98 beetle hvac

does anyone have advise ? my daughters 98 beetle, air won't switch to floor or defrost , knob won't turn all the way to defrost position . it looks like i have to take out the radio to check out the cables, there is foam coming out of the vents, maybe some foam lodged in a blend door somewhere ?also this past winter heater didn't work . how hard to get to the heater control doors ?
steve