Why wont my inner heat doesn’t work so well but my back defroster work

The rear window defroster is a totally separate system from the rest of the ventilation system -- because it uses a grid of electrical wires to heat the rear glass in an effort to defrost the window. The rest of the climate control system is operated inside the dashboard, with a series of doors that open and close to direct hot and cold air flow. Weak air can be due to restrictions in the dash, or a blower motor that is not operating properly. Separately, the air conditioning system under the hood may not be generating cold air too. Sounds like some hands on inspections are needed by a local tech near you that knows what to do. www.repairpal.com/repair-shops