a/c blows cold and then warm, when climbing a hill blows warm only

Several possibilities here. Your car has a sensor that monitors the position of your throttle (gas pedal position). One of its purposes is to shut off the air conditioning compressor when your under "wide open throttle" ie: getting on the freeway, passing a vehicle, or going up a hill. This allows your car to have maximum power. After you release the pedal the air should come back on cold again. We could perform a position test on that sensor to verify its staying in range. Rob Ocello - Ocello's Automotive Center