You need to make them comfortable at first, turn on the blower with them in the bathroom without drying them, just turn on the blower. Keep doing it for a couple of days to get them used to the sound, after doing that you can try drying them a bit, but if they freak out wait a couple more days, keep doing it until they get a little more used to it. then they should be less scared and there you can try to use the blower on them, they should be fine if you do that <3 (sorry if there are things you don't understand or misspelled, I'm not good at writing in English) ╥﹏╥
my dog HATES being bathed and dried. what i would suggest is you get a leash for cats, that way it stops them from moving. another thing is don't have the temperature so high on the blow dryer, and don't turn the air setting to the highest. if you're going to let them air dry, don't let them go outside and keep them in your house for the time being. if you know your cat likes to roll in mud, try to not let them out near muddy places, and only let them roll in mud the day you're going to shower them
Can I get some advice from all animal lovers out there I can never get my cats and dog to use a blower whenever I turn it on they run away. So instead I just let them get air dry but that clearly is never gonna work either since they just role in the dirt after they bathed every time(╯°Д °)╯╧╧