Additionally, you should make sure the technician is using a Freon detector and not just going by what he or she thinks, says Alexander.
"Have the technician show that they have used a Freon detector and that detector has indicated a leak or soap bubbles and ask to see the leak with the soap bubbles," he says.
Another sign that your coil needs replacing says Alexander, is always having to add Freon to the air conditioner. When Freon leaks out of your air conditioning unit, it's a definite sign that your coil may need to be changed, he says.
Lubricating your system
Not having enough lubrication in your air conditioning unit is another reason it may not be working the way it should be.
Some experts say you may be able to add oil yourself, but you might need a professional depending on how modern the AC's motor is. Newer motors may have sealed ports so you aren't able to add oil. You'll need to check your owners guide to verify. If you do find ports, turn the AC's power completely off and add five drops of electric motor oil.
Experts say not to use all-purpose oil, since it's not designed to lubricate your AC's bearings for a long period of time.
According to Interstate, one in five people perform maintenance on their air conditioning system themselves, and if the system does lack proper lubricant it could raise your electricity use by 5 percent.
In addition, the company says maintenance on your AC system twice a year will maintain up to 95 percent of its original efficiency and the cost it takes to keep it running properly will be made back quickly through lower electricity bills.
And central air conditioning units should last about 15 years, says Interstate.