What chassis is your coach built on ?
If it's on a Freightliner chassis , then the air system dryer is probably on the drivers side frame rail , beside the transmission and ease of service depends on the dryer manufacturer . Two manufacturers are covered in this PDF.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.