Replacing RV Air Conditioner units

[ScottandLori]

We have owned a 2005, 36 foot Mobile Suite (RS3) for about 2 years now. The front air conditioner in the bedroom area (Zone 2) appears to be original but will only run for a short time before making a new different noise then causing the breaker to blow. The rear air conditioner in the main living area (Zone 1) is running but the two air conditioners do not communicate well. I have already replaced the thermostat. We have watched several youtube videos showing how to remove the old AC units and install new ones, but all of them remove the anchoring bolts from the inside, in an access hole through the ceiling. We have a ducted system and we can not see inside how to reach the units from the inside. How are these units mounted or how do we get to them? There are no visible access ports to the units from the inside.