Our central air conditioner would not start. Since we had this covered under our utility provider's WorryFree Services program, they sent a technician to look into the problem. The technician had to replace something like a transformer which had died due to old age. The airconditioner runs now except that the auto shut-off will not kick in when desired temperature we set is arrived at. It just keeps running and running. Is this something the technician might have done or is this a thermostat problem? We reset the thermostat already. We shut it off when the house was very cold and turned it on again and set it to "auto". When the temperature inside the house finally went up, the A/C automatically started running again. However, when the desired temperature was achieved, the A/C won't shut off. It just keeps on cooling the house and temperature just keeps on getting lower.

If this is a programmable thermostat then I would say that you will have to reprogram the thermostat , the service person probably programed it to run at a lower temperature to check it out and then did not change it back to what it was before.

I would advise calling the technician back, just to check things over. It could be a crossed wire or something. Are you familiar on how to operate the thermostat? Is it programmable?

Thank you for your responses. I called the technician back (the utility company actually sent another technician.) From what I understand the first technician did some wiring wrong. Something like shorting the thermostat. Anyway, the thermostat was replaced with a new one, they (the 2nd technician had to call for another technician) spent a lot of time fixing some wiring and now it works properly. Have a great day, you all!