How to reset the DUAL light flashing on a Honda CRV 57. Follow these instructions at your own risk.
Turn the car off.
Hold down the off button on the a/c unit.
Turn car on to II position.
Keep holding the off button and press the rear/wing-mirror defrost button 5 times within 10 seconds.
Let the car test all the blowers etc.
It should switch itself off after about 10 seconds.
Switch the car off.
Switch it back on again and it should be fine.
If you get a error message then something is wrong or if the light keeps coming back on then I would recommend you take it to a dealership.