Upon arrival, inspected system and found system in 33 lockout. Air filter was decently dirty. gas pressure was 3.52 its within spec but lowered to bottom line 3.20 to decrease temperature rise. Unit heating at 60° rise with no filter after it passed 70° rise with the dirty filter i removed it and it dropped. Unit is heating adequately without a filter and thermostat reading 67 while fieldpiece sensor reading 67 thermostat settings seem accurate.