Jandy LXi Air Flow Fault: LED Single Flash Troubleshooting

What the Air Flow Fault Actually Means

The LXi has an air pressure switch that verifies the combustion blower is moving adequate air through the system. The blower delivers combustion air to the premix burners and purges the combustion chamber before and after ignition. If the pressure switch does not close, the ignition control will not proceed with the ignition sequence.

The LED on the ignition control module will flash once in a repeating pattern to indicate this fault. The LCD display may show FAULT-CHECK IGN CONTROL, which covers multiple possible causes including air flow problems.

Step-by-Step Troubleshooting

Owner-Level Checks

Check for obvious obstructions

1. Inspect the exhaust vent grill on top of the heater (outdoor installations) for debris, leaves, bird nests, or insect nests.
2. Check the rear louvers which supply combustion air to the burners. Make sure nothing is blocking them.
3. Verify the heater has proper clearances on all sides. Objects placed too close can restrict air intake.
4. For indoor installations with vent piping, inspect the vent termination point for blockage.

Tech-Level Checks

Inspect the pressure tubing

1. Locate the gray flexible tube that connects the blower housing to the air pressure switch.
2. Check that both ends are securely connected. A disconnected tube will prevent the switch from sensing pressure.
3. Inspect the entire length for holes, splits, pinches, or kinks. Replace the tube if damaged.

Test the combustion blower

1. With the heater calling for heat, listen for the blower to start. It should run during the pre-purge cycle before ignition.
2. If the blower does not run, check for 120VAC or 240VAC at the blower terminals (verify which voltage your unit is wired for).
3. If voltage is present but the blower does not spin, the blower motor has failed. Replace it.
4. If the blower runs but sounds weak or slow, verify proper wiring for 120VAC vs 240VAC. A 240V blower connected to 120V will run at reduced speed.

Test the air pressure switch

1. With the blower running, check voltage at test point 11 on the wiring diagram. You should see 20–28 VAC.
2. Move your meter lead to the NO (normally open) contact of the air flow switch. If 20–28 VAC is present, the switch is closed and working.
3. If there is no voltage at the NO contact with the blower running, the pressure switch contacts are open. Check tubing first, then replace the switch.
4. If the switch shows closed but the ignition control still shows an air flow fault, check voltage at test point 12 on the ignition control. No voltage means a bad wire harness. Voltage present means a faulty ignition control.

Check for internal blockages

1. Inspect the heat exchanger flue passages for blockage from spider webs, debris, or corrosion.
2. Verify correct vent sizing: LXi 250 = 6″ diameter, LXi 400 = 8″ diameter.

Common Parts That Fix This Problem

• Combustion blower motor
• Air pressure switch
• Gray flexible pressure tubing
• Ignition control module (if switch tests good but fault persists)
• Eight-pin wire harness

How to Prevent Air Flow Faults

• Keep the vent grill and rear louvers clear of debris. Inspect seasonally.
• Check the pressure tubing annually for deterioration.
• Maintain proper clearances around the heater per the installation manual.
• For indoor installations, ensure combustion air supply openings meet manual requirements (which exceed CAN/CSA-B149.1 minimums).