An air conditioners primary job is to remove moisture from the room to give us a feeling of comfort. During this process they create a lot of water. How much, is dependent upon humidity in the air, size of the air conditioner, its operating efficiency, and whether it was properly installed.

Water removed from the air during operation falls down the cooling coil and drops into the base. From here it follows channels or passages to the rear of air conditioner. Some of the water is lifted up by the fan blade and used to cool the heating coil, while most proceeds to the rear. Once at the rear it drops out of the base and onto the ground. That is, if everything is working perfectly.

The reality of window air conditioners is that they can leak water. One that leaks can drive you crazy trying to find the cause of the problem. The following are a few suggestions of the most common reasons why water leakage occurs.

1. Improperly installed.

A window air conditioner must be slightly lower at the rear than the front. This allows the water being removed from the room to drain to the back of the machine. A difference of one inch is sufficient. This is always the first thing to check. Many are improperly installed in the haste to get relief from the heat. If installed too low at front the water will flow into the room rather than outside. If installed too low at rear, water can roll out front edges before has chance to exit towards rear drain.

2. Icing up.

Water being de-humidified can turn to ice if there are problems with the cooling system. There are many reasons for an air conditioner to produce ice. Remove front grille while machine is operating. If ice is present on the cooling coil you will probably need service. For more information see our other article: Why window Air Conditioners Ice up.

3. Air leakage around air conditioner.

If warm air is able to enter around the air conditioner it will encounter cooler, dryer air. When they meet condensation will occur. If water leaking from front of air conditioner inspect to see if dripping from body of machine, or water droplets clinging to front area. To test, operate machine for 30 minutes and then use flashlight to check under front edge of base. Small water droplets here indicate an air leakage problem. Add foam insulation to stop warm air from infiltrating.

4. Drain hole blocked.

Rear of air conditioner base has a drain hole or groove to allow water to escape. If becomes blocked water can back up. To test, operate machine for 30 minutes and then inspect if draining properly. If appears blocked use a small piece of wood to open drain hole at rear of metal base. CAUTION: Never be tempted to drill holes into the air conditioner body to relieve water pooling. Severe damage can result.

5. Internal drains blocked.

There are small passageways that allow water to drain from front of air conditioner to the rear. If they become blocked water will pool at front of machine and overflow onto floor. If this happens the air conditioner will require removal from window and servicing.

6. Outside temperature too cold. This occurs at end of cooling season. If outside temperatures drops below 60 degrees Fahrenheit at night the cooling coil may ice up. If no leakage at bedtime but water in front of machine in morning, suspect this problem. If this problem suspected turn off machine before bedtime and restart as day warms. Alternately, operate machine at night with selector switch in fan only position. This will circulate room air during night but not allow cooling.