The average lifespan of a central air conditioning unit and its components is between 15 and 20 years, but an air conditioner's lifespan can be affected by installation, usage and general maintenance factors, notes SaveEnergy123.com. Air compressor and fan relay controls can sometimes prematurely wear out due to high usage, oversized systems or inadequate maintenance.
The air conditioner fan relay operates the unit's motor when it turns on and off. A replacement fan relay may range in cost from $175 to $250 as of 2015 depending on the model and installation costs, states FastACService.com.
There are many reasons why an air conditioner compressor fails. Before replacing the fan relay or other components, make certain the condenser is clean and has proper refrigerant levels.