A/C fan runs then stops

95 Land Yacht 30 ft, front roof mount A/C fan runs for about 10 seconds then stops. Compressor never comes on. Checked the black capacitor with ohm meter, appears ok. Checked the dual capacitor with ohm meter appears ok.

Removed leads on all and discharged before checking. Measured PTCR as 47 ohms (approx).

Any clues to where to look next?

Unit is Penguin DuoTherm with thermostat in the ceiling vent cover.

Thanks.

Tim