Air conditioners both cool and dehumidify the air, according to About Home Repair. Cooler air is unable to hold as much moisture as warmer air, making dehumidifying a natural part of the cooling process.
The first air conditioner was designed primarily to dehumidify. In the early 20th century, the Sackett-Wilhelms Lithographing and Publishing Company was looking for a solution to its humidity problem. Paper absorbed moisture from the air in the humid summer months, making it difficult to print properly. Willis Haviland Carrier solved the company's problem by creating an air conditioner to cool the air by blowing it over cold pipes. As the air cooled, it also became less humid.