My ac unit is a coleman eletric in a 78 model mobile home what need to know is what i need to fix it the unit won't shut off so the evaporator is freezing i tried turning it off at thermostat but it win't turn off is it the thermostat

I would say the contactor is stuck shut on the A/C unit.

I would say the contactor is stuck shut on the A/C unit.
where is the contactor is it on outside unit or inside and what does it look like

The contactor is inside the outdoor unit and it is really not something that an inexperienced person would change. For one thing it could be a 24 volt coil or a 240 volt coil, it could have two sets of points that open or it could have one set of points that are made all of the time to operate the crank case heater.

Thank you so much i replaced the contactor for forty dollars and save money because i didn't have to call an ac tech thank you for your help

I don't know what kind of contactor you bought for $40 the average is around $20.

the one that was the same as what i had was 78 dollars and i even check the price in the internet and the price was the same 78 dollars plus shipping