am having difficulties with a carrier roof ac unit. the roof opening is letting in water. have tried everything, no luck. last resort-want to seal the entire underside with Great Stuff foam, but don't want to block the condensate drain. no schematics, or model no. It was installed by previous owner, late 2002. any ideas?
First check the four screws holding the unit to the roof. Hand tighten them if they are loose. If they are tight what most likely happened was they were over tightened during installation crushing the gasket seal. Trying to use caulk or foam to reseal usually causes more problems than it cures.
The only real fix is to replace the gasket and install it according to the directions.
Check that the bolts that hold the upper and lower unit are tight. You need to remove the inside cover to do this. The bolts loosen up over time and should be checked yearly or if you have a leak. The foam gaskit that seals the AC to the roof needs to be compressed, but not compressed too much. If the seal is bad you will need to get a new one to fix the problem properly. Carrier has a website where you can get the owners manual.
http://www.airv.carrier.com/cac/home/0,2982,CLI1_DIV46_ETI1977,00.html (//%22http://www.airv.carrier.com/cac/home/0,2982,CLI1_DIV46_ETI1977,00.html%22)