Do not waste dollar one on the factory system.

What you'll find is that the parts are now made from unobtainium.  The stuff's 50+ years old, its not reproduced (or not reproduced well), and to say its dated technology is kind of like calling WWII a minor skirmish. 

My advice would be unload whatever parts you have left of the factory system on eBay and use the proceeds towards one of the aftermarket systems. 

Ditto what TKO said. I keep using mine cause it came with the car 40 years ago when I got it. But it is deteriorating fairly rapidly now. The box is been held together by fiberglass patches and the vacuum actuators are wearing out.

HudginJ3 wrote:

There are 2 systems other than the factory. Vintage Air  and Old air Products. They have a lot of info on the Internet. I have the factory system with Old Air Products replacement parts to keep it going, so I have no preference.

Are you saying you have some factory and some aftermarket? Sounds like that might be better according to what I was just told about having to start all over with vintage Air.

For my factory system, I was going to have to buy a new evaporator and all the parts for under the hood minus the compressor mount. It added up to more than the cost of the Vintage Air kit. With  the servo motors, for moving doors and changing modes, the cables and vacuum tubing is gone.

The Control switch is all that will be used from the original system if a Vintage Air unit is bought. And it will need some modifications that are spelled out in the directions.

I have the Vintage Air Gen 4 set up for a 67 with factory air. The instructions are great. I had one of the hard lines that arrived damaged, talked with Jegs and Vintage Air on a 3 way call. Without fuse, feuding, or fighting, it was warranted out and a replacement was sent. I have 10 months of use and 5200 miles on it.

It does good on a cloudy overcast day. It does good if the car was cool from being in the garage. It struggles cool the car down if it’s been sitting in the blazing sun of Houston in the low 90’s.....hasn’t gotten hotter yet!! 

To add some numbers, I borrowed a digital thermometer from a guy at work. It gets calibrated yearly for measurement purposes. I used it in my truck on the way home from work. 2014 F150 crew with 98k, the air at the center registers dropped to 46 quickly. After 45 minutes of driving, it was down to 43.6. In the Mustang, after 30 minutes of driving in the afternoon, it was down to 44.3. Both were on recirculate and just below high.

It seems like both should blow colder and maybe the old R12 systems did....or it could have been the thermometer I was using at the time.