I don't think it's the heat as much as the movement. Steeping is nothing more than molecules from different flavor ingredients bonding together. If you can keep a constant movement of the juice, it will accelerate the bonding process. Sitting idle, the particles stratify and don't bond with each other as well.
Humm
The way my clothes dryer is bouncing I will have to put the new juice in something and set that on the clothes dryer the next time I use it.
Could take a week off the steeping time.