Sometimes these things are fun to find, I helped an older couple that were having problems, couldn't put water in their tank. The drain valve was open and water kept pouring out of their tank. I finally found a valve way back under their bed that you had to access through a door. I have long arms but had to get my shoulders trough the access to reach this valve. There was no way this old couple would have reached it and spotting it was almost impossible. If it were mine I would have made some sort of handle so you could reach it easy.
Best I could say go to your generic owners manual it should get you close to where they are.
Think about things before you do them make life easier not harder.