If you live in the Southeastern United States during the hot summer, you undoubtedly are familiar with the humidity that comes with living here. But that sticky sweaty humid air can also wreak havoc on your air conditioning system. There are so many times I have received calls from frustrated customers who have tried everything to get their air conditioner to turn on. It can be frustrating and more than just irritating when you think you know the problem, attempt to solve it, and still, nothing improves. Throw on top of that the humidity and heat and you have the makings of a boiler about to explode.
The problem is twofold: the humidity and, in most cases, the use of cheap fiber air filters. Now I know most of you have your eyes wide open or are in total disbelief with that statement. Some of you will not even finish this article, but if you stick with me, I’ll explain why your thermostat just went blank and your air conditioner has shut down, and further why you should be concerned about water damage to your house. You see, that humidity in the air has just threatened your home and tens of thousands of dollars in potential repairs could happen at any moment. And your first thought to change the thermostat won’t help the situation.
Let’s start by explaining what an air conditioner does so that you can follow my thought process and realize that when I tell you to go look somewhere you will not be as shocked with what you see. So let’s get to the point, the main purpose of an air conditioner, like its name states, is to condition the air, not just cool it. Conditioning the air is making it comfortable for you to relax and enjoy the environment. That comfort zone is a range of temperature and humidity. At high temperatures and low humidity, you can feel just as comfortable as you would at low temperatures and high humidity. Typically this range is around 20-80% humidity at 68-82 degrees. Also, the air has the property that at higher temperatures it can hold more water. So 50% humidity at 90 degrees has more water in the air than 50% humidity at 70 degrees. That difference in water content is what the air conditioner must remove to make the indoor temperature comfortable.
So now you know the two things the air conditioner does, it cools the air and removes the water from the air. Now we are closer to the problem: where does all that water go? Most systems are designed with either a straight drain that uses gravity to carry the water away from the air conditioner and out of the house or a pump-type removal. Pump systems are usually not the problem unless the pump has failed. But the more serious problems are where there is no pump and straight drains are used. Where straight drains are used, and the drains have to travel horizontally, these drains are laid down in very shallow slopes of about 1 inch down per 8 feet horizontal (1% slope). That is not much of a slope but is enough to carry the water away if nothing blocks the path of the water. And that risk of blockage is what has caused your thermostat to go blank.
Now I get to the meaty part. Now it’s time to take a look at the air handler or evaporator coil is on the inside of the house. There should be a metal pan underneath the unit if the unit is in a closet or attic. This pan will probably be full of water. There also should be a float switch mounted to the pan that has been tripped. Your thermostat is connected to that float switch. It is a safety mechanism to shut the system down and stop it from collecting any more water. If it were allowed to continue to collect water the pan would overflow and the water would damage your home. Also, I don’t trust those pans 100% because they rust out or have bad seams from the installation which can leak and damage your home before the float switch is ever tripped.
But why did the water accumulate in the pan instead of going down the drain? Now it’s time to bring in those cheap air filters into the discussion. You see, the air carries dirt particles that cling to the moisture in the air. When the moisture is removed the dirt also is removed with it. The cheap air filters have too many porous holes that do not remove enough of the airborne particles of dirt to prevent them from collecting in the moisture that the air conditioner removes. This dirt then builds up in the drain lines and creates clogs in the p-trap or elbows or other joints on the low sloping condensate pipes creating mini dams that back up even more debris and eventually stop the water from draining out and away from the house. Then the water finds another escape route and ends up in the metal pan below your evaporator coil.
So you see, the problem isn’t your thermostat, the problem is water and cheap filters. There are several remedies on the market that will help prevent this from occurring in the future.