During the summer, your air conditioner (AC) works harder and longer. That high demand may cause a problem to rear its ugly head. In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.
Noises
While your AC is running, you should hear the hum of the blower, a click when your air conditioner turns on, and the whir of the outside condenser fan. Other noises – such as rattling, screeching, thumping, clanging, or banging – mean your system is having problems. Typical causes of noise from the AC unit include: a belt wearing out, loose hardware, a failing motor, refrigerant issues, or blower issues. But try these things first: make sure the filter is clean, that the air vents in all rooms are unblocked, and that there are no obstructions around or in the outside unit. If you still hear strange noises, contact a professional AC service technician before the situation worsens and leads to big repair bills and prolonged downtime.
Avoid AC Problems
Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it. Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat. If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.
During the summer, your air conditioner (AC) works harder and longer. That high demand may cause a problem to rear its ugly head. In this multi-part post, we’ll take a look at some of the most common AC problems, talk about the possible causes, and provide suggestions for tackling each problem.
External Fan (Compressor) Not Working
Check all around and inside the outdoor unit. Verify that the fan blades are unimpeded. It could be that the outdoor unit sustained damage due to falling debris from storms. Be sure to keep the area around the outdoor unit clear of debris and check it often throughout the summer and fall. If there are no obstructions and the fan blades are not turning, it could be caused by a lack of power to the system. Cycle the power by turning the circuit breaker off and back on again, then set the thermostat lower than the current inside temperature and wait 2-5 minutes. If you do not hear the compressor kick in and the fan blades start to turn, you probably have a faulty motor or compressor, and will need to contact a service professional.
Avoid Summer AC Problems
Summer can be the best time of the year, so don’t let air conditioning problems hinder you from enjoying it. Be sure to get annual AC maintenance visits, so it will run efficiently and be ready for the high demand of the summer’s heat. If you live in the Nashville area and experience any heating or cooling problems, call on Interstate AC Service at (615) 832-8500.
The long, humid summers in Middle Tennessee are conducive to mold and mildew and its associated odors forming in your home. In this post, we’ll help you get to the bottom of any mold issues you may have and alleviate this smelly and potentially hazardous problem.
What is Mold?
Mold is a microscopic fungus that travels as spores in the air and dust all around us – inside and outside. It thrives in moisture and easily builds colonies. Mold can cause health problems for you and your family – such as sinus, allergy, and respiratory issues. Some molds produce deadly mycotoxins – the so-called “toxic molds” or “black mold” – which can cause neurological issues and even death. Contrary to popular belief, not all black-colored mold is the toxic type, and not all strains of toxic molds are black-colored. However, anytime you see mold, it bears investigation.
Causes & Prevention
To begin ridding your home of the foul odors and health hazards caused by mold and mildew – and to prevent them from re-occurring – here are some things you can do:
Change air filters. If you have not been changing your air filter on a regular basis, change it! Your system’s filter pulls odor-causing contaminants out of the air and if the filter is overloaded, the captured contaminants could be recirculating back into your home when the air conditioner is in use.
Clean-up the environment. Since mold spores are most prevalent in dust, be sure to vacuum and clean your surroundings regularly, including changing linens. Use exhaust fans while showering and cooking to dissipate humidity as needed.
Fix leaks & replace seals. Make sure there are no active leaks around appliances and plumbing, in the basement, crawl space, and roof. Replace the seals around the tub, shower, or windows where moisture collects. If there was ever a flood where the carpet, flooring, or drywall got wet, don’t just “let it dry” – get it replaced! This can be a particular problem in Nashville, where so many houses were damaged in the 2010 floods, or experienced a burst pipe or ice damming in the winter which caused interior flooding.
Fix drainage issues. Check for any standing water or drainage issues around the foundation of your home. This may be due to landscaping or erosion issues, or to faulty gutters. Get the basement waterproofed or install a sump pump, if necessary. See our video Excess Humidity: Causes & Solutions.
Service the HVAC system. During a spring/summer HVAC maintenance visit, the evaporator coil and condensation lines are cleaned. This is crucial, since a condensate drip pan is the perfect environment for mold and algae growth and is the second leading cause of AC failure. See our video Clean Condensate Drain Lines to Prevent Mold.
