When I arrived at unit, the furnace was in lock out mode. I reset the unit and turned system on in heating mode. I used door clamp to keep system on while I diagnose. I checked continuity through all my pressure switches. All my pressure switches were working. I took off inducer tube and blew through it of any debris caught in tube. I cleaned flame sensor, just to do a maintenance that was needed on two year old system. I stayed at home for hour and half and didn’t have system shut off. No error codes were provided at motherboard. May be excessive winds shutting off system. System is working and I told owner if it happens again to call front office. Charging $29 diagnostic.