Propex HS-Series Heater CN18 Reset

 

The Propex HS-series heaters are extremely reliable in real-world conditions; however, we have seen instances where a fault code cannot be cleared by the normal reset process. We believe that the main circuit board gets into a kind of logic loop and becomes unresponsive to input. We usually see this during a one-flash code event but at times no code is present.

Luckily, there is an easy fix for this condition that we call the CN-18 remedy. If you have been unsuccessful resetting the fault code from the system, please try the following:

• Leave 12V power connected to your heater.

              *Note: Please use caution not to inadvertently touch any of the electronics except those discussed below.

• Remove the cover on the heater body to access the interior electronics.

• Take note of the three-pin socket labeled CN-18 on the circuit board next to the thermostat connector.

               *Note: There may or may not be pins (see photos below).
               *Note: The pins of the three-pin socket may be covered in clear silicone protectant.

 

• Using a paper clip or screwdriver tip, jump the center pin and the pin closest to the thermostat connector. (See the photo below showing you which pins you'll be jumping.)

                *Note: If silicone is present, the ends of the paper clip can poke right through to contact the pins.

 

• Hold the connection for a few seconds and the fault light in the thermostat should go out.

• Reinstall the access cover and try the heater.

 

The one-flash code should now be completely out of the logic circuit's memory and the heater should run as normal (assuming the conditions that actually caused the fault have been remedied).

 

OR: 

 

 

If there is no change after the CN18 procedure, try testing the Propex thermostat.