Are Your Coils Clean??
Can your heating and cooling breath like it's supposed too? It will if you change your filters regularly. Do YOU?
When I'm doing a Frankfort, Kentucky Home Inspection, I can't always get to the coils to see them, but I can almost always get my camera into the blower fan compartment to see what conditions are inside the unit. The blades should be fairly clean. When I can see the coils they should also look clean, kind of like the fins on your car's radiator.
Obviously, someone wasn't changing their filters on this unit.
This system isn't breathing very well. Though a little heat leaked through.
Dirty blower fan
Coils mostly blocked with crud.
The blower fan blades are covered with crud, reducing the energy efficiency. The coil is mostly blocked with crud, mud, pet hair and whatever other components make up this crud.
It's possible to restore the systems energy efficiency by having an HVAC technician remove the fan and coils, clean them, and replace them. BUT, it's likely to cost $400.00 to $500.00 to have this done.
My usual diagnosis:
The main blower fan blades are dirty which impedes the operating efficiency of the unit. This has also usually allowed dust to come in contact with the wet air conditioning coils. Wet plus dust equals mud on the coils equals coils being partially blocked. I can't see the coils to verify this though. I recommend that you have the heating and cooling unit serviced and cleaned (to include removal and cleaning of both the fan and the coils) by a qualified heating and air conditioning contractor.
Changing your filters on a regular basis is much easier and less expensive from both repair cost and energy cost standpoints.