Got a service call from a client lady who was always complaning about no air. The diffusers were about 20 feet up because the building was an old department store now being used as an office building, Large open area with many desks. What to do? there was no way I could reach those diffusers but I had to prove to her that air was coming out. I found a ceiling T bar cut the end to make a hook then put toilet paper on the end. when I talked to her I said I had a special adjustment tool with me I proceeded to adjust the diffusers and she could see the toilet paper waving and fluttering. She was a happy customer. being a service mechanic you have to adapt, improvise and be able to BS at times when you can't spend any money to improve the situation.
Roger