Dash air? I have an Axis, so the setup is probably a bit different. I had a similar issue, and it turns out the ducting had slipped off the vent housing directly behind the dash. I had two like that, and there was nothing holding them onto the vent, which probably explains why they slipped off. Checking the situation requires a bit of flexibility.
If that doesn't help, it might be where the ducting attaches to the air unit, or something entirely different!