -- The furnace circuit board controls a variety of functions. It not only handles the regular operation of the furnace, it also monitors the furnace's various safety circuits. Over time, vibrations from the furnace can weaken solder point and cause them to separate. Dirt and debris can cause short-circuits that damage the board. Failure of the circuit board can cause a variety of effects ranging from the fan not turning on to the complete shutdown of the furnace.
This company deserves more than five stars. They didn't just replace my heater and air conditioner, they built me a new system for my house. Going above and beyond is a understatement. Steve's staff were 2 of the nicest workers I've come across in a long time. Friendly, knowledgeable, and very clean. Truly a top rated company. Thanks Steve.   Great job.
I purchased a Groupon for cleaning of unlimited air ducts and one return vent for $39. I should have checked into their hours first because they only offer services during normal business hours. So, with no evenings or weekends available you have to take time off work. I asked Groupon for a refund when I realized this and they refused because it wasn’t within the three day window. Then they didn’t even show up or call for the appointment. I called them after they were an hour late and they were going to call the local dispatch office and have them call me back within 15 minutes. I did not receive that call. I called again and was told I would get a call back from a manager. That didn’t happen either. So I asked Groupon for a refund again and they gave me Groupon bucks. When the survey came asking if I was satisfied with the Groupon customer service I said no, I want real money. I got my real refund the next day. Seems to me Groupon should stop dealing with these companies.
Outdoor Fan Motor -- The outdoor fan, also called the condenser fan, is exposed to external conditions. As such it is most prone to dust and debris and the extreme weather. In desert climates, the outdoor fan motor is subject to heat not only from normal operation but from the outside temperature as well. As it starts to fail, the fan may work fine in the cooler morning hours but stop by afternoon. This can shut down the entire system for hours. When they stop running completely, your air conditioner will no longer work. Running a faulty fan will lead to compressor failure, which is a very costly repair.
First of all, I think it is great that there are many companies out there who look out for the customer and protect their interest. Secondly, I think it is also important that customers consider having their HVAC systems checked thoroughly before moving into a new home. I have heard a couple of horror stories where previous owners have not had the best housekeeping skills. Even when the appearance of the home seems it has been well kept, keep in mind that surface clean only goes so far. You can never tell what lies underneath.
On the other hand, if family members are experiencing unusual or unexplained symptoms or illnesses that you think might be related to your home environment, you should discuss the situation with your doctor. EPA has published the following publications for guidance on identifying possible indoor air quality problems and ways to prevent or fix them.
We were following up on this review and the service call we did for you. We could not find you in our system of ever having gone out to your home. If you could please provide us with the date we were out and the name under which the call was placed that would be great as we would like to see if there is any way we can rectify the situation. We do offer a 100% Satisfaction Guarantee, we have tried to private message you to no avail. Can you please call us at 925-318-4795?  
Quality and price should come hand in hand, a too-good-to-be-true price for an efficient air duct cleaning will not give you the quality that you wanted. To make sure you are getting your money’s worth, check reviews of air duct cleaning companies, certifications from industry since this work requires continuous learning due to new techniques and research breakthrough from time to time. Make sure to shop around and get written estimates first.
There are multiple reasons to replace your HVAC system. If you have built additions onto your house, you may find your old system no longer meets the requirements for the new dimensions. Perhaps a new technological breakthrough has provided features that will improve your comfort and air quality. Most often, however, you need to replace your system because it no longer works properly.
You may be familiar with air ducts that are constructed of sheet metal. However, many modern residential air duct systems are constructed of fiber glass duct board or sheet metal ducts that are lined on the inside with fiber glass duct liner. Since the early 1970's, a significant increase in the use of flexible duct, which generally is internally lined with plastic or some other type of material, has occurred.

