1987 hi lo roof sagging
 

bought a 87 hi lo were ac unit on roof is starting to sag in the middle are the a fix for this also going to recoat the roof what is a good sealer to use was think maybe sta kool or kool seal thanks for the help

Sounds like you may have some water damage, either from a leak around the unit or from the unit itself. They are known to build up condensation and it doesn't drain properly.

Kool Seal seems to be the sealer of choice on the forum.