Check the ductwork. If you turn off your HVAC system and wait 20 minutes and the mildew smell or foul odor seems to dissipate, and returns when the system is back on, that could be a sign that the problem lies in your ductwork. Moisture and odors can enter the ductwork through a tear, gap, or hole in the duct, and then circulate through your home. In some cases, duct cleaning or replacing the ductwork may be necessary, but if caught early, just re-sealing the duct may do the trick.
Test. Buy a home mold testing kit – easily obtainable at local hardware and home supply stores for under $10. Get at least one test kit per floor, and a separate one for the basement. After setting up the kit in the house for the required length of time (usually a few days), mail it off to a testing lab to find out what types of molds are present and whether there is cause for concern (note: a lab testing fee of about $40 may apply). If you’re buying a new or pre-owned home, get a professional mold inspection from a reputable company with appropriate certifications.
Removal & remediation. Mold removal and remediation is a specialty of its own, and not something a homeowner should attempt themselves. It requires specialized training, equipment, chemicals, and wearing of personal protection devices. Use only companies that are specifically certified and licensed for this type of work.
If you care about the quality of the air you and your family breathes every day – and want to prolong your HVAC investment – call on Interstate AC Service at 615-802-2665. We’re here to help with all your heating and air-conditioning needs.
Perhaps you’re really handy around the house, and enjoy taking on fix-it projects. Adding refrigerant to your HVAC system – what we call a “shot of Freon” – is definitely NOT a do-it-yourself task!
Iced Up!
When your air conditioner is low on Freon, it means this colorless gas is leaking out from somewhere in the system (see Causes of Refrigerant Leaks). Typically, you will see ice forming on either the inside or outside unit or both. If this happens you need to turn the HVAC system off completely, wait for it to thaw out, and call an HVAC professional.
Not DIY
Here are just some of the many reasons why you cannot just “add a shot of Freon” to your AC yourself:
Possessing most refrigerants – which are toxic chemicals – requires a special EPA 608 certification, which typically only licensed HVAC contractors can get. It is unlawful to possess HVAC refrigerants without such a license. If you find a seller that will sell directly to a consumer and does not ask for your 608 certification, then you should be suspicious that what they’re selling is counterfeit (see our post Fighting Back Against Fake Refrigerants).
There are now many different type of refrigerants on the market and each unit will work with only a certain type. Putting the wrong type of refrigerant in your unit will damage the unit, and could also cause significant hazard to you! Furthermore, as one refrigerant (R-22) has been phased out of production, other refrigerants may be used in its place, but may require certain updates to your system in order to do so. You cannot assume that a supposedly “equivalent” product is compatible with your system.
To replace the leaky part or to update the refrigerant, the “old” refrigerant needs to be evacuated first. But this cannot be done simply by exhausting it into the air (it is unlawful to do so)! It must be captured into a special pressurized container so it can be recycled. Keep in mind that refrigerants are gasses at room temperature, and are compressed under extraordinary pressures in order to liquefy. Special gear is required to diagnose where the leak is, and to evacuate the old refrigerant and fill with new refrigerant. Purchasing the appropriate gauges, diagnostic equipment, and pressurized vessels would exceed the cost of the service call.
Depending on the source and extent of the leak, it may be better and more cost-efficient to replace the entire unit, rather than to continue to fill it with Freon that will only leak out again in a short time. Sure, the cost to repair or replace your system may be higher than simply adding another “shot of Freon,” but not addressing the cause of the leak causes recurring expenses that will only escalate. For example, recharging the system several times could cause the oil in the compressor to deplete enough to damage the compressor, and then you may require a major, really expensive repair!
Are You Cost-Conscious?
The bottom line is this: if you’re cost conscious, then the best “bargain” is calling an HVAC professional when your system needs a shot of Freon.
If you live in the Nashville area, call Interstate AC Service at 615-802-2665. We’ll help you with whatever ails your HVAC system.