In the United States, HVAC engineers generally are members of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), EPA Universal CFC certified (for installation and service of CFC HVAC devices), or locally engineer certified such as a Special to Chief Boilers License issued by the state or, in some jurisdictions, the city. ASHRAE is an international technical society for all individuals and organizations interested in HVAC. The Society, organized into regions, chapters, and student branches, allows exchange of HVAC knowledge and experiences for the benefit of the field's practitioners and the public. ASHRAE provides many opportunities to participate in the development of new knowledge via, for example, research and its many technical committees. These committees typically meet twice per year at the ASHRAE Annual and Winter Meetings. A popular product show, the AHR Expo, is held in conjunction with each winter meeting. The Society has approximately 50,000 members and has headquarters in Atlanta, Georgia.


1. Ducts need cleaning mostly because they were not installed properly. There should be regulatory inpection and approval of clean and proper duct works on new houses. I was extremely unpset when I looked and found significant amounts of construction dust in parts of the ducts in my new house. There is apparently no way to hold the bullder to be responsible for clean ducts.
Indoor Coil -- The indoor coil is a heat transfer device. It absorbs the heat from the inside of the house and passes it on to the refrigerant and is pumped outside. Dust that builds up on the coil can hamper its ability to absorb heat. High heat transference coils use very thin metal. Airborne chemicals can cause corrosion which leads to leaks. The constant vibration of the compressor can also cause solder joints to weaken and leak. An indoor coil may operate for weeks with a tiny leak, and you may not notice the loss in performance right away. As soon as a leak is made known, it should be replaced or repaired immediately.
The amount of debris or mold present in your system could certainly ratchet up the overall price. The cost of mildew removal is around $0.07-0.08 per square foot, on top of your initial cost, according to Blue Book. Removing these elements involves added time, special equipment and even special chemicals. In fact, you may be referred to a specialist if mildew and mold is too severe.
Internal insulation provides better acoustical (noise) control. Flexible duct is very low cost. These products are engineered specifically for use in ducts or as ducts themselves, and are tested in accordance with standards established by Underwriters Laboratories (UL), the American Society for Testing and Materials (ASTM), and the National Fire Protection Association (NFPA). Many insulated duct systems have operated for years without supporting significant mold growth. Keeping them reasonably clean and dry is generally adequate. However, there is substantial debate about whether porous insulation materials (e.g., fiber glass) are more prone to microbial contamination than bare sheet metal ducts. If enough dirt and moisture are permitted to enter the duct system, there may be no significant difference in the rate or extent of microbial growth in internally lined or bare sheet metal ducts. However, treatment of mold contamination on bare sheet metal is much easier. Cleaning and treatment with an EPA-registered biocide are possible. Once fiberglass duct liner is contaminated with mold, cleaning is not sufficient to prevent re-growth and there are no EPA-registered biocides for the treatment of porous duct materials. EPA, NADCA and NAIMA all recommend the replacement of wet or moldy fiber glass duct material.
Important Tip: Don’t just pay attention to the high-end of the price range! – which is what I know you are all looking at, but also look at the low range. If a contractor is cheaper than this, ask “why?” Usually it is because they don’t have liability insurance, workman’s compensation insurance, are unlicensed, all of the above, or worst yet, they don’t use HVAC technicians. You are spending a lot of money.  Make sure that they are licensed (In California, check here at CSLB License Checker) and insured.
Bigger is not necessarily better when it comes to HVAC systems, and smaller isn't always more efficient. If you have too small of a system, your system will be running constantly as it tries to keep up with the temperature. If you have too large of a system, it won't run long enough to keep up with the humidity. In order to handle both temperature and humidity efficiently, an HVAC system should run for around 30 minutes at a time. If your system is staying on too long or shutting off after only around 10 minutes, you are not getting efficient performance.
The jury is out on whether or not cleaning your air ducts and vents has a significant enough impact to be necessary. A proven connection between immaculate duct systems and air quality in the home has not been made. However, if your vents display any of the signs listed above, cleaning would certainly be in your best interest. Allowing mold, debris and bacteria to fester could create bigger problems down the line. If having your system disinfected is within your budget, you may prefer to take care of these issues rather than ignore them.

Our HVAC Ductwork Installation Cost Guide is the most comprehensive guide of its type. It fully explains the purpose of ductwork and all your options. Pricing is included for all duct types and plenums/drops too. Material and installation costs are listed. Ductwork cost varies greatly by the size and type of duct plus the complexity of the installation, but you can expect to pay $10.20 to $17.25 per linear foot installed.

