Dometric ccc2 thermostat

If the temperatures are far apart, it will only run on hi fan. Adjust the Tstat temperature only a couple degrees above the room temperature since you are currently trying to heat your rig. Did this slow the fan down? If not, Try a system reset...with the Tstst turned Off, press the zone and mode buttons at the same time. IniT should display and then less the on/off button. Does it now control the fan speed? If not then the dip switches on the control board are not set properly.
Where in B’ville are you?

Thanks for the info. I'll try it when my brother returns with it. After pressing the buttons at the same time you said the "IniT' should display, is that the thermostat screen? and then "less" the on/off that must be "press". I live off Gumlog. Thanks again

Yes on the screen. I developed Ivylog Estates, but live on the lake.