Doors – Air comming in from door side

Before concentrating on an air pressure solution, I would eliminate two other possibilities:

1. The handles on the inner and outer doors are interfering very slightly with each other. Check the height of each handle above the sill, and the spacing between the two doors when closed;

2. The act of closing the inner door distorts the door frame slightly, shifting the outer door from the "fits well" category to the "fits with great difficulty" category...

I have been installing doors and windows since 1988. Ii sounds to me like you have a bad installation. It also sounds like the doors were pre-hung but standard size since the had to cut into the slab. Sliding patio doors are 79-1/2" and 81-1/2" net height standard sizes. A standard size French door is 81-3/4" net height. Normally when replacing a sliding door with French door the doors would have to be cut down so the overall unit would fit the existing opening.

Often installers will not flash above the door, just caulk. It should always be flashed above the door. If the doors are properly installed you will not see any light coming in. Another clue that the door was not sold correctly is the time it took to install it. About 4 hours would be realistic.

You have some options, but don't wait too long. Most states, I think, require a contractors bond. A complaint to your state's labor department can help you with filing a complaint against this contractor. This can tie up there contractors bond until the issue is resolved. Also it has been my experience that people who could pay with cash or check will use a credit card because if they feel the product or performance was not what they were sold a complaint to the credit card company will remove the purchase amount from the offending companies bank account and will not release it until the issue is resolved.

Hope this helps.