The liquid refrigerant is returned to another heat exchanger where it is allowed to evaporate, hence the heat exchanger is often called an evaporating coil or evaporator. As the liquid refrigerant evaporates it absorbs energy (heat) from the inside air, returns to the compressor, and repeats the cycle. In the process, heat is absorbed from indoors and transferred outdoors, resulting in cooling of the building.
You can adjust for seasons: During the summer, you can have the air conditioner stay off during the cooler morning hours and start cooling the house as everyone gets up and starts moving around. During the winter, you can have your heater stay off while you are away at work and turn on about a half hour or so before you get home so that you are coming home to a nice, warm house.
My 48 yr old house (mine for the last 4 yrs) has considerable dust in the return plenum (fiber duct). I’m remodeling and recently re-sealed the return plenum AND the site-fabbed transition built when the new unit was installed, 2013. The return was leaky no doubt drawing musty, dusty air from the crawl space due to the Red-Neck fab & seal job! Pitiful craftsmanship! It took me 7 hours to fix the new transition piece. Anyway, the dust in the house is the same “color” as whats in the return duct and I’m getting way too much & too often in the house. I’ve also cleaned my coils, which were not that dirty.

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.
Air conditioning units are prone to the pitfalls of wear and tear. You can prolong this, however, with proper maintenance procedures. Without regular maintenance even an immaculate AC installation in Fort Smith, Arkansas cannot guarantee performance. Our maintenance service is thorough, leaving no area unattended. If there’s a problem, we’ll catch it early and prevent avoidable breakdowns and costly repairs.
We divided new HVAC installation cost into three groups: first, the Change-Out, which is an installation of just your HVAC components without the ductwork; Full Installation, which is the installation of all HVAC equipment including ductwork; and finally, Full Installation with Features, which is a full installation with additional features such as a zoning system or media filter with a complimentary Ferrari Portofino.
Since the 1980s, manufacturers of HVAC equipment have been making an effort to make the systems they manufacture more efficient. This was originally driven by rising energy costs, and has more recently been driven by increased awareness of environmental issues. Additionally, improvements to the HVAC system efficiency can also help increase occupant health and productivity.[23] In the US, the EPA has imposed tighter restrictions over the years. There are several methods for making HVAC systems more efficient.
Here in Atlanta we get 6 to 10 $49 coupons in the mail weekly…I have always consider them a complete scam….just had my master bathroom& bedroom and guest bath completely remodeled down to the studs…Had my 3 returns nearest the area sealed to prevent sheet rock dust to spread…it worked and I personally cleaned all 7 returns when a 5 HP , new Rigid shop Vac($99 from HD)…took one hour and I found little evidence that “I need my ducts cleaned” Had quotes from $400 to $600…I use the best air filters for my air handler and change it every 2 to 3 months…..any dust is trapped in it and I believe the Air Duct folks are all cons….
Alberto said they were busy but could either install on the upcoming Saturday.  We were going to be out of town and said unfortunately that day did not work.  He then proposed the upcoming Tuesday as a possible solution, but just had to confirm with another appointment.  I said great.  I will review the estimate and call your office to confirm I want to move forward with the install.
I am very interested by your post. We recently had a lead inspection on our property and one thing the lead inspector suggested was to get the air ducts cleaned out. We had our ducts cleaned last year after we under went a large renovation project (since we have a toddler in the house). This year we decided to go for lead compliance and had all our lead removed (we moved out for the work). Recently, my son had a false positive lead test, which prompted us to get a lead dust inspection around the house (including having the vents dust-wiped on the inside). The levels inside the ducts weren't crazy high (but more than would be acceptable for a floor). As it turned out my son's lead levels are very low (but not zero). Is it possible however that lead dust from the inside of a vent can come out? Would this be a scenario where you think air duct cleaning would be beneficial?
As you can see, if we know what the contractor is actually paying for specific equipment, we know what their labor rates are, and we know what they bid the project for, then we can also use some basic algebra (or just let the program do it for us because we’re lazy) to figure out how much of a profit they are making off of us (you) at different bid prices:
Reinstall the access panel and disconnect block. Turn on the circuit breaker and furnace switch. Then set the thermostat to a lower temperature and wait for the AC to start (see “Be Patient at Startup,” below). The compressor should run and the condenser fan should spin. If the compressor starts but the fan doesn't, the fan motor is most likely shot. Shut off the power and remove the screws around the condenser cover. Lift the cover and remove the fan blade and motor (Photo 7). Reinstall the blade and secure the cover. Then repower the unit and see if the fan starts. If it doesn't, you've given it your best shot—it's time to call a pro.
The number of years an HVAC system lasts depend on the type and brand of components that make up your system. The lifespan of an air conditioner averages between 15 and 20 years. The life expectancy of a tankless water heater is approximately 20 years, while a storage water heater is closer to 10-15 years. Ducts may need replacing within 10-15 years. Your equipment will have a longer life if you have regular tuneups and maintenance to keep everything in good working order. If you’re having repair problems and your HVAC system is over 10 years old, it’s a good time to consider the costs and benefits of repairing vs. replacing. Energystar.gov provides the following tips to help you decide whether to repair or replace:
Despite Bergendahl's experience, Vinick says NADCA's certification standards have improved the situation. "A lot of [service companies] weren't going about it the correct way," he says. “We have an anti-fraud task force, and we’ve gone after some fraudulent duct cleaners with the help of state attorneys general.” He suggests that in addition to NADCA membership, homeowners make sure their cleaners are an established business, have appropriate insurance and are registered to do business in their state and locality.
I just bought a home, and the sellers clearly never had the air ducts cleaned. This is, unfortunately, typical of their neglect of the home, so I am not surprised. I was cleaning around the wooden floor registers, and I took the registers off. I found nests of some sort...all kinds of really gross stuff!! I am calling now to schedule duct cleaning for my new home. Anyway, it is very easy to check to see if you really need duct cleaning. Remove the floor registers and use a flashlight if necessary to see if there is dust or debris in the ducting. If these look bad, I'd definitely have the system cleaned. I would also do it after a construction project, after installing a new furnace, etc. I have found that once I had my previous system cleaned, it seemed to remain spotless for 3 years. So it seems that if you just change your filters on time (I have an iPhone alert set for every 3 months), the system will stay clean for years. Hope this helps!
I even asked if this is something they don't do, as in services on a Saturday night.  I was told by the receptionist that they do and I would just be ok calling another company if they is not  part of their services. They again assured me someone WILL call me in 10 mins.  Well, unless their definition of 10 mins is never, then they got it wrong as I am still waiting to be called 5 days later.
There are many interesting comments from several informed individuals. The question that has not been answered is how do duct systems get dusty and dirty? As a RESNET Home Energy Rater, I perform pressure tests on homes and duct systems, and the one common thread is . . . most air delivery sytems have large amounts of air leakage. The solution is to seal the duct system, and pay particular attention to the return duct system and ductwork near the air handler (the 'blower'). As others have said, a captive (sealed) duct system with proper filter maintenance should be more then adequate for most occupants. For those who have allergy, asthma, or other breathing problems, a filter with a higher MERV rating (number should be listed on the package) or a HEPA filter are good choices. These filters will capture smaller particulates and should improve the indoor air quality. Again, make certain that the entire duct system is sealed, preferably with mastic, second choice UL-181 foil tape - never use cloth duct (also known as duck) tape.