Foul odors coming from your cooling system are more than an unwelcome inconvenience – they can be downright dangerous. Air conditioner smells are most often caused by mold and mildew growing somewhere within the system. In this post, we’ll look at how your HVAC system can harbor mold and be responsible for circulating musty odors.
Air conditioners work primarily by dehumidifying the air. The water drawn out of the air drips from the evaporator coils into a condensation pan (or drip pan) under the HVAC air handling unit. Drip pans are the perfect environments for mold and algae growth, which then can clog the drain lines. If the moisture is unable to flow out of the system, the water backs up and can overflow the drip pan, causing water damage in your home as well as causing your air conditioner to shut off. In fact, a clogged condensate drain line is the second leading cause of AC failures.
Regular Maintenance is Essential
As part of regular spring/summer HVAC maintenance, the evaporator coil and condensation lines are cleaned. Having your system’s evaporator coil cleaned not only works to reduce smell, but the procedure will also improve the efficiency of your air conditioner. The mold, mildew, and dirt deposited on your coil will reduce airflow through the system, lowering its efficiency, and causing your HVAC to fail sooner.
Clean Condensate Pan & Drain Lines
But even if you’ve had your system cleaned at the beginning of the season, the condensate drain line could still become clogged during the course of use. So, it is important to check the condensate pan and drain lines monthly throughout the air conditioning season. Here’s how:
Find the condensate pan – usually a metal or hard plastic pan about 3 inches deep – sitting below the HVAC’s air handling unit. In some cases, you may need to remove a metal panel to access it. The condensate pan should be nearly dry. If it has significant rust all over, or is rusted out in sections, it must be replaced. Plus, signs of rust means there has been water backing up in the pan regularly, which is not a good sign.
If the condensate pan has standing water in it or if there is water on the floor nearby, there is a problem with the condensation drain lines. If your HVAC unit is in the attic, you might see water coming through the ceiling! If this is the case, turn the HVAC unit off at the electrical switch and at the thermostat. Using rags or a wet/dry vacuum, remove all the water from the drip pan and around the unit. Then clean the pan with a mild dish soap or 10% bleach solution.
The drip pan connects to the condensate drain line, which carries water out of the home. Locate where the drain line exits outside the house. Be sure there are no obstructions, that the drain line is not buried under dirt or landscaping, and that you can see whether it is dripping.
If no moisture is exiting outdoors even while the system is running or when the condensate pan is full of water, then the drain line is clogged. You may need to use a long, flexible rubber tube through the line – from each end – to dislodge the clog. Another option is to connect the wet/dry vac to the outlet, and use your hands to make a “seal” around the drain line in order to draw the clog out, or use an AC drain sucker kit.
With the system turned off, flush out the drain using distilled vinegar, hot water with mild dish soap, or a 10% bleach solution. Leave the solution to soak for up to 30 minutes, then rinse the lines with clean water. Be sure you can see the water exiting freely out of the exterior condensate line.
Special cases: If the drain line does not have a direct downward slope allowing it to make use of gravity to help the water exit, you may need to have a small pump added to help push the water out. If there is a reservoir which holds water until it exits, you may need to add a mild bleach solution, condensate drain line cleaner, or anti-algae tablets to the reservoir on a regular basis to prevent the growth of mold and algae.
If you care about the quality of the air you and your family breathes every day – and want to prolong your HVAC investment – be sure to get your HVAC serviced regularly, and keep that condensation pan and drain clear! If you’re not comfortable with any of the steps listed above, call on Interstate AC service at (615) 832-8500. Rest assured, we’re here to help!
We’ve been in the business almost 20 years now and have installed and serviced a variety of HVAC units. We are not paid by manufacturers to promote their brand(s); instead, we recommend brands based on our vast experience and our customer’s individual needs. If the customer has a preference for a certain brand, we do our best to provide it. But, if you really want to know which brand is best, here are the facts:
The Dirty Little Secret
When you look beyond the label slapped on the outside of the unit, you’ll see that most of the internal components are the same. There are about six HVAC equipment manufacturers in the U.S. who make about 150 different brand names. Many of them use the same internal components and are produced on the same assembly line in the same factory. Goodman and Amana are made in the same factory, yet Amana typically costs more. Carrier, Bryant, Payne, Tempstar, and Day and Night are made in the same factory, yet Carrier has more name recognition due to more advertising. York and Luxaire are both owned by Johnson Controls. There’s almost no difference between Trane and American Standard. Lennox, Ducane, and Concord are all made by Lennox. Even less obvious is that some of the internal components of all brands are made by just a handful of third-party companies, making many components interchangeable between brands. With so much the same, what’s the real differentiator?
