I recently had 5.3 LS swapped into my 1985 El Camino. Had new AC compressor installed also. AC blows cold but only through the defrost vents. I found that the vacuum is not connected at the firewall under the hood. Can anyone tell me where and how to get the vacuum connected to get the blend doors to operate. I also noticed that the heater control valve probably should have vacuum to it also, correct? Thanks in advance.