The fear of chairs is called Cathedraphobia. This is a sub-branch of general furniture fear called epiplaphobia and characterized by the anxiety towards empty chairs, mainly antiques. It manifests through sweating, shortness of breath, or anxiety.
As with most phobias, the fear of chairs is almost always accompanied by a fear of losing control. Those suffering from a fear of chairs are often afraid they can’t control their reaction in the vicinity of certain chairs. In other cases, just thinking about certain chairs can trigger this fear.