The Real Differentiator
Unlike many other products, when you purchase an HVAC system, much of the design and engineering occurs on-site (at your home). Each home is different and presents different challenges with ductwork, physical location, clearances, etc. No brand, no matter how much it cost and its reputation, will perform reliably if not installed and maintained correctly.
The overwhelming majority of HVAC failures are the result of improper installation or maintenance. In fact, a good percentage of our business comes from people who hired the cheapest contractor to install their unit, or who think they saved money by not having regular spring and fall maintenance. There’s a proper way to install and maintain an HVAC unit and it’s worth paying for that expertise, because going with the lowest bid can often cost you later.
Just as not all doctors, mechanics, or hair stylists are the same, neither are all HVAC contractors. Sometimes, it’s worth going a bit out of your way, or waiting an extra day for an appointment to get a professional you trust.
Pitfalls to Watch For
Watch out for contractors who:
will offer you a great deal on a discontinued model,
do not provide continuing education for their technicians or use transient laborers,
don’t inspect your existing ductwork (if it’s a replacement) or will quote you a price over the phone,
won’t be around to honor the service agreement you purchased.
At Interstate AC Service, we use only qualified, licensed HVAC service technicians, we never use undocumented workers, we provide continuing education to our technicians, our technicians are not paid on commission, and we are committed to customer service.
Buyer Beware!
Don’t be fooled by a system that says it will last for 20 years. Not without regular maintenance it won’t! If you neglect your system, it won’t matter what brand you buy! Here are some other things to watch for:
Proprietary Design: With some brands, the parts may be proprietary and not interchangeable. So, there may be longer wait times for replacement parts because you can only get them from one manufacturer, and it may make the unit more expensive or difficult to maintain over time.
Specifications: When comparing units, be sure you’re comparing apples to apples. Comparing a SEER 14 unit to a SEER 21 unit is not valid, because each is built to different specifications and their cost to operate varies widely. Be aware that not all manufacturers offer units with the same SEER rating (Don’t know what a SEER is? Check out our post What’s Your SEER?).
Features: Look at the extras that may be rolled into the price. Is part of what you’re paying for the extended warranty? A bigger thermostat screen might not be worth paying extra for, but a quieter unit may be… only YOU can determine what features are of value to YOU.
Reviews: Few people will go online to write something positive about an air conditioner, heat pump, or furnace. It’s only when it doesn’t work that people typically feel compelled to write a review. Keep in mind when reading reviews, you cannot know reliably what the circumstances were. Most failures are not due to the workmanship inside the unit but to the faulty installation and maintenance. Did the installer install a mismatched AC condenser and evaporator? Was the unit maintained under a service contract the entire time? Take the reviews online with a grain of salt!
Allegiances: Use an impartial contractor – one that is licensed to install and service all major brands. A “factory-authorized dealer” for a single brand can only offer you the prices and features of that brand, even if that might not be best for your needs. Not having a vested interest in one particular brand means you’ll have more options. [Note: Interstate AC Service is licensed to install and service all major brands – both residential and commercial.]
Bottom Line
The most important aspect of your HVAC system is not the brand you choose, but the contractor! Except for minor differences, all brands are fairly comparable, but it’s the installation and service that matters. Unfortunately, buying a “top” brand (one you’ve heard of or has good reviews) doesn’t matter much when it comes to HVAC units.
If you live in the Nashville or surrounding area, and need help with an HVAC issue at your home or business, know you can call on Interstate AC service at (615) 832-8500. We’ll provide unbiased, professional service you can trust. We never forget we’re here for you!
