What To Do If Your Propex HS-Series Heater Malfunctions With No Fault Code Present

If your Propex HS-series heater is having issues but no diagnostic fault code is showing on the thermostat indicator light, there are a couple quick diagnostic tools you have in your toolbox.

First:
Is the ambient temperature warmer than 80F? The upper limit of the Propex thermostat is 80F to limit the overheating of the cabin space in case the thermostat is left on high. You have a couple choices to test heater operation in temps over 80F. You can wait until morning or a cooler time of day -or- you can use this high tech, super-sneaky way to trick the thermostat into believing ambient temperature is lower than actual: take a piece of ice and gently blow across it so that the cool air hits the snowflake icon on the thermostat. The temperature sensor of the thermostat is the blue snowflake on the thermostat.

Second:
Disconnect the heater 12V power (usually by pulling the inline 5A fuse) and reconnect after a few seconds. The internal fan should run for about half a second to let you know that the unit is ready for operation. If you DON’T hear the fan run, it's likely that the surge fuse is blown and needs replacement. You can source a replacement blow fuse and follow our fuse replacement article.

Third:
If neither of the previous two fixes the issue you can test the thermostat with the following procedure:

 - Disconnect the 12V power to the heater (usually by pulling the inline 5A fuse)

 - Take a small paperclip or jumper to jump between the brown (12V+) and blue (heat function) of the thermostat harness connector

 - Reconnect 12V to the heater

If the heater starts up as normal it is possible that your thermostat is bad.  You can find a replacement digital thermostat here or a replacement analog thermostat here. If your heater is under warranty, contact support at support@propexnorthamerica.com.

If the heater does not start as normal there is something (or a combination of things) happening. Check the installation and operation manual to ensure that your installation is in line with recommendations.

The vast number of heater errors will display a flashing fault code to help with diagnostics. No flash failures are rare and usually covered in the procedures above. If none of these things work for you, it is possible that your heater needs repair. We offer heater repair services at reasonable labor rates. If you believe you need repair, contact us at support@propexnorthamerica.com. Please only contact us AFTER you've tried the above operations.

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