I completed a diagnostic on arrival I saw thermostat was at 73 degrees and furnace was locked out on high limit lockout what’s going on is this is a zone system and is a 100kbtu furnace with only runs going into the basement the bypass damper when basement was calling for heat became stuck open causing the return air to skyrocket above 140 degrees causing the high limit to trip. Set thermostats to cooling so this wouldn’t happen again and also manually closed the bypass because it was stuck open. System is pumping 54 degree air out of the vent and is currently on and operational at time of departure.