We've taken this car to 3 different shops and can never get a straight answer. it's a '91 lebaron sedan and here is the problem: you push the button on the dash to turn on the ac, it lights up like it should, pop the hood look at the compressor, clutch is engaged, the two pressure lines are not cold, the drier isn't cold, and it blows hot air. I would assume if it were low on freon the low pressure switch would disengage the compressor. What do you think the problem might be?