Roof top AC units

JCMack wrote:
The roof AC units on my 06 Mountain Air gas motor home are losing there cooling capacity. Can they be recharged or do they need to be replaced

The first thing I would check, if they are ducted, is if they are leaking cold air around the ducts at the unit itself. This requires you to remove the bottom cover and look up in to the unit and see if there are any cracks where the cold air is blowing in to the exhaust area or roof frame, rather than directly in to the duct.
The next thing to check is to pull the cover off on the roof and check that the coil is clear of any debris.