Hi, I'm Bill Walker. I'm here to show you how to clean horizontal blinds when they are still hanging up. You will need a bucket, cleaning cloths, a vacuum cleaner, and mild dish washing detergent. First pour some detergent into the bucket and fill with warm water. Lower the blind and close the slats. Now, take the brush attachment of the vacuum cleaner and vacuum the dust from the blind. Now, open the slat so they face the other way. And then vacuum this side also. Take the cloth and wet it with soapy water. Wash the slats with the cloth. Next, take some clean water and rinse the soap off the slats with a clean cloth. And that is how to clean horizontal blinds when they are still hanging up.