Air Conditioner problems of the 2001 Chevrolet Suburban

Transmission has not been shifting correctly for a long time. Became very noticeable in July of 2001. Rear air sometimes does not turn off when ignition is off. Front airs sometimes cuts self off and begins to blow warm air. Although not applicable. The dealership has changed out front and middle seat covers from cracking problem I talked with gm and they advised the dealership to correct these since I do still have a warranty. I am still unsatisfied with the performance of my vehicle. This is the 3rd Suburban I have owned. The other 2 were GMC's. I never had a problem of this nature before. This one has been annoying with small problems since day one! dt.