1 However, if you want to do the job yourself, the costs for the fan motor itself will usually be between $50 and $200. 2  For example, users on DSLReports.com said that a DIY job will cost around $75. 3  If the professionals are brought in, plan on spending around $300 to $500.he fan motor for your AC unit is an integral part of the air conditioning system. Without the fan motor, the fan would not spin. This means that the cold air produced by the air conditioning unit would not be propelled out of the unit and into the home or building.