Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence
Flight Crew Overcame Equipment Problem; Flight Crew Diverted
Aircraft; Weather
Noticed an 'el mstrm nse up/dn' amber CAS lite. Soon the autopilot kicked off. Reset pitch trim and FGC1 and 2 lites on. The elec and manual trim were frozen. We followed QRH but still no control. We elected to descend to a warmer alt and divert. At around 15000 ft the trim was regained. We flew normal landing. We had no autopilot after pitch trim was disconnected until we regained pitch trim.There probably was a malfunction of the trim motor heater which we would have no indication of in the cockpit. Since we had no idea what was causing the malfunction we diverted to a suitable alternate to avoid RVSM airspace. Alt control was at times + or - 100 feet.
GIV-SP First Officer reported pitch trim became inoperative in cruise; flight crew decided to divert and regained pitch trim after descending to a warmer altitude.