Make sure the hot water valve is all the way open. Check the hoses,
sometimes they have screen washers in them that can be plugged. Hook
up a garden hose and verify that water is indeed flowing. If all that
works, and you are getting at least some hot water in, it's likely the
solenoid/valve for the hot water. They don't cost too much, if you can
DIY. Otherwise, I'd either put up with it or get a new machine, as at
17 years, I doubt it's worth the cost of a repair call. I'd bet it
would be min of $100 to fix.