When sizing up a new air conditioner, heat pump, or HVAC unit, it is common to hear the pros throw around terms involving tonnage, saying for example, you need a 3-ton or 4-ton unit. For reference, 4 tons is about the weight of an adult elephant! But don’t be alarmed: they’re not talking about the weight of the unit! This is a throw-back from the 1800’s and the term stuck. You may also hear pros refer to the capacity of HVAC units in terms of BTUs. Did you know these terms are related? Here’s how they originated:
Historical Perspective
Before the modern air conditioner was invented, people used to cool buildings in the summertime using ice harvested from rivers and lakes. Gathering the ice from farther and farther north and shipping it down south, or storing it from winter until summer, meant a lot of ice was lost to melting. A BTU, which stands for British Thermal Unit, is the amount of heat required to raise 1 pound of liquid water 1 degree. But, when water is below freezing (less than 32 degrees Fahrenheit), the amount of heat needed to melt ice is 143 BTUs per pound.
How the Math Works Out
A ton weighs 2,000 pounds, so to melt a ton of ice it takes (143 BTU/lb) x (2,000 lbs) = 286,000 BTUs. How quickly the ice will melt depends on how quickly you heat it. If you apply the heat uniformly over a 24 hour period, the ice will have absorbed (286,00 BTU) / (24 hours) = 11,917 BTUs per hour. That number is generally rounded up to 12,000 BTU/hr. So, a one ton air conditioning unit has the capacity to cool up to 12,000 BTU/hr.
Sizing an AC Unit for Your Home
When comparing costs of different HVAC units, be sure you are comparing similarly-sized units. Central air conditioning units frequently have the capacity coded into the model number: for example, model RDR36 would be a 36,000 BTU unit, or expressed in tonnage – with 12,000 BTUs being the heat needed to melt 1 ton of ice – the model RDR36 would be a 3-ton unit (= 36,000 / 12,000).
Multiple Factors Affect Sizing
If you have a 2100 sq.ft. home, a 2-ton heat pump will not be adequate; you’ll need maybe a 3.5 or 4 ton unit. Here’s where having a professional who can do a site visit helps. There are many things that contribute to sizing an HVAC system, other than the number of square feet you want to cool. Here are just a few:
How well the house is insulated and when it was built
The numbers and sizes of the windows and doors in the house
The color of the roof: darker ones absorb more heat
The height of the ceilings
The overall shape of the home: long narrow houses lose more heat (through walls) than a more square house of the same size.
The size of AC’s condenser, and whether it is positioned in the shade or in the sun
The efficiency of the cooling unit, often expressed as a SEER rating, or seasonal energy efficiency ratio (see our post What’s Your SEER?).
Moral of the Story
Knowing the number of BTUs that will be required to heat and cool your house effectively is not only important in choosing the right size furnace and air conditioning system, but it can also tell you whether your existing system may be too large or too small… yes, a system that is too large will not cool effectively, so bigger is not always better! (read our post Think Bigger is Better?) Now that you know that tonnage does not refer to the weight of the unit, and how to convert from tons to BTUs, you can more readily compare units. Proving yet again that knowledge is power!
If you live in the Nashville and surrounding area, and need some help figuring out the right BTUs and tons for your home, we’ll be happy to help. Plus, if you haven’t had your spring tune-up yet, now’s the best time! Call on us at 615-802-2665.
Harnessing solar energy does not mean you need photovoltaic panels on your roof and technological solutions. There are many ways to design passive solar into a home that will allow you to lower your heating and cooling costs year-round, and make your home more environmentally friendly.
What is Passive Solar?
Passive solar means using the building’s windows, walls, and floors to collect, store and distribute solar energy in the form of heat in the winter, and rejecting solar energy (heat) in the summer. It is called “passive” because it does not use mechanical means to distribute heat, but rather takes advantage of natural convection, radiation, and air flow.
Is it worth it?
If you’re adding energy-efficient features into an older home (built before 1993) that currently has little insulation, less energy-efficient windows, and non-EnergyStar appliances, you may be able to reduce heating and cooling costs by up to 50-60%. That savings will pay for itself year after year, and many of the passive solar design features also add aesthetically to the house and increase the house’s market value (see “Going Green Can Add Value to Your Home”).
