Mercedes Benz 1995 C220 Air Conditioner

My car air conditioner blows cold air out the passenger side and hot air out the drivers side. Regardless of what setting I use the right side gets cold air while the left side gets hot air. I sense its a flow valve somewhere that's malfunctioning, but should be easy enough to fix since everything else regarding the air conditioner is fine. However, I have been told that the only way to solve the problem is to dismantel the whole dashboard. As you know this is very labour intensive and could cost $1,000.00.'s

Is there a short cut possibly, through a process of elimination, to get to the root of the problem?