[Woodyboat]

Sorry for the double post... but I got to thinking about this.

I've seen a lot of people block off their rear AC units because the extra complications make them seem intimidating. THEY'RE NOT! Rear AC units are very straight forward, stupid simple and there is no reason why they can't be made to work just fine ... adding a level of luxury that you'll soon begin to feel is NOT simply a luxury.

Like all Chevy/GM vehicles of the era, your stock system will have an accumulator that mounts to the firewall and an orifice tube somewhere very near in the intake side of the accumulator. You can find it because you will see a connection close to the accumulator that will have a couple of pinch marks in the line to keep the orifice tube from sliding too far down the line. Find the pinch marks and you can find the orifice tube.

The rear AC unit will have a Thermal Expansion Valve (TXV) instead of an orifice tube. Be sure to replace this when/if you get the entire unit out of a donor vehicle and of course, you'll also want to flush everything possible. There will be a capillary tube on the TXV that has a bulb on the end that gets fastened up against one the lines of the evaporator. This is important so that your TXV knows how to regulate the refrigerant. I always use a little hose clamp to fasten the bulb on the proper line to make sure that the connection is good. You'll see what I mean when you get into it.

Here is another little snippet of knowledge that not just anyone knows. Vehicles with front and rear AC have extra fan controls on the dash for the rear fan. So you'll need to fab a mount for the rear fan control knob. The fan motor on the rear of my Vandura is exactly the same fan motor as the front. YAY GM. But here's the important part. Whenever you run the AC, always turn the rear fan on as high as it will go. This is because the distance the refrigerant has to travel from the rear of the vehicle back to the compressor is enough that it can possibly turn from gas back to liquid. The compressor will NOT want to be pumping noncompressible liquids. Keeping the rear fan on high will help to keep it gaseous. Your compressor will thank you and I know your kids will too.