My ac will not automatically shut off. It also takes about 3 hours for the temp to drop one degree. I replaced tstat and still have the same problem. I ran the heat which of course is on the same system, it it works fine, heats up and shuts down as it is suppose to. I have had 3 service calls on this and they can't find anything wrong. Help me.

It may not be cold enough to shut down(Poor insulation?)
Does outside unit unit blow out warm air, and is air handler producing water, if so, it is cooling?
If you raise the temperature, will it shut down? may be a delay, wait a minute or 2.

Thanks for such a quick replay. The unit has run fine for 9 years without event. I bought a mercury thermometer so I could compare actual air temp to actual air temp on tstat. Tstat just will not drop temp. There is about a 5 degree difference between the thermometer and tstat. I recalibrated tstat to match actual air temp. Still won't shut off. To answer your questions, the unit does blow warm air and is producing water. It seems to work just fine. Yes, if I raise the temp it will shut down. That is the only way it will. Will not respond to the auto setting.