If you're just running the drill motors, their not gonna get hot because their is no load or strain on them. In competition, a lot of strain is put on the motors, and they get extremely hot. Using muffin fans is a very good way to keep them cool throughout the match.
As for using canned air to cool the motors, this is not recommended by a number of people, including engineers on this very forum. The reason is because it can damage the brush housings inside the motor. My team did this last year before each match, and while it worked well for a few matches, we started seeing problems down the line, such as the motors cutting in and out. It's just not recommended to use.
http://www.lions.odu.edu/~averma/pow...ill/sld005.htm
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