Hey Boman,
Nate has a good idea. Check the thermostat. You can do this by simply putting the probe in a glass of ice water. Turn the knob and see if the stat clicks. Second, it could be as simple as cleaning the condenser coil. One more thing, also see if your fan motors seem to be turning at speed. If you not moving air across the coils, evaporator or condenser, your effiency will suffer.
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