Q: 2001 Chevy suburban blowing hot air only in front vents, rear system works fine, also once selector switch is turned on it cannot

The issue with the selector switch is likely electrical in nature. It can be diagnosed along with the non functioning from a/c system problem. Hot air in the front, when you have functioning a/c in the rear, could be due to a blend door malfunction, stuck heater control or, if the vehicle is equipped with separate evaporators, a problem with refrigerant flow or the expansion valve in the front evaporator. To resolve this, the relevant service is an air conditioning system inspection. The responding certified mechanic will come to your location, pinpoint the fault and get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.