The short answer is yes, duct cleaning, done right by a reputable company will help with the smell. It is likely though the smell is coming from another source, ie the crawl space. It could also be that another rodent is dead in the duct work. A visual inspection would be in order to check for any breach in the duct system. A duct pressure test would be able to tell you how much air is leaking from the system over all. A hole large enough for an animal to enter would loses a great deal of air, over 300 CFM. It would be worth looking into having this test done and it should cost around $200. Cleaning the air handler and evaporator coil will greatly improve the performance of the air conditioner. Dirt and dust on the evaporator acts as insulation and reduces the amount of cooling done be the coil. Any quality duct cleaning should include cleaning the air handler and coil, and the tech should allow you to watch him perform the work as it is done.
If you don't agree with duct cleaning, fine. If there are some things that HVAC people can do to make the system need cleaning less often fine, but to suggest that I need to GO TO JAIL????? If you need to knock others to make yourself look better....... If duct cleaning is such a scam, why are their governing bodies like NADCA (which I do NOT belong to),several manufacturers of equipment, and national restoration franchises (I'm not a franchise either) who provide this service? I guess the whole world is stupid and only HVAC people are smart. I suppose I am scamming them when I clean puff backs, water damage, fire damage, and clean their carpets too? Or did I wake up one morning and say "ya know, it is great to be a hard working, honest owner operator, but I would love to provide a service that unlike everything else I do is a con and rips off the 90% referral business I busted my butt to earn"
Heating, ventilation, and air conditioning (HVAC) systems have been shown to act as a collection source for a variety of contaminants that have the potential to affect health, such as mold, fungi, bacteria, and very small particles of dust. The removal of such contaminants from the HVAC system and home should be considered as one component in an overall plan to improve indoor air quality.
The HVAC industry is a worldwide enterprise, with roles including operation and maintenance, system design and construction, equipment manufacturing and sales, and in education and research. The HVAC industry was historically regulated by the manufacturers of HVAC equipment, but regulating and standards organizations such as HARDI, ASHRAE, SMACNA, ACCA, Uniform Mechanical Code, International Mechanical Code, and AMCA have been established to support the industry and encourage high standards and achievement.
The jury is out on whether or not cleaning your air ducts and vents has a significant enough impact to be necessary. A proven connection between immaculate duct systems and air quality in the home has not been made. However, if your vents display any of the signs listed above, cleaning would certainly be in your best interest. Allowing mold, debris and bacteria to fester could create bigger problems down the line. If having your system disinfected is within your budget, you may prefer to take care of these issues rather than ignore them.
Well, I had the cleaning done. The handler is definitely much quieter. It was explained to me that with the coils clean, the condensation will be able to sweat off instead of sticking to the dust and dirt, therefore the humidity (lots of humidity in florida) will be removed better. I feel as if it was worth it, but, I will definitely change that filter every 3 weeks or so from now on. I don’t want to pay that cost again.
If you are using existing ducting, it will have to be inspected. Proper ducting loses around 2% to 5% of your energy. Old, leaking ducts can lose 50% or more. A contractor will need to have the ducts inspected and replace any parts ahead of time. If you are changing the size of your HVAC system because of significant changes to your home, you might need to replace the ductwork regardless.
My father started in the business of home comfort back in 1968, an I around 1986. We still don't have a duct cleaning machine. I am sure there are always applications for all tools in this industry. However I missed where anyone talked about where dust even comes from..........We do not have these little dust machines sitting in a corner puffing out little clouds of dust....soooo where does it come from?
With the split system, the evaporator coil is connected to a remote condenser unit using refrigerant piping between an indoor and outdoor unit instead of ducting air directly from the outdoor unit. Indoor units with directional vents mount onto walls, suspended from ceilings, or fit into the ceiling. Other indoor units mount inside the ceiling cavity, so that short lengths of duct handle air from the indoor unit to vents or diffusers around the rooms.
