Where is the heater valve on a 1993 Buick Roadmaster limited 5.7 liter?

The heater valve on a 1993 Buick Roadmaster Limited 5.7L is located underneath the dash, on the passenger side. It's not easily accessible and usually requires partial or complete disassembly of the dash to reach. It's often a tricky job. You'll likely need a shop manual to guide you through the process, as access varies slightly depending on specific trim level and options.