rubber edpm roof completely seperated loose

It's a big job to re do everything and if you did re do the whole roof you would buy new epdm, so I would do the same thing. Open it up like old school heart surgery and sneak in there with contact cement. NO, contact cement WILL NOT hurt the epdm. The reason Dicor recommends their adhesive is because they feel that people would not be able to handle the one chance characteristic of contact cement along with a huge piece of stretchable material. When it sticks it's stuck! I contacted them and that's what they told me.

I replaced a roof on an old TT project and used contact cement with epdm. It was tight and smooth as a babys butt. I only did a couple feet at a time. If you have used contact cement it will be no problem. If you have never used it get some type of material that will let you practice first.

While I agree mostly with rjxj, I disagree on the contact cement part. You don't want a cement that sticks on contact if the Dicor cement lets you move or slightly slide or even pick up and lay back down the material once it's laid down. Otherwise you might wind up with a huge bubble, wrinkle or a huge gap down the cut seam.

I can't see your roof, but you might be better off cutting a large T or even a capital I in the membrane so it's easier to peel back and get under with the glue.

Before you put knife in hand, it may be a good idea to get an opinion from someone in the trade that does this type of work.

What first occurs to me is that injecting adhesive through the membrane may leave a smaller repair to the membrane, rather than cutting a new seam and be just as effective.

If it's not leaking, my first thought would be to locate where the air is getting under it and seal that area only. If you can eliminate the entry point for the air pocket you should not have to worry about the rest of the roof. Check the front cap area if it's starting there. You might need to unscrew the trim and reposition the rubber and glue it as far back from there then replace the trim and reseal with dicor self leveling caulk over all the screws and trim.

A quick fix may be as simple as applying some eternabond down the area where you suspect the entry point of the air.

If it were mine I would not attempt to cut the membrane as a fix.

The first thing is to eliminate what caused the membrane to come loose, and that is washing the roof with the wrong chemicals that actually dissolved the clue holding the membrane to the wood. Use whatever you used before, and your repair will fail, too.

I have read that the air pressure created when driving causes this and have also read that the air comes from around the roof ac unit because supposedly they aren't sealed around it. I don't know if either is true . Inspecting it visually everything else looks air tight

I have always used dishwashing liquid to wash it

A pressurized leak test may turn up any air infiltration to the underside of the membrane. How much of the membrane is moving when you drive? Is all of the bubble you see in the center?

The roof around the ac is glued the same as the rest of the roof. The membrane is stretched over it and an X cut in the membrane for the opening and the flaps are stapled to the wood or metal framing underneath, then the ac is set on top with a collapsable gasket, so I doubt very seriously that the air is entering there, or you would also be leaking around the ac when it rained. If there is a tear anywhere near the roof vents or the ac then maybe air could be entering there. But then again no leaks present. I would carefully examine the front seams.

An air pressure test from inside may show up where the air is getting under or may not, since the air is obviously getting under the roof while towing. That would lead me to beleive that it has to be getting under the roof on the exterior.

It's possible that the air is entering around one of the running lamps close to the roof line and making it's way underneath the membrane. It may be difficult to find but the only options are to find the entry point or replace the roof membrane being certain it's properly glued.

Keep us posted on what you find. If you take it in they will just recommend replacing the roof. As a last resort, you might check with your insurance to see if it's covered, as it will eventually lead to a bigger problem.

Or, maybe you could find a low hanging branch to drive under, then it would be covered for sure ! LOL

Not necessarily air getting in under the membrane, but rather the vacuum formed from the air flow over the trailer.
As has been said. I think contact cement would be real trouble unless you were to cut in an H pattern and laid the membrane back, and even that would be very hard to get back exactly like you lifted it. Contact cement means what it says. On contact it's THERE!
I think the best suggestion is contacting the pros and ask about injecting adhesive, then you only have to patch the injection holes.