Why is my AC not cooling?
Thermostat: Make sure the thermostat is set to cooling. Typically with the “mode” or “System” button you need to make sure you are set to cooling and not heating. The thermostat screen often displays which mode it is operating in. Info: some modern ‘stats have an “Auto” mode that automatically swaps between heat and cool. Make sure your cooling setpoint is below the indoor temperature. If you just made an adjustment, be patient, thermostats can have a 5 minute protection delay when they are turned off and on. Tip: a quick way to test if your thermostat is even working is to turn it to “FAN: ON” and make sure you can feel air blowing or hear the indoor fan running at the air handler.
Filters: A plugged filter can severely hamper to ability of an HVAC system to cool. One inch filters need to be replaced monthly in Florida, especially the pleated ones (which we do NOT recommend using) and even the ones claiming to last 3 months. Info: after a filter gets plugged to a certain point the dirt finds tiny gaps to bypass the filter and jam into the indoor coil requiring a professional cleaning.
Breakers: Air conditioning systems have 2 (two) double width breakers and both need to be on for your system to function. If the breaker is in the middle between on and off, turn it fully off first and then fully on. Make sure you reset both breakers. Tip: if your breaker continues to trip then call a professional HVAC company immediately.
Frozen Coil: If you see ice on the piping at the air handler or condenser you probably have a frozen coil. Common causes of a frozen coil are low refrigerant (a leak) or poor airflow across the indoor coil. After you make sure your filter is clean, You can attempt to thaw the coil. For a heat pump or gas furnace you can run the system in heat mode for 20 minutes or so while checking the pipes for ice, also water should start draining for the condensate line in a gush as the ice melts. The option for cooling only systems is to run the fan on only (system off) for hours until the ice melts. When you feel your system as thawed out, run in cooling as normal and check the piping occasionally for freezing. Info: this is likely a temporary fix and you should get service as soon as possible.
Plugged Drain Line: This is by far the most common reason a cooling system stops functioning suddenly. To see if this is your issue, get to your air handler and check for water in safety switch or the overflow pan. Doing this repair will require a wet vac. The first step is clear the water from switch reservoir or the emergency drain pan. These pans can hold several gallons of water and are in an attic or hanging high in the air, be careful! As soon as your safety switch is clear, the system will start running again, but you have only fixed the symptoms. The real problem is algae build up that has clogged your drain line. Next you must find your condensate drain outlet outside, This is typically a white pipe that empties onto the ground near your outdoor air conditioning unit. Connect your vacuum to this pipe and vacuum it for 5 or 10 minutes. You can use your hand or duct tape to get a tight seal to the pipe. Tip: If you vacuum this pipe monthly in the cooling season, you may prevent this pipe from clogging and shutting off your system.
Disclaimer: attempting any of these repairs could electrocuit, maim or outright kill you. Be sure and be confident before attempting. Your safest move is to call us for service, we keep these parts on our service trucks.
Capacitor: A capacitor stores energy until needed and releases it all at once. In the case of hvac systems a capacitor gives the motor in a fan or compressor the push it needs to start. If your outdoor unit buzzes or hums but the fan fails to move you may have a bad capacitor. If during this buzzing you push the fan blade (do NOT use your fingers) and it spins up to speed, you are on the right track, and that push may cause the unit to start cooling temporarily until the system cycles off and fails to start on the next attempt. The typical capacitor usually has 3 connections marked “R”, “C”, and “HERM” and must be installed exactly as the old one was. Warning: capacitors are what make tazers possible and can hold a deadly charge even with the power removed.
Contactors: Similar to a relay, a contactor functions as a high current carrying switch in which a low voltage/amperage control voltage can turn on a high voltage/amperage load. Contactors have large surface area contact points that are forced together when activated. Over time the arc when the points meet or unfortunately located tiny bugs will cause the points to burn or corrode and lead to a failure. Again, if you hear a buzz, a hum, or no noise at all at the outdoor unit when the system is on you may have a bad contactor. Before replacing a contactor make sure the breakers for both the indoor and outdoor units are off. Info: failure to turn off the indoor unit may cause the fuse or transformer in the indoor unit to fail leading to more repairs. I always recommend the one-wire-at-a-time method where you take a wire from the old part and put it on the new part one wire at a time until finished.
Tip: These two advanced fixes, along with the previous repairs are all issues at can be detected with regular maintenace appointments. These components may show signs, when inspected or measured, of impending failure.