I have a thermostat that I set for 75 and after 10 minutes the furnace turns off and the temp inside the RV is not even close to 75. What could the problem be?
The manual thermostats are notoriously unreliable setting-wise. Suburban isn't even putting numbers on theirs anymore - just gray bars to indicate higher heat settings. I'd say if you turn the thermostat up and it reaches a comfortable temp then you're fine.
And, yes, the thread should probably be moved to Tech Issues.