Thanks! No, there are no error codes. It's as if it thinks it's working fine. I did do the breaker reset - no luck. If it's a relay board... is there any hope that I can acquire this part and replace it myself, or is it soldered or otherwise complicated? If it's "plug and play", I can handle it.
Thanks again!
Is the "temp" icon flashing on the control panel? If it's not that or any other error codes on the control pad then you would need to do some tests with a meter in the control box.
Try taking the filter out and resetting the breakers.
Most likely problem is a bad heater relay board.