One good way to lube roof air conditioning blower motors is to use a Zoom Spout Oiler container to get some lubrication on the blower shaft near each end of the motor, and then work the oil in by rotating the blower. Compressor is sealed and not able to be lubricated.
Clean roof air evaporator coils for improved cooling and lower demand on units to cool. Use aluminum-safe foaming coil cleaner, like Arm & Hammer Biodegradable HVAC and Air Conditioner Coil Cleaner Foam Aerosol Spray, No Rinse. Coil can be accessed by removing big plastic cover and than the metal cover sealing the blower. Some cleaning may be achieved from inside coach by spraying the input front surface of the coil.
Modify ceiling air intake filter so that all air flows through filter and not around. Some install a plastic screen above filter material to keep filter in place
Many think WD-40 is a solvent, not a good lubricant, and is over-marketed.
https://www.reddit.com/r/YouShouldKnow/comments/1wa9a6/ysk_wd40_is_a_solvent_not_a_lubricant_mistaking/