Very rarely we've seen a running issue where your Propex fan may start acting possessed and cycling on and off in one second bursts regardless of the settings on your thermostat. We suspect this happens when the heater has been started with the battery in a discharged state. The fan spins up to begin its pre-combustion purge as normal but there is not enough battery charge to complete the cycle. It's almost as if the logic circuit on the main circuit board enters a manic loop trying to complete the purge. Take a listen to the fan in this video:

If your heater is exhibiting this symptom, there are a few things you can try:

• Disconnect the 12V power to the unit (you can just pull the inline fuse), charge your vehicle's battery and then reconnect the 12V to the Propex. Perform a code reset procedure before you try to start the heater. Now try to start the heater as normal. Didn't work? Move on to the next step.

• Disconnect the 12V power to the unit by pulling the inline fuse. Leave disconnected for 24 hours. Reconnect the 12V power and perform a code reset as in the link above. What you're going for is a complete capacitive discharge of the electronics of the heater in an attempt to get the logic circuit to 'forget' what it was trying to do. Didn't work? Try the next step.

• This last attempt is much more invasive so please only attempt it if you feel comfortable around electronics. Please ensure you're properly grounded and follow all electronic repair best practices. Disconnect the 12V power. Remove the main circuit board from the unit and place in a static-proof bag. Leave for 24-48 hours. Your goal is to achieve the capacitive discharge we talked about above. Reinstall the board and apply power. Perform a fault code reset and try the heater. Didn't work? Uh-oh...

• If the full capacitive discharge didn't work it's time to replace the main circuit board. Look for a number on your circuit board beginning with 770.xxx (the "xxx" will be a three-digit number like '215' or '531', something like that). 

Alternatively, you can send your heater in for service and we can perform the replacement of your board. 

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