There are two possibilities here. One, that the cooling system can't get you there. It's pretty unlikely but you should be able to tell because the compressor would be on all the time. It's a good idea to see what the duty cycle is anyway (if the compressor runs for 5 minutes and kicks in every 25 minutes you are at a 20% duty cycle). You really shouldn't be over 30% and probably closer to 20 or less (at 65° anyway).

The other possibility is that the thermostat doesn't go that low. If this is the case you have two options. Buy one that does go that low or take this one apart, figure out how it works and bias it lower. Of course you could always live with the temp you have.

Nate

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. '>