Let's talk about playing the accordion with the left hand. The left hand of the accordion is really awesome. There are all of these bass notes over here, and they all do different things that are really fun.
For example, if you can see where my finger is where I'm pointing right here, there's a little divot on this particular accordion. Some accordions have gems there. Right underneath there is the C. I'm going to play the C. Moving in a diagonal line just above it is the major chord. Moving up, the minor. Above that is the dominant seventh. And finally is the diminished.
The first row that we haven't talked about yet is called the counter bass row. That is a major third above the bass note in the fundamental row which was the C that I played. So, the counter bass note will be an E. You have everything that you need right at your fingertips, literally, in the left hand to play a scale. And, with the chords you could make up a whole song just using your left hand.
A little variation on the 1-5-4 chord series for the left hand.