@Burnooger &
@kennyatshop, a possible fix is to reprogram the defroster.
This is how it was done in 8th Gen Civics. Not sure if there's anything like it for our 11th Gen models.
- With the key in the "Off" position, set the controls as follows.
- Blower control to "Off"
- Temperature control to coldest
- Mode button to select panel vents only (cannot be selected with the key off, so select this before turning the engine off before starting programming)
- Holding down the recirculate button AND the A/C button, START THE ENGINE. (Continue holding the two buttons) The recirculate button indicator light will flash for about seven seconds. Then the A/C green indicator light will flash on. The defroster is now reprogrammed!