Truck Smoking on 1998 Ford Ranger

when i try to use the heater or ac or defroster smoke comes out from under the hood, what is the problem & the estimaed cost

Asked by for the 1998 Ford Ranger
This type of problem needs a diagnosis before an estimate can be given. It depends on where the smoke is coming from. I think that the A/C compressor is seizing up, but have it checked out to be sure.