AC blowing cold up front ,rear blowing warm air. Are they separate systems?

The rear utilizes the same compressor and refrigerant system, but does utilize additional lines to a rear "auxiliary" evaporator core. When the A/C is running, the rear core gets cold too. Then it's about the fan blowing and giving out the cold air through the vents -- as long as the temperature blending controls in then back are also working. Testing hands on is needed. www.repairpal.com/repair-shops