Would wetting outdoor cooling fins improve the efficiency of an AC unit?

The unit in question is a central AC unit, but presumably the principle would remain the same for window units.

AC cooling fins aid in heat exchange by exploiting their large surface area. Would wetting the fins to take advantage of the cooling effect of evaporating water improve the heat exchange efficiency?

Yes, but it can drive down the suction and head pressure to the point the evaporator coil could freeze. Constant spray of water will corrode and calcify coil ruining the air conditioner before it's time. Are you on a well, or municipal water? Either way I wouldn't recommend this practice, ofter all if it was a good idea some one would have marketed it and sold it by now.

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Originally Posted by NorthernHeat

Yes, but it can drive down the suction and head pressure to the point the evaporator coil could freeze. Constant spray of water will corrode and calcify coil ruining the air conditioner before it's time. Are you on a well, or municipal water? Either way I wouldn't recommend this practice, ofter all if it was a good idea some one would have marketed it and sold it by now.

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Municipal water. I, too, figured that if it was a good idea, it would already be common practice. I'm no AC expert, but I don't understand how spraying water on the coils would drive down suction and head pressure in a closed system.

The lower the temperature the lower the pressure. Get a temp-pressure chart for refrigerant and you will see what we mean.

Wetting the condenser coil will assist in heat transfer but will cause corrosion, another option would be to add a precooler to your condenser, they do not put water onto the condenser coil, they work similar to a swamp cooler and are advertised to drop the temperatures by up to 15 degrees, depending on humidity and air flow.Master Cool is one manufacture who makes this item. Mike

By the way, window a/c's (most) have a slinger ring on the outside edge of the condenser fan blade to sling or throw the condensate into the condenser coil. Some even have a thermostaticly operated drain plug in the condenser section to hold water during the summer and opens during the winter for heat pump operation. Mike

Northernheat is right the cons out way the pros. Running water over the system will drop the pressures causing the evaporator coil to frost, after that it's the snow ball effect, the coil will ice up the amps go up on the compressor and the cool air has changed to no air. The slinger type window A/C that Acetc is talking about is so you don't have to run a condensate drain and it has a discharge line from the compressor in the drain pan also to help with evaporation. The water splashed on the condenser coil is a small amount at a time. Unlike what your talking about by spraying your coil. Northern I tried to give the credit but they said I had to share the love.

Thanks to all for the explanations; it indeed appears that my "little learning is a dangerous thing".