What Could Go Wrong with My Air Conditioner?

When you walk through your front door after enjoying a hot summer day, air conditioning can feel like a miracle. But like most creature comforts in your home, your air conditioner is an earthbound machine that is vulnerable to all sorts of mechanical failures and damage. To keep that miraculous sensation of cool, comfortable air, you'll need to properly maintain your system and address any items on your air conditioner repair checklist.

You never know what misfortune might befall your air conditioner. In some parts of the country, homeowners even have to worry about "crazy ants" making their homes inside their AC compressors, shorting out circuits and nibbling on wiring. Fortunately, most AC problems aren't so crazy. Here are some of the most common air conditioning problems, along with HVAC troubleshooting tips to help you prevent them:

• Clogged filters. This is an easy maintenance task that most homeowners perform themselves: replacing the HVAC filter on schedule, usually monthly or every three months, depending on the type of filter. When filters aren't changed regularly, they fill up with dust and restrict airflow through the entire system. This can reduce system efficiency and airflow throughout your home, as well as accelerate wear and tear on system components. Always keep a supply of replacement filters at home, and set reminders so you won't forget to change them.
• Low refrigerant. Refrigerant is a chemical solution that absorbs heat from your home and allows it to be expelled outside. If your system is leaking refrigerant for any reason – age, poor maintenance, improper installation or physical damage – your AC will eventually struggle to keep up. The problem will only get worse until a licensed HVAC technician repairs the leak and replenishes the refrigerant supply. The best way to monitor for this problem is to schedule AC tuneup service every year, and to keep an eye out for moisture or oily substances around hose connections on your outdoor compressor.
• Blower problems. While your air conditioner is responsible for removing heat and supplying cool air, it's the blower that actually moves air around your house. The blower is a powerful fan system with many moving parts that require occasional lubrication, as well as a fan belt that must be periodically replaced. If the belt breaks or if bearings run dry and seize up, your whole cooling system will grind to a halt. Inspection, lubrication and necessary parts replacement are all usually part of your annual AC tuneup service, so as long as you keep up with the core maintenance, you're less likely to experience sudden blower issues.
• Failing capacitors. The small, largely hidden components that spark your compressor motor to life are called capacitors, and they have shorter lifespans than most other AC system parts. Every time your thermostat sends a signal to start cooling, it's the capacitor that provides the jolt that gets the cool air flowing. During your annual tuneup, your technician should replace any capacitors that show signs of wear. But if these parts are allowed to suddenly fail, the whole system goes down.
• Thermostat malfunction. The thermostat is the brain of any AC system, and when it malfunctions, all sorts of problems can arise. Your AC could run constantly or not at all, it could become unresponsive to user input or it could even start reading room temperature incorrectly. Your HVAC technician should inspect your thermostat as part of annual maintenance, but like any electronics, thermostats can sometimes fail without warning. When this happens, replacement is almost always a more cost-effective solution than repair, and it also provides the opportunity to upgrade to a modern smart thermostat.
• Clogged drain line. Air conditioners produce condensation as they operate, and this moisture drips into a drain pan before funneling into a drain line. Depending on where your system is installed, this drain line may lead to a basement floor drain or directly outside your home. If the line becomes clogged with dust, dirt or the formation of mold or algae, the water may back up and overflow the drain pan, creating a wet mess and potentially damaging system components. Your HVAC technician should inspect and clear this line as part of routine maintenance, but as an added preventative measure, you can occasionally pour a cup of white vinegar into the drain pan to inhibit mold growth.
• System failure due to age. Nothing lasts forever, and when it comes to air conditioners, most systems last between 15 and 20 years. As your system ages, it will gradually lose efficiency and may eventually start experiencing more mechanical breakdowns. Planning ahead for system replacement every 15 to 20 years can help you avoid an expensive yet unavoidable surprise. Proactive replacement also means you can schedule it outside of cooling season, so you're not sweltering at home while waiting on emergency repairs.

You can find more tips for taking care of your home in our Learning Center.