Why does my air conditioner run all day?
Most air conditioners are not sized for weeks of near one hundred degree weather. We size the condensing Units to find a perfect balance in the home for the Season. An oversized Unit will cool your home very quickly and not have the ability to de humidify and an under size Unit may not cool to the desired temperature but will draw humidity well. The air conditioner must meet the sensible and latent loads of the home (temperature and humidity) and the loads will vary during the hot months. Keeping the condensing Unit clean and replacing your filter are two ways you can be sure you’re not loosing capacity when you need it.
High indoor humidity can lead to health and comfort problems. Air conditioners dehumidify as they cool; you can see that by the water that drains away, but this dehumidification is incidental to their main job of controlling temperature. They do not independently control both temperature and humidity. Lennox Variable drives coupled with the correct thermostat will allow the system to chase its focus from sensible heat (temperature) to the latent heat load (temperature and humidity). Another reason systems may appear not to be producing enough cold air is because of duct leakage outside the building envelope. Duct leakage can sap 20 to 40% of the energy out of even a well-operating air conditioner, if the ducts pass outside the cooled space (this includes attics and crawlspaces) Ducts outside need to be well insulated. Sealing leaky ducts outside of your building envelope (the insulated part of the home) may be the biggest single thing you can do to improve efficiency.
If you are replacing the air conditioner, look to buy high efficiency equipment. The most generally known efficiency rating is Seasonal Energy Efficiency Rating (SEER). SEER 13 is the minimum efficiency you should consider, but higher efficiencies are likely to be quite cost effective. Depending on your climate, you may wish to consider other efficiency numbers as well. For example, in hot, dry climates you should look at the Energy Efficiency Rating (EER) which says how well the system will work at peak conditions. If you live in a hot, humid climate you need to consider how well the unit can dehumidify.
You can make your air conditioner work better by reducing the size of the job it has to do. You can do this by improving the building or reducing the internally generated loads that your air conditioner must deal with. Reducing internal loads can be simpler. Shut off unneeded electrical appliances, lights and equipment. Shift appliance use (such as washers and dryers) to cooler times of the day. Use local exhaust fans to remove heat and humidity from kitchens and baths. Buying Energy Star or similarly efficiency appliances helps as well.