Closing the chapter on this issue........
Thanks to the advise by Joe and others I was able to fix my problem and I am happy to say both heat pumps are now working.
As noted in my earlier posts, Dometic tech service helped diagnosed the problem to be the communication cable that runs from the front heat pump unit to the back unit. This cable looks exactly like a telephone cable with RJ-11 male connectors on each end. These cables as purchased from Home Depot, Radio Shack etc WILL NOT WORK as the connectors are reversed from one end to the other. For the cable to work correctly the connectors must be wired "straight thru" so that the 4 colored wires are in the same pin locations on both RJ-11 connectors. This is quite easy to remedy but does require a special tool ($28 @ HD) that allows one to strip the wire and crimp on a new connector (Bag of 10 $3.98 @ HD).
An easy way to check if your cable is "straight thru" is to set both connectors side by side on a table with the spring clips facing down. Look at the colored wires and if both connectors have all wire colors in the same sequence ie black on the left followed the three other wire colors you have a "straight thru" connector and it can be used to connect your Dometic HP to the 5 button Control Center. If the wire colors are reversed from one connector to the other it will be necessary to get the tools mentioned above, cut off one connector and crimp on a new one.
The replacement cable that I got at HD was like this and not "straight thru" so I had to modify it first. Then I had to string this cable from the front unit to the back. This was done by using a fish tape and pulling the new cable thru the cold air return in the ceiling. I removed the covers from each heat pump on the roof (be very careful when up on your roof. It's a long way down). Next I removed the cold air return ducts on the ceiling inside the MH between the front and back heat pump. This allowed the access needed to fish the new cable.
Once the new cable is plugged in do a reset on the 5 button control center (hold the Zone and Mode buttons down while turning on the 5 button control center. You will see the letters FF and once you release the Zone/Mode buttons you will then see Zone 1 & 2 displayed).
It's a great feeling to fix the issues that come up from time to time on our MH's. Best of all the knowledgeable folks on this forum have saved my bacon and $$$$$ on more than one occasion.