Replacing an air compressor governor is typically a job that requires the expertise of an air compressor repair service. Generally, the average hourly cost for this service is around $50 - $100, depending on the complexity of the job and the type and quality of the accessory. The cost breakdown usually includes the price of the part, labor, and any other materials that may be necessary for the repair. It is important to note that factors such as the type and quality of the accessory, the complexity of the job, the location, and the service provider can all affect the cost of the repair. For example, if the air compressor governor is of a higher quality, the cost of the repair may be higher. Additionally, if the job is complex and requires more labor and materials, the cost may be higher than usual. Finally, the location and service provider can also affect the cost, as some service providers may charge more than others.