Why does rear heater in a 2003 Tahoe blow cold air while front heater blows hot air?

The rear heater in a 2003 Tahoe blowing cold air while the front heater blows hot air could be due to several reasons. Common issues include low coolant levels, a malfunctioning rear heater core, or a problem with the controls that regulate the rear heating system. Additionally, a clogged rear heater core or an airlock in the coolant system might prevent hot coolant from reaching the rear heater. Checking coolant levels and inspecting the rear heating system components is advisable to diagnose the issue accurately.