According to the U.S. Department of Energy, air conditioners need regular maintenance to work effectively; avoiding that maintenance leads to higher energy consumption while your AC's performance goes downhill. HVAC experts agree that it's generally best to get your AC tuned-up once a year, preferably during spring before the summer heat arrives.
If you've been putting off your AC's annual maintenance appointment for the past few years, you'll likely see the following problems emerge.
Are there warm spots in particular rooms or areas of your home after the AC shuts off? Dirt and debris may be clogging the vents to those rooms. Another possibility is that the ducts leading there have leaks. Both issues could have been identified early on with annual maintenance.
You may have a bad compressor or low refrigerant levels if the conditioned air blowing out of your vents is lukewarm. However, more often than not, severe dust buildup is the real culprit behind lukewarm air. When dust accumulates on your AC's evaporator coil, the refrigerant in the coils is unable to absorb the heat from the warm air that's blowing across it. The condenser, located outside and responsible for cooling refrigerant before it returns to the outdoor unit to absorb more heat, might be faulty or caked in dust as well.
Abnormally Loud Noises
It's normal for an AC to make some noise when switching on and off, but if a sound is unusually loud and continuous, then you likely have something that could have been avoided with a tune-up. For example, loose components will rattle or bang, defective relays will click, and a bad motor or motor bearing will squeal. Leaking refrigerant can cause a hissing or whistling noise. Loose electrical connections will buzz.
Have you noticed a burning smell or a musty odor from your AC? The former would likely be due to the bearings overheating from lack of lubrication. Mold or mildew growth causes a musty smell. Mold growth often occurs when a clogged condensate drain line allows condensation to collect in your AC's drain pan.
A Spike in Energy Costs
Together with weak or uneven cooling, you’ll probably see a jump in your utility bills. This is to be expected since the various issues plaguing the AC are forcing it to work harder to achieve your set temperature.