Ah, the sweet relief of a cool, dry house after a hot, sweaty afternoon of yard work. Like any mechanical system, AC needs a little TLC to run smoothly, including many tasks you can tackle on your own. We asked This Old House plumbing and heating expert Richard Trethewey to share his know-how for central air and window units. Why and How to Change Filters Dirty filters kill your AC's efficiency, so install a new one every month during the cooling season for central and window units (or clean them if you've got the washable type). Look for the filter's minimum efficiency reporting value, or MERV, which ranges from 1 to 12 for home AC units; the higher the number, the better filtration it provides (and the more energy needed to pull air through it, so balance air-quality concerns with energy costs). Why and How to Fix Leaks Ducts can lose up to 30 percent of airflow through leaks, and window AC units are notoriously tough to seal properly. Find leaks using the old "smoke trick": For window units, light a stick of incense and hold it where the unit and the window frame meet;

for central AC, hold the stick near duct connections. If the smoke blows around, you've got leakage. For ductwork, use foil tape to seal small gaps and duct mastic for larger ones; how to tell what size my ac unit isfor window AC units, stuff foam betweeninside ac unit will not turn on the device and the window frame, taping as needed.how to tell the size of my ac unit Why and How to Use a Timer There's no need to blast the AC at full tilt while you're at work. For central units, install a programmable thermostat that lets you set higher temps when you're gone and cooler temps when you're home. Newer window units have built-in timers and adjustable thermostats, or you can buy a timer at any home store for $10 to $20;

just make sure it matches your device's voltage. Unless you're going on vacation, don't shut off the system; otherwise, the air compressor will need to work harder to cool your house later. Ducts in hot attics or crawl spaces should be wrapped to keep the air within them cool. You can use spray foam, batt insulation, or rigid-foam insulation. Seal batt and rigid insulation with foil tape (not duct tape). For tight spaces, wraps like Reflectix offer some degree of insulation. Why and How to Service Compressor/Condenser A central AC system's air compressor and condenser are usually located outside the house, close to your foundation. It works best when there's about 24 inches of clear space in all directions, so get rid of nearby shrubs, tall grass, leaves, and hanging branches. TOH Tip"Install condensers or window units on the north or east side of your house, or build a screen to shield them from the sun. Putting them in direct sunlight reduces their efficiency by as much as 10 percent."

—Richard Trethewey, TOH Plumbing and Heating Expert Why and How to Keep Unit Cool Extend the life of your AC system by keeping blinds or shades down during the day; you can also install awnings to shield south-facing windows from intense sun. Consider running the AC in conjunction with floor or ceiling fans to circulate cooled air more effectively. Why and How to Maintain Unit The dealer who installed your central AC (or one you find locally) should put you on a yearly cleaning schedule that goes beyond just cleaning the filters. Schedule this checkup before the cooling season starts (or do it now if you didn't do it earlier this year), and make sure it includes the following tasks: cleaning and inspecting coils; cleaning or replacing filters; adjusting and replacing fan belts; lubricating motors and bearings; cleaning and checking blowers and fans; inspecting controls and safeties; checking refrigerant and pressures; and verifying operating temperatures. Why and How to Get Airflow

Shutting too many interior doors causes central AC systems to go out of balance, meaning there's less airflow in the entire house. If you want some privacy, keep doors slightly ajar instead. Why and How to Upgrade Federal laws require AC units to be a lot more efficient than they were just 10 years ago. For central AC, look for the seasonal energy-efficiency ratio, or SEER; for window units, the measure is simply called the energy-efficiency ratio, or EER. The standards mandate a SEER of 13 and an EER of 8, but devices with higher numbers will cost less to operate.Welcome to the Comfort Zone Blog Ways to Help Prevent Frozen Air Conditioners Avoid Air Conditioner Meltdown There is nothing better than entering a nice cool house on a hot summer day. And few things are worse than sweltering in the heat as you wait for the HVAC technician to come fix your broken air conditioner, knowing it is going to cost hundreds of dollars to repair. The most common reason for a sudden air conditioner meltdown is frozen pipes and tubes.

Why do Air Conditioners Freeze There are lots of things that can cause your AC unit to freeze. A qualified AC professional can help you find the source of the problem, but it does not hurt to understand how freezing occurs so you can take steps to prevent it. Refrigerant Charge: If your AC is running low on refrigerant or the fluid is improperly charged, the system can freeze. Leaks are a common cause of refrigerant problems; these can occur when moving parts rub together or vibrate over time. Leaks are also likely to be found where fittings and shoulder joints are loose. Only a certified HVAC technician should check refrigerant levels and recharge the system if necessary. Airflow: Restricted airflow can cause the evaporative coils to get so dirty that they drop to a temperature below freezing. Humidity in the surrounding air then collects and freezes around the coils. If your air filters have not been changed in more than three months, airflow can be significantly reduced;

undersized ducts are another common cause of poor airflow. Outdoor Temperature: Running your air conditioner on cool days can cause the unit to freeze up. Most central AC systems are not designed to work properly when outside temperatures dip below 60ºF. How to Prevent Freezing Now that you understand the most common causes of air conditioner freezing, you can take positive steps to prevent problems in the future. Refrigerant Charge: To keep fluid levels functional, contact a qualified professional to perform a thorough test on your system. A technician will be able to look for leaks, repair damaged or weakened parts, refill coolant and make sure you AC is in good working condition. It is always a good idea to schedule maintenance before peak season to avoid high prices or emergency service charges. Airflow: Change the air filters regularly, usually about every three months or so. This is the simplest, most cost-effective way to ensure your air conditioner does not freeze.

If you notice that the AC’s evaporative coils are already dirty, you will need to have them cleaned by a professional. You may be able to vacuum out some of the debris yourself, but some have coils that need to be removed for proper cleaning. Outdoor Temperature: This one is pretty simple; just do not use your air conditioner when the outside temperature is below 60º. Not only will you prevent your system from freezing, but you will also save energy and money on utility costs by just opening the windows on cool days. So, when you are ready to install or replace your home’s air conditioner or heater system, please contact Horizon Services. Our friendly and experienced team of Home Comfort Consultants knows air conditioning and heating systems inside and out. They’ll take the time to study your home, understand your cooling and heating requirements, show you all of your options and assist you with finding the quality home comfort system that best meets your family’s needs and budget.