Rough shifting and a strange feeling of brakes being applied with fan on

I purchased a 2000 Ford Escort ZX2 automatic 4 cylinder over the summer. The car runs great and shifts fine when all fans are off - air/heat/defogger. When a fan is on (and it does not matter whether it is on low or high or anywhere in between) the car does not run as well. The shifting seems much rougher and when I am on the highway, it almost feels as if the brakes are being periodically applied, when they are not. Anybody have any suggestions?

It may NOT be the fan that’s causing the problem. On many cars when you turn on the defogger it automatically turns on the AC. The AC may be the culprit. It can put a strain on a car…especially if there’s a problem.