A/C, H/P only operating on high speed

[Beamer54]

We have a 2014 27" FB Flying Cloud with a single A/C-HP unit. It connects to a Dometic CCC2 thermostat that shows 3 available fan speeds - low, medium and high with an auto function as well. We can only get the fan to run on high regardless of the thermostat fan settings. Auto always runs on high speed.
Dometic has told me this fan can only operate on low or high. Does anyone know how to enable the low fan speed?

[Jim Flower]

Auto Fan
When auto fan is selected the fan speed will vary depending on the difference be- tween the temperature set-point and the room temperature. In auto fan the compres- sor and fan cycle On and OFF with the thermostat.
When the difference is:
8o or more
5o to 7o
4o or less
The fan operates on HIGH
The fan operates on MED
The fan operates on LOW

This is copied from the manual. Perhaps it is just the temp differential. If not try a thermostat reset.

System Reset Procedure
When your unit was installed the appropriate dip switches on the electronic control board were turned on to match your system con guration. Any time these settings are changed, a system reset will need to be done before the CCC 2 thermostat will recognize the updated selection. To do a system reset:

Make sure the CCC 2 thermostat is in the OFF mode.
Simultaneously press the MODE and ZONE buttons. The LCD will display “IniT” and all available zones.
Release the MODE and ZONE buttons.
Press the ON/OFF button to exit system set up.

I don't know if any of this will solve your problem but it is worth a try.
Jim