HVAC units remove heat, cold, and moisture from your house, but this process has an unfortunate by-product in the form of moisture build-up. There is a built-in mechanism designed to address this issue, but sometimes, it fails. When this happens, the unit leaks excessive water—flooding your house. Other problems, such as malfunctioning parts of the HVAC units, can cause moisture build-up as well.
Water Build-up on HVAC Units
While moisture build-up on the HVAC units is perfectly normal, it becomes a problem when it leaks into your house. To better understand this scenario, try pouring cold water into a glass on a hot day. Notice the moisture build-up on the exterior of the glass; eventually, it begins to drip down.
This condensation process happens in your standard AC unit. An AC unit contains an evaporator coil that houses the cold refrigerant. Warm air inside your room is blown over it, cooling the air and causing moisture to build-up on the coils. This moisture then drips into a drip pan and down a condensate drain line that leads out of your home. This process is contained inside the HVAC unit. If you see any water outside the unit, there is a problem. Listed are a few reasons why there may be water escaping from your HVAC unit.
Clogged Condensate Drain Line
A clogged drain line is the number one cause of water leaks from your AC unit. Accumulated dirt can easily find its way to the drain line with the help of water flow. When this happens, water backs up. Backed water causes further problems because it can create sludge and mold, clogging the line even more and will eventually fill up the drip pan—overflowing the unit.
There are numerous unclogging methods, but a guaranteed way is to have a professional use a vacuum to suck out the blockage material or opt for a drain line with an air vent and P-trap.
Old Damaged Drip Pan
Due to its long service duration, old drip pans can develop rust and holes, so water just falls right through. If this happens, you must replace it with a new drip pan. Maybe add it to your yearly maintenance routine.
Malfunctioning Condensate Pump
If your HVAC units are located in the basement, it needs a condensate pump to push the water outside your home. But if the pump is malfunctioning, there will be no means to push water outside and will eventually fill up the drip pan—overflowing the unit. Ensure that the condensate pump is functioning soundly.
Dirty Air Filter
Dirty air filters block the smooth airflow of warm air to the evaporator coils. Due to obstructions, an insufficient amount of warm air is blown over the evaporator coils causing it to get too cold and freeze over. The accumulated ice will eventually melt, and the drip pan may not be able to handle the excess water, causing it to overflow. Cleaning your air filter is an easy task, and you need to do it frequently to prevent dirt build-up.
Misaligned Unit Placement
AC units placed on an inclined surface may not allow condensation to drain properly. Instead, install the unit slightly inclined towards the condensate drain line to force the water into the drain line by gravity.
If your AC unit is not sealed completely, warm air can get inside the unit. Excess warm air constitutes excess moisture build-up due to condensation, which can overflow the drip pan. Ensure that your unit is correctly sealed.