suburban sfv 35fq rv furnace dead

I have a 6 month old 5 wheel with a non functioning furnace. It work fine, then one day it shut off before coming to temp. The following morning it lit and started heating, but shut of after a few minutes before it reached temp. It has shown no signs of life since. My thermostat runs both my AC and furnace. The AC works via the thermostat. I checked the thermostat wires. There are 3 wires coming in. There is a 3 junction block for the 3 wires. Looking at the back of the thermostat, a green wire is labeled 12v, then the orange wire is labeled common, and then the red wire is labeled 12v. I connected the orange and green to my fluke meter and it read 4.8 volts DC. I also metered the orange and red, and it read 7.8 volts dc. I tried shorting the green and orange, waited several minutes and nothing happened. Then I shorted the orange and red, again waited several minutes and nothing happened. Since the AC works via the thermostat I had expected one combination of wires should at least have started the AC fan. From other furnace postings I expect I will need to access the furnace, but I have no clue how. I can locate the exhaust, but there is no access. My water heater is directly to the left, might I have to remove it to access the furnace?
This is in a Forest River Wildwood Heritage Glen 327 RES. Any help would be appreciated, Thanks