furnace blowing cold

Hi, y'all. I recently purchased a 2016 285 LX Prowler Lynx from the first owner. They had left it sit on a lake in NH for the past 8 years, and spent time in it with their family and grandkids. I'm now living in it full time, in WV. We stayed in it a few times in NH, and the last time was during...

Hello all, hoping for help here- We have an Oakmont 375qb with 2 thermostats. The main one works as expected. The one in the bedroom seems to have power, and when you turn it on it does blow air from the vents, but the air is ice cold. Please let us know how to run the heat in the bedroom. Thank...