Condensation

• Condensation is a byproduct of the normal operations of an air conditioner. A gaseous refrigerant is pressurized by the compressor (located outside) and sent to the evaporator (located inside) via copper pipes. Warm air from the house is blown across copper pipes (the coil) filled with the chilled refrigerant. The coil causes the air temperature to drop while the refrigerant is warmed and returns to the compressor. During this process the copper pipes of the coil create 5 to 20 gallons of condensation, which drips to the pan of the evaporator and then is drained via PVC pipes. This process serves to dehumidify the air in the home, making it more comfortable and feel cooler.
  
  

Primary Condensation Drain

• The primary condensation drain usually exits from the evaporator near the base of the compressor. This pipe will trickle water during normal operations. There is an upright, open pipe near where the pipe leaves the evaporator. This is an air vent and can be used when cleaning out the drain pipe.
  
  

Secondary Drain

• The secondary or "emergency" drain leaves the evaporator from a different side. The purpose of the secondary drain is to warn the homeowner of a problem with the system. The pipe usually terminates over a window or a doorway. Water spotted on the window indicates a problem with the AC unit.
  
  

Clogged Drains

• Condensation drains are breeding grounds for mold and algae. Drainage problems often can be attributed to excessive algae growth in the pipes. Remove blockages with a wet/dry vac attached firmly to the outdoor drain pipe. If more suction is needed, pour a quart of water down the drain air pipe located near the evaporator or have a helper place a hand on the open pipe to close the suction. A plumber's pipe snake can be equally effective, but may not be long enough to reach the problem
  
  

Other Problems

• If you notice a leak in your drainage system, shut down the AC unit and seek out the source. Examine the PVC drainage pipe and look for cracks or loose joints. PVC is easy to repair, so taking a pass at it yourself can save the cost of a professional. Other areas to examine include the drip pan (if the system has one) used to catch secondary drainage. This pan can, at times, overflow. A simple float valve shut off can prevent an overflow. At times, the problem is built into the system, as shoddy construction practices often leave the secondary drain open to the floor. Rerouting the piping to join the primary drain can save costly ceiling damage.
  
  

Preventive Maintenance

• To insure that no algae or mold can grow in the PVC drains, each month pour a cup of bleach into the pipes from the drain air vent pipe. Be sure the bleach is put only in the PVC pipes. After 20 minutes follow with a gallon of water to push out any bleach residue that might corrode the PVC pipe if left standing.