I've pulled a few fan motors out of cars and pickups.(I couldn't afford a shop at the time, so I had to develop shade tree mechanic skills.) Some were easy. Others took almost a day, since the entire dashboard had to be removed. The cost of the fan motor seems a little steep, but the factory guarantee will get the mechanic reimbursement if the motor fails before the warranty expires.

Demand the old parts when you go get the car. If they conveniently don't have them, you should have recourse to recover your money in small claims court. After all, they may have only had to change a 50 cent fuse and repair a nick in a wire. If they do have it, you can always take it to another mechanic and have it tested. Most fan motors give a little advance notice, such as a squeak or squeal. Since they are not servicable and can't be rebuilt, when they start acting up, the only option is replacement.