Whew! Ok, I knew this wasn’t going to be simple, but I learned some things about AC vs. non-AC cars. And my AC controller no longer taunts me: it said “AIR CONDITIONING” … obviously I know I don’t have AC! 😉 And my leaky vacuum switches and hoses are no longer an issue. (Huge props to you folks that keep those vacuum hoses and switches functioning!)
I want to start out by saying I wish I had functioning factory AC, but the system didn’t work and was missing too much to try to revive. I know removing the AC is common and I have seen many evaporator boxes removed and “AC delete plates” installed. I’m hardly encouraging that, but if it has been done, it seems to me that is only half of the job! I even purchased a non-AC heater control a few years ago, but then realized it was way more involved than just swapping controls! Fast forward to a few weeks ago… the idle went goofy. I tracked it down to a vacuum leak under the dash in the AC controls. That leak was the last straw, so I dove in.
I popped the dash pad off and pulled the heater core box. I was expecting to buy and install a non-AC heater box, but then realized the firewall, ducting and cowl are completely different than a heater-only car. The heater core is in a different location and heater-only cars have fresh air ducts from the cowl to the vents in on either side of the dash. I changed my plan and decided to make the AC heater core box work. I pulled the box apart (mostly small screws and drilling out a few rivets). I unbolted the 2 vacuum actuators from the box and removed 2 additional actuators that are part of the system- one in the passenger side kick plate and one in the cowl. I also removed what I guess is a “mixing” door in the heater box. I’m not sure what it does… I couldn’t figure it out- so I removed it! 😊 But it did seem to rattle a lot, so I figured “one less rattle.” I haven’t missed the door!
I used the existing actuator cable to operate the “COLD/HOT” door, and 2 cables from an old Camaro to operate the DEFROST and OFF/AIR doors. (Repop Monte / A-body cables are available.) I had to get a little creative to make the DEFROST and OFF/AIR doors swing fully open and closed with the full swing of the controls, but it works nicely.
There are 2 ways to wire the blower switch. (The switches are different between AC vs non-AC and they don’t swap between the controls.) Either way gets to the same result- the blower switch operates OFF, LOW, MEDIUM, HIGH. And you don’t have to move the top control lever from the “OFF” position to turn the fan on. (I always thought that was a little weird with the AC controls.)
1. Use the existing AC wiring. Get a 4-pin connector and pin it as shown from wires in the AC blower switch connectors. (There are 2 connectors.) This method uses the AC heater resistor- I installed mine in the delete plate when I removed the evaporator housing. The high-speed fan relay on the fire wall is removed as well. (NOTE: the purple wire is “hot” when the blower is running and the other big wire runs to the horn relay- take care to make sure these can’t ground out). The blue wire is dead at this point.
2. Use the existing non-AC wiring. AC cars have the non-AC blower connector (black 4 wire plug) and heater resistor connector (white 3 wire plug) tucked up under the dash. There is also an orange 14g wire with a connector that plugs into the blower somewhere bundled into the harness in the engine compartment on the firewall. A heater resistor needs to be installed in the heater box- then plug in the heater resistor connector. Remove the purple wire from the blower and plug in the orange wire. At this point, the entire AC harness can be removed or tucked away. See my note above about the high-speed fan relay.
I bolted the box and controls back in and installed the duct work. Oddly, the Defroster duct doesn’t attach to the heater box. There is a gap between them but it doesn’t impact the flow to the windshield. I did notice the duct swings and rattles, so I put a rubber pad between the duct and the firewall and the rattle was gone. I used the rest of the AC ductwork, but I removed the 2 (creaky) vents that come out at knee-level in front of the driver and passenger. And I used black gaf tape on the plastic vent connections under the dash. This cuts down on the plastic squeaks. (Use gaf tape- never duct tape!)
I wanted to keep the “factory correct” heater hose valve but it is Normally-Open and it needs a vacuum signal to close. I hurt my brain trying to incorporate a switch and an electric solenoid to control the vacuum signal to the Normally-Open heater hose valve. (My logic: I didn’t want the vacuum solenoid activated or “on” in the COLD position- I consider this the “normal / off state.” The solenoid activates and opens the heater hose valve when I want some heat and can cut in some cold with the COLD/HOT lever… whew.) I found a factory-appearing Normally-Closed heater hose valve. I installed a micro switch to operate the vacuum solenoid. As soon as the COLD-HOT lever comes off of COLD, the switch energizes the vacuum solenoid, opens the heater hose valve, allowing coolant to flow through the heater core. To power the circuit, I used the brown “key hot” wire that was no longer needed for the AC system power.
The repop kick plates fit well. My only complaint is that the knobs for the vent cables are kinda cheap looking. There isn’t much to the factory ac kick plates (mine had been butchered with a bad speaker install, so I won’t miss them). Because I do not have fresh air vents from the cowl, I removed the top cable from both kick plates and installed black rubber plugs into the holes. Installing the driver side kick plate is a bit of work twisting under the dash. The parking brake pedal assembly needs to be unbolted (you can leave the cable alone and swing the assembly out of the way). There is a plate that covers the vent hole that needs to be removed, and then the whole assembly needs to be finessed into place.
I have driven the car quite a bit with the new set up. The controls work very well and there is a satisfying, more direct change when moving the levers around, rather than waiting for vacuum to build to open / close the various doors! The fresh air vents in the kick plates are nice too. My Camaro has them and it is nice to open them to get air flowing around your feet. There are also much fewer squeaks from under the dash (I’m a nut about getting rid of squeaks and rattles), and I get a kick looking at the heater controls! Success!