10 Ways To Incoprporate Passive Solar
If you are not building a new home from scratch, you may not be able to take advantage of all of the suggestions below, but, the more you can do, the more you’ll save.
Use wide overhangs on your house to shield the house from the sun in summer. Western or eastern-facing windows are particularly vulnerable to overheating in summer, so these should be shaded using overhangs and large leaf-bearing shade trees that shed their leaves in the fall.
Have south-facing windows that have an unobstructed view of the sun (no big trees or tall buildings in the way). Keep these windows clean and keep the drapes, blinds, or shutters open during the cooler months while the sun is shining. In the warmer months, place a removable reflective film on these windows or keep the drapes, blinds or shutters closed to block the sun. Remember: if light can get in, so can radiant heat.
Capture and store the sun’s heat in thermal masses inside the house. This can be concrete, brick, stone, or tile which is used on walls or floors. The thermal mass absorbs heat from sunlight during the heating season, and absorbs heat from the air during cooling season. You can easily create a thermal mass by having a brick or stone fireplace which extends up the entire wall, or adding tile or decorative concrete flooring in the room containing the best sun exposure.
Take advantage of the “chimney effect” (natural convection). Since heat rises, install operable skylights (skylights that open) in the upper-most areas of the house, such as an upper floor or vaulted ceiling.
Use clerestory and transom windows or light tubes to let natural light in year-round, so you minimize the use of electric lights. Convert all lights in the house to LED bulbs, which radiate far less heat.
An open floor plan takes advantage of passive solar the best, as do open stairwells and atria.
Install EnergyStar-certified appliances and fans throughout the home, and energy-efficient double or triple glazed windows. Casement windows offer the best air flow.
Add insulation to your attic. This will help year-round (see our post “5 of the Best HVAC Investments You Can Make”).
Make your roof reflective with a light color paint, or by using reflective paint, shingles, or tiles. Roofs receive the majority of solar radiation delivered to a house, so a cool roof will dramatically cut air-conditioning bills.
Allow the landscape design to work in your favor. Use evergreen hedges and shrubs as windbreaks. Use deciduous trees (trees that drop their leaves in fall) near the house, to provide shade in summer and allow light in in winter.
The real joy comes in living in an energy-efficient, eco-friendly, passive solar house that is not only beautiful, but saves you money every single day.
If you live in the Nashville or surrounding area, Interstate AC Service can help with all your heating and cooling needs. Call on us at 615-802-2665. We’re here for you!
It’s no surprise that the demand for air-conditioners is highest in the summer, and the demand for furnaces is highest in the winter. If you have an old or failing HVAC system, it will likely go out when it is stressed the most – on the coldest or hottest day of the year – when the demand is greatest. Well, that’s when everyone else is calling for service, too! So you may find, no matter what HVAC company you call, they won’t be able to get to you right away. [If you’ve ever had the unfortunate experience of needing a tow truck after slipping on snowy/icy roads, you know what I mean!]
Be Pro-Active!
The best time to get a new furnace is in the spring and summer, and the best time to get a new air-conditioner is in the fall and winter. Of course, if you’re replacing an entire system – like a heat-pump that is used for both heat and air – then the best time is during the “in-between” seasons – spring and fall – when systems are less stressed and the HVAC companies are not overrun with service calls.
Benefits of Being Pro-Active
Being pro-active has many added benefits:
You may get off-season discounts or manufacturers’ rebates. Plus, you’ll have time to get a professional analysis done of your home, get 2 or 3 quotes, and do research on the companies. You won’t be in a “desperate” situation: like having no air conditioning on a day with 90+ degree temperatures and 90% humidity!
It’s less disruptive for the homeowner. You can schedule the install at a convenient time for you, and you won’t have to worry about being down (without heat or air) when it’s most needed! Face it: it’s much less of an “inconvenience” to be without heat or air (while your old system is being removed and your new system is being installed) when it’s not freezing cold or blazing hot out!
