Carrier air conditiones 1978

I am not sure what else to do .Our air conditiones has being replased with new part since we bouht the house 5 years ago. last week january 2005 we woke up with smoke inside the house at 5:30 am and a very strong smell. Our carrier air central air conditioner was doing this.We turned off at the thermostat but never went off after a few seconds.We had to turn it off from the fuse box. We had to open all the windows while the temp. outside was in the 30's our daugher's rooms was the most affected and she went to sleep out in her car.We called a person that it was recommended and he found few parts that were dark also a metal filter with a lot of stuff he cleaned and check all the parts.after only one day the smoke came back again.The thermostat did not wanted to turn off again.The tec said he never had this problem before.The problem is that when he is here nothing happens.Is always early in the morning like this morning at 3:30am.HELP