Hello,
The HVAC is an older template, and it doesn't use the predefined template colors feature. However, you can create your own template colors. From the Joomla administrator panel, go to System > Site Template Styles > Hot HVAC > Style (Tab) > Template Colors. There, you can set up to 6 template colors that can be reused later. After setting the colors and saving the template options, the colors will appear in the color picker palette. So, now, when you, for example, want to change the H1 color, when you click the color picker for the H1, your predefined color(s) will be shown under the palette so you can select them quickly.
Later, after changing a template color in Style (Tab) > Template Colors, it will be changed throughout the template options automatically wherever it's used.
Regards,
Milos
