I forgot to add one more thought - since the VCM stayed in place once the AC was running through the top vents, and only went into heat mode (up) when I turned the switch knob, it tells me that the VCM is not broken, i.e. it is not leaking air, and therefore should not need to be replaced. The only problem is that when you switch the knob back to AC, it does not move down, which is more than likely either the vacuum leak, or a faulty switch. Since I replaced the switch already, I am thinking vacuum leak. And if my thought is correct, than is it a leak on that white line only going from the switch to the VCM, or could it be that there is a leak elsewhere in the system, and it is affecting both the rear and front HVAC performance? I don't know the answer to that, and have no idea how to check for that. | 
