Carrier/rack problems of the 2010 Nissan Versa

Check engine light came on and turns out the evaporator had a crack in it so paid Nissan $1,500 to replace it with a non-genuine evaporator part. Then about six months later the check engine light came on with had ac at speed 4 when driving at any speed. Told the blower motor was bad and needed replacing at the cost of $1,500 to do it. Refused the work and ran blower motor on a/c at speed 3 for about a month then after that seemed to work at speed 4 as well with no check engine light coming on. I thought it was probably the speed rheostat like happened to me on a Ford I had cost of item $25 and did it myself. The rheostat must have been stuck and become unstuck and I would have paid for a repair that was not needed and been scammed.