HotRod Heater /Air System

OK, I had run into a mysterious area last week that left me wondering. I had three wires hanging down from my heater / AC system (after it was installed) and I didn't know what they were for. One was Red, one was Blue and one was Yellow, with bullet type connectors on each and the Yellow one having a ground connected to it. I had not checked them out where I could have easily taken the unit apart before installing, and using a multimeter to try and figure them out didn't shed any light on their purpose. I dallied too long, maybe should have posted here to see if anyone had any answers, and ended up at the point this weekend where I had to take the unit back out (remove AC and heater lines, etc.) to take it apart to try and figure out what they were. I came to the question when I noticed that the male bullet on the blue wire would mate nicely with a female bullet on the blue wire coming from the AC control (that I thought went to the trinary). It seemed like synergy with a blue wire with mating connectors should be stuck together, but didn't make sense.

Mystery solved, the Yellow is a ground. The Blue and Red wires have to be connected together to make the Yellow/Red/Orange wire trifecta that is the fan speed control work. Not as intuitive as I had hoped. So, they are now connected together, secured together and tucked up and out of the way.

My theory is that those are perhaps the original single speed motor wires on the system and connecting them together and putting in the Yellow/Red/Orange trio that result in different fan speeds is how Hot Rod Air repurposed the motor, I can't think of another reason why they would be sticking out with connectors rather than just connected together internally.

So anyway, posting this in case it helps someone else in the future.