Sealing around roof AC a No-no?

The AC unit has a pan on the bottom, the drain allows water to exit the pan onto the roof. There is about 1/2 inch gap between the roof and the pan (the gasket thickness) That gap is what you don't want to seal. If you are doing liquid rubber on your roof, well worth your while to remove the AC unit, ( set on a piece of cardboard or plywood) paint around the opening, use new gaskets (not expensive) and put the AC back in place. OR paint right up to the edge of the AC base. The roof under the AC has not been exposed to the elements and should be in better shape than the rest of the roof.

Another discussion here: A/C side view
-"old-bisquit- posted this drawing that may help to see the layout.

You don't seal around your AC. It has a gasket that prevents the water from getting inside. Your AC gasket is about 1" thick. You set the AC down on it and tighten all four bolts, like you would a car rim - each a little at a time. You tighten it down so there is 1/2" between the AC and the roof. Do not over tighten!!!

When 14 our twins replaced both gaskets by themselves with me looking on. The gaskets were $20 each and hope they will last another 15+ years.

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