Consider what kind of heating and cooling system you want installed for the square footage of your home. Do you want a full system with a thermostat or a specific machine for the summer like a swamp cooler? Do you need a new furnace just for the winter? For any of these projects, the cost will vary depending on the quality, style and machine size you choose. If you have a tight budget, think of going smaller and upgrading over time. For example, if you can't afford to convert your entire home to solar power, you may want to consider only utilizing it to heat your water. Some other types of heating systems are:
An important component of natural ventilation is air change rate or air changes per hour: the hourly rate of ventilation divided by the volume of the space. For example, six air changes per hour means an amount of new air, equal to the volume of the space, is added every ten minutes. For human comfort, a minimum of four air changes per hour is typical, though warehouses might have only two. Too high of an air change rate may be uncomfortable, akin to a wind tunnel which have thousands of changes per hour. The highest air change rates are for crowded spaces, bars, night clubs, commercial kitchens at around 30 to 50 air changes per hour.[17]
Demand controlled kitchen ventilation (DCKV) is a building controls approach of controlling the volume of kitchen exhaust and supply air in response to the actual cooking loads in a commercial kitchen. Traditional commercial kitchen ventilation systems operate at 100% fan speed independent of the volume of cooking activity and DCKV technology changes that to provide significant fan energy and conditioned air savings. By deploying smart sensing technology, both the exhaust and supply fans can be controlled to capitalize on the affinity laws for motor energy savings, reduce makeup air heating and cooling energy, increasing safety and reducing ambient kitchen noise levels.[29]

HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels and senior living facilities, medium to large industrial and office buildings such as skyscrapers and hospitals, vehicles such as cars, trains, airplanes, ships and submarines, and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.
Bigger is not necessarily better when it comes to HVAC systems, and smaller isn't always more efficient. If you have too small of a system, your system will be running constantly as it tries to keep up with the temperature. If you have too large of a system, it won't run long enough to keep up with the humidity. In order to handle both temperature and humidity efficiently, an HVAC system should run for around 30 minutes at a time. If your system is staying on too long or shutting off after only around 10 minutes, you are not getting efficient performance.
I guess, I will start with saying that air duct cleaning is almost never needed. It is not a scam, but it is certainly something that uneducated homeowners get suckered into. In regards to air flow, a well balanced HVAC system should be able to deliver more than enough air flow. If you are not getting good air flow, it's because your system may be out of balance. Additionally, regular cleaning/changing of the air filters will solve about 95% of your problem. Though you would be surprised how many people either a. don't have a filter or b. don't know about it and leave it there for 10+years. a washable one should be cleaned every 6 months(spring and fall) and a disposable one should be replaced every 3-4 months.
Just had my HVAC System restored and working again on a Sunday and before the 104 weather tomorrow!!!! Called Big Mountain Heating and Air and spoke to very helpful woman named Martina. She connected me to a Technician named Josh. He was at my home within a few minutes and tackled my Honey Well system's issues. He is both skilled, personable and better yet, he got my system up and going and safe. He installed a surge suppressor on the system to prevent power surges that can kick off any system, when the electric company has to reduce power, etc.  I will be using Big Mountain in the future. Truly grateful for such good service and people. Thank you!  I recommend this firm to everyone!
Pro Tips: Before you buy one of the learning thermostats available, you should beware of their shortcomings. First, many require a c-wire to work properly. A common problem is that the old thermostat might not use a c-wire, and this makes it confusing when swapping wires to the new thermostat. Secondly, if you change your thermostat setting often, you might become frustrated with a nest thermostat or other learning thermostat. It will be constantly trying to learn patterns in your random setting changes, and will therefore change your home’s temperature when you don’t want it to. If you have a fairly consistent schedule or don’t mind overriding the unit either manually or via the app on your way home or when leaving, then you won’t experience this issue.
Do not hire duct cleaners who make sweeping claims about the health benefits of duct cleaning — such claims are unsubstantiated. Do not hire duct cleaners who recommend duct cleaning as a routine part of your heating and cooling system maintenance. You should also be wary of duct cleaners who claim to be certified by EPA. Note: EPA neither establishes duct cleaning standards nor certifies, endorses, or approves duct cleaning companies.
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