1. No problem, normal operation
2. Blown fuse.
3. Faulty blower
4. Blocked venting
5. Blocked air inlet
6. Disconnected, damaged or blocked tubing
7. Incorrect air switch setting.
8. Faulty air proving switch
9. Incorrect air switch wiring
1. Hold 65 will normally be displayed momentarily during the drive to light-off.
2. Check Fuse "A", blown fuse prevents blower from operating.
3. If Fuse “A” is good and blower remains off, check 120VAC supply to blower, if present replace blower. If blower is on proceed to next step.
4. Check for blockage of the exhaust vent.
5. Check for blockage of the air inlet.
6. Inspect the clear vinyl tubing connecting the air switch + and – ports to the air metering elbow. Condensation or other foreign matter may be obstructing the tubing, preventing the switch from sensing differential pressure caused by air flow through the metering elbow.
7. Contact NTI technical support.
8. If venting and air inlet are clear, temporarily jumper the air switch. If the unit lights and operates smoothly – replace air switch. If the unit fails to light or lights but runs rough or abruptly shuts down – check boiler internals for blockage. WARNING Only jumper the air switch for diagnosing purposes.
9. Check that the red and orange wires are connected to quick connect tabs 3 and 1 respectively.
