Found some help at Appliance Repair Forum, sharing the post here to help others with smiler problem. Appliance Repair Forum
What you need to do is determine if the gas and electrical are being activated at all when the unit calls for cooling. Start the unit and wait for it to reach the set temperature. Disconnect the thermistor so that the unit thinks the temp has risen and calls for cooling.
Check that there is (or isn't) power going to the heating element. If no power see below. If it goes to gas see if the gas ignites and if it stays lit or goes out. If it goes out and keeps trying to reignite replace the thermocouple. If it just keeps sparking let me know and we can go from there.
Basically it sounds like the unit is not resetting and calling for cooling after the initial cool down. This can be a thermistor but not very often. It is almost always a control board. If nothing happens after you disconnect the thermistor cut the 120 power and wait a bit. Turn it back on and see if you get power to the element. If you do the board is definitely bad. If still nothing at the element kill the 12 volt power and see if that resets it. If it does then again the board is toast.