Tech found ignition control board bland with 24v going to board. Tech replaced board and found system running but tripped on high limit. Tech went to check airflow out of the vents and found 5 vents closed off. Tech also found low stage pressure slightly high at 6 and adjusted. Once vents were open and pressure adjusted, system ran without tripping. Tech also noted high stage maxed out at 9.75. System is now heating properly.