Just bought a 97 Taurus GL used a few months back, and have only recently noticed that when the climate control is set to anything but "vent" I get a slight surge (+/- 50-100rpm) every 10-20 seconds. It's not a huge inconvenience, but I'm concerned that it's indicative of a bigger problem...

Am I being paranoid?

it could be normal however disconnect the battery for 15 minutes this will power down the pcm.then connect and start vehicle with no accessories on run for 5 minutes and shut for a minute. restart yet again after about a minute try the ac and see if improved.