It gives you time to research the various kinds of systems, and the various features, to find the one best for you. When it’s 7 degrees out and you’ve been without heat for 12 hours, you’re not going to be in much of a “shopping” mood and may wind up getting whatever is readily available and can be installed quickly, rather than the best system to meet your needs.
Think Spring!
If you know your HVAC system won’t stand another winter or summer… don’t just let it slip your mind as we approach spring. That’s when you SHOULD be thinking: now’s the best time to replace it! Remember, the best time to buy a new system is before your existing system fails, and before the extreme hot or cold weather arrives.
If you need heating or air-conditioning service, no matter the season, call on Interstate AC Service at 615-802-2665. We’re here to provide all of Nashville and surrounding areas with professional , dependable HVAC system service and installation.
One of the common problems we encounter is a heat pump that has iced up. A heat pump in good condition should be able to operate in below freezing temperatures without icing over, so why does this happen?
Things to Eliminate
Here are some circumstances that cause icing which you may be able check, fix or eliminate:
Check to make sure the outdoor unit is not blocked by leaves or covered in any way. Some people mistakenly think that covering the outdoor unit helps protect it from bad weather in the winter, but this is dead wrong. It always needs proper airflow around it.
Check to make sure you do not have water dripping into the unit by a leaking or blocked gutter. As temperatures drop, that water will harden into ice and could cause the fan blades to cease up.
Check to make sure there is room for water to drain away from the unit… that it hasn’t sunken into the ground. If water pools around the unit, it will freeze as temperatures fall, and the ice will impede the operation of the unit.
Check to make sure that nothing is restricting airflow inside the house, such as dirty filters or blocked vents.
If you’ve eliminated these as possible sources of the problem, then it could be a mechanical or electrical problem inside the unit itself. First, let’s look at how a heat pump should work.
How Heat Pumps Work
The refrigerant inside the heat pump transfers heat back and forth as needed. Even in the winter, there is heat that can be extracted from the outside air to help heat the inside of your home. But to do so, the refrigerant needs to get very cold… much colder than the outside temperature. When coils get this cold, water vapor in the air will start to crystalize into ice around them. To prevent ice build-up, the heat pump will periodically go into a defrost mode. A valve switches so that the outdoor evaporator becomes the condenser. This allows the coils to get warm enough to melt any ice that may have formed. While in defrost cycle, the fan turns off so you won’t get cold air blowing on you, or a second-stage heater comes on to offset this cold air. After the outdoor unit reaches a certain temperature, or after a certain amount of time goes by, the valve switches back and the system returns to normal heating mode, reversing the evaporator and condenser. This cycling on and off happens transparently to the user while the heat pump is in use.
Reasons Heat Pumps Ice Up
Perhaps the most common reason heat pumps ice up, is that the reversing valve gets stuck. This prevents the heat pump from going into its defrost cycle and the ice on the outdoor coils continues to accumulate until it impedes the turning of the fan blades.
If the reversing valve is fine, it could be that something is wrong with the defrost timer, sensor, or control module, so that the defrost cycle is not completing or not happening often enough or not being triggered at all due to a faulty thermostat or sensor.
If the system is low on refrigerant or the outdoor fan motor dies, this could also cause the system to ice up.
Each of these reasons will likely necessitate a service call.
In the Meantime…
If you can visually see your outdoor unit has iced over, turn the unit off. If you are able to, turn on the emergency heat mode until help can arrive. Do not continue trying to run the unit “normally” as this will only cause more damage, and don’t wait too long before seeking help, as this may increase the extent of repairs that are necessary. Do not try to pick off the ice with a sharp object, as the coil and fins will damage very easily, and you may cause a refrigerant leak.
Prevention
As with most HVAC systems, problems with a heat pump can often be prevented with proper maintenance. Getting a fall maintenance check before the worst of the cold weather sets in, and getting a spring maintenance check before the heat of the summer, will help lessen the probability that you’ll find yourself all iced up!
If your HVAC system needs attention and you live in the Nashville area, call on Interstate AC Service at 615-802-2665. We’re here for you.
