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How to Kill Slime in an Air Conditioner

Owen E. Richason IV

Air conditioners work by compressing a gas coolant into a liquid that goes through several coils. Fans push air over the coils, which produces cold air. Another component of an air conditioner is the evaporator, which produces condensation. This condensation is caught in a drip pan. Because the condensation becomes largely stagnate water, slime begins to collect in the drip pan. Instead of contacting a service tech, you can kill the slime yourself.

  1. Turn off the air conditioner and switch off the breaker powering the unit at the main electrical panel.

  2. Go to your air conditioning system in the attic or in a small closet. Look for the external drip pan -- it will have water inside it. If you do not see a drip pan, open the access panel on the unit with a screwdriver to expose the drip pan.

  3. Put on rubber gloves. Carefully pull the drip pan out of the unit, if equipped with a removable drip pan, and dump the water out. If the drip pan is not removable, scoop the water out with a plastic cup.

  4. Spray the evaporator coils liberally with an aerosol evaporator coil cleaner, then spray in and around the pan as well.

  5. Thoroughly wipe the evaporator and the drip pan with a soft sponge to get the slime off the unit. Wipe away as much slime as possible, then reinsert the drip pan, if applicable.

  6. Place two condensate pan tablets in the drip pan and allow to dissolve. The tablets will release an ingredient that prevents slime from forming.

  7. Close the access door or fasten it back into place with a screwdriver. Turn the breaker on, then the air conditioner.