After pulling the inner HVAC box and pulling apart everything to find out what's what, it was time to start making the modifications. Really the modifications aren't mods, but more simplifications of the overall system. Looking at the blend doors I found the one door that opens air to the chest level vents is a two piece door that will further regulate air flow between the chest level vent and the passage that would've moved air to the floor vents. Only thing is, I don't want to regulate air between these two vents, I want to regulate it, or more accurately, blend it, between the defrost and the chest level vents. To do this I closed the top half of the chest level blend door and opened the lower portion. Closing the top portion of the vent will allow air pressure to build up within the small area just past the heater core and only let a small amount move through the open bottom vent. The lower portion closes against the heater core, only leaving an opening above it for a regulated amount of air to pass over that opening and into the channel that would feed the floor vent and defrost. To hold the top portion of the vent in the closed position, I drilled a small hole in an extension of plastic on the outside of the box in order to place a screw that would hold the linkage for the top half of the blend door closed. Doing this will allow the new placement of the blend doors to do what I intended them to do while not rendering the HVAC box unable to be reverted back to the original state, if I, or a successor of ownership, so desires. Lower blend door linkage pinned in the open position with a single screw on a flap of plastic, as seen to the right in the picture. Also note the screw holding the top half blend door in the closed position via a hole drilled through the blend door edge to use an existing hole in the box to place the screw through. Now its time to go off on a tangent. The only original blend door control that we will be keeping is the door that regulates air movement between the AC and heat. Unlike the other blend doors, this is the only one that uses a cable to control the door's movement. The cable is connected to a lever on the control panel that allows for fine tuning of the position of the blend door to regulate the amount of hot and cold mixing in the HVAC box. The next order of business is the blend door that regulates air movement for the floor vent and defroster. This was a pretty simple setup, just positioning the blend door in the closed position for the floor vent, leaving the defrost vent wide open. Don't forget the intermediate area just after the heater core allows for a lesser amount of air to pass over and into the defrost area. This pin up was a little more invasive with me drilling a hole in a lobe of plastic inside the air plenum, and mating with an already cut hole on the edge of the blend door. A sheet metal screw allowed for the blend door to be secured to the lobe of plastic, in the closed position. With all the blend doors addressed, I had to address the large holes that were left open after removing the vacuum actuators. This was done in a way to be reversible, for already stated reasons. I did this little patch as neatly as possible, cutting a piece of sheet metal that fit inside the cavity where the actuators sat. Two holes were drilled and filled with two screws capped with nuts, holding the whole works in place. The same thing was done for the hole from a single actuator in the plastic box. Using the already made holes from the actuator bolts, the whole patch was done in a completely neat and reversible manner. After making these little modifications, I was able to reassemble everything and get the inner HVAC box mounted back in place on the inside of the firewall. With both HVAC boxes secured back in their respective places, I was able to remount the fender shield and put a close on this part of the project. Of course to fully complete the HVAC retrofit, I will have to get the blower motor and a power line for a future AC compressor clutch wired in so the control panel can do its job of controlling those critical components of the HVAC system fully operational. Of course in order to do that I will have to take on the rewiring of the car, getting those lines properly wired. Of course I will have to fully figure out the layout of the wiring for the resistor pack as well as the switch for the blower motor. I'm sure the interwebs will have schematics showing what the different colored wires represent on the whole set up.
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May 2023
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