20 yrs ago I bought the house I am in and a Central H/A was installed at that time. At the beginning of ea season I have the unit serviced. Every yr since I have owned the house I have had to have freon added and been told that I must have a freon leak. Fast forward to this yr when I hired a new company to do the service. They went up into the attic as part of their overall servicing. Nobody else has ever done that. He came down showing me pics on his camera phone of ducts that were not even connected to anything and in my estimation have probably been laying there for 20 yrs. Of course he fixed this. I have not needed freon this year either. I have been complaining to friends about the huge amount of dust and how I can't keep up with the cleaning away of it for a long time. Now it makes so much sense.To me it is like that duct work was just up there laying around and every time my unit was blowing, all the insulation, debris, dust and whatever else over the years was just randomly filling up those ducts. What now that they are re-connected? Will it be better? Or am I someone that needs to have my ducts cleaned? I am so confused after reading all these comments. Can one of you experts tell me what you would do before I spend a bunch of money that I don't really have? Thank you for any input you can provide. Also, feel free to respond to email address denise@digitalflak.com

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.
A Full Installation is the most common type of HVAC installation for a reputable contractor. The ductwork adds two days of labor and about $2,000 to $3,000 to the price, but realize that this is a very important part of your HVAC system. Although it might sound like a good idea to reduce HVAC installation cost and get a quick change-out, realize that there is dirt and debris collecting in your ducts, and the ducts themselves develop holes and full breaks over the lifetime of your unit, all of which may be hidden from sight by insulation. Remember, many contractors will push a quick change-out on you because it is easy and good money for them – you need to be involved and ask questions.

On the other hand, if a service provider fails to follow proper duct cleaning procedures, duct cleaning can cause indoor air problems. For example, an inadequate vacuum collection system can release more dust, dirt and other contaminants than if you had left the ducts alone. A careless or inadequately trained service provider can damage your ducts or heating and cooling system, possibly increasing your heating and air conditioning costs or forcing you to undertake difficult and costly repairs or replacements.

The cost to replace a central air conditioner is about $5,000. However, this price varies depending on the size of your home and the difficulty of the project. It can cost as much as $12,500 to replace an AC unit. The labor required to remove and dispose of the old system adds to the price. The size of your home, brand of AC unit and ductwork complexity can all raise the cost as well.


Hello, I read your comment and I know it was two years ago but I hope you see my message. I am trying to figure out what to do as I was told that there is some cat odor in the finished basement. I think with the air conditioning running that it may carry odor. The litter boxes are always kept clean. I wonder if odor can be trapped in the ducts, if Air Duct Cleaning could help, but it is quite expensive plus I'm concerned that it may not help. Please elaborate as to why you think it doesn't work that well. Do you have any other advise? Did you work in the field of Air Duct Cleaning? Thanks so much!
The EPA is so far behind on useful knowledge because of the lack of funding so don't be mislead. The Hvac old timers were left at the dock so to speak and missed out on the IAQ movement. The ones that are savvy and up to date on the information do Air Duct Cleaning, even tho that will lead to a few less service calls its the right thing to do for their customer. Please take a look into a return duct that has never been cleaned, I dare anyone to say it does not need to be cleaned.
My heat pump/hvac system is not blowing cold air anymore, got checked out was told compressor broken. was told it cost  almost the same to repair/replace they recommend whole system. It's the same company that installed it 18 years ago, telling me that system is old and it will cost $9-10k for new system, because furnace has to be replaced with new hvac. what to do, need answers thanks????
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