I added A/C to my car and wanted to share with you what I learned.

It is a pain in the butt, but doable if you're patient. It's also a great way to learn about how the system works.

I was lucky enough to find a 73 Centurion 2 door hardtop for sale as a parts car. I was also fortunate enough to have a neighbor who let me hide this treasure in their garage while I did the conversion. I think anyone considering the upgrade should get a parts car. If you want to invest the time you could use all your non-A/C parts to reassemble and sell the parts car when you're done. I took so much from that car that it went to the great junkyard in the sky when it was done. Don't worry, this car was beyond repair before I began.

I moved the parts over in 3 steps, plumbing, venting and wiring. For each stage I disassembled the parts car first, learning how it should be and what fastners are a pain. I then painted the parts and disassembled my car. Then I installed the freshly painted bits. Be sure to release the pressure from the cooling system before you put in the hot water cutoff valve. I almost forgot and cut the hose while under pressure. The vacuum system has roughly double the number of hoses when you add A/C. There is 1 tricky vacuum line that needs to go to the hot water shutoff valve. Without this the A/C will never be truly chilly.

Each stage had it's difficult bits. The plumbing and ducting around the hood hinge required unbolting the hinge, holding the hood up while my wife stuffed the new heater core and evaporator housing on the firewall. This had to be done twice because the opening for the fan is bigger with A/C. The mechanism for the recirculating setting is particularly buried. I almost skipped it, but I can't stand doing a partial job.

The venting (all of the ducts and flaps under the dashboard) was probably the hardest part of the entire process. It's necessary to disassemble the dashboard down to the firewall. Everything has to go. There are ducts that are part of the sheet metal work of the firewall. I had to make block off plates for the passenger floor vent and cut openings for the A/C ducting and the inside half of that recirculating mechanism. The heater box has 2 studs that go through the firewall and secure the air box on the other side with nuts that would be easier to get at if you pulled the engine. A/C cars have 2 vents for the passenger (only 1 without A/C). The instrument faceplates are also different on an A/C car as they have the vents, fins and openings for the on off lever. The plate that fits under the steering column is different as it incorporates the vent that blows between your legs. You can also expect that the air hoses will crumble to dust after 30+ years and will need to be replaced. Then there is the control center and it's octopus of hoses to route and connect. I tested each hose, and each actuator while they were out of the car. The actuators were all fine, but a couple of hoses wouldn't hold vacuum. I also replaced all of the foam insulation on the flapper doors.

The final step (wiring) wasn't so bad because I took the entire wiring harness from the fusebox junction forward. I labeled each connection before I disconnected it. There are a couple of things to watch for. A/C cars have 4 fan speeds, non-A/C have 3. There are new connections for the compressor clutch, pressure sensors and the throttle pusher thingy.

I did all of the work and took it to my mechanic to check everything and convert it to the new freon.

Was it worth it? Hell yes. I tested it on a 75 degree day, on the highway in recirculating mode and the fan on low. A thermometer in the vent got down to 34 degrees before I chickened out and took it off recirc. There is a sensor that's supposed to shut the compressor off before it ices up, but I didn't want to risk it. That's frosty baby.

People ask why I would go through the trouble to add A/C to a convertible.
After all if it's hot you can put the roof down. There are 4 reasons. First there are days when it's too hot to sit in traffic and bake. Second there are hot rainy days. Finally there are those in between days when the windsheild fogs up and A/C is the only way to keep it clear. Finally and most importantly because my car didn't have it.

I wouldn't recommend it, but I wouldn't call it a deal breaker either. Because of the number of little bits involved I think the only way to do it is with a parts car. I think any B-body Buick (71-76) would do.