Crank your engine and turn the AC on high cool, high fan. If your recharging hose is equipped with a pressure gauge, check it to determine if the system needs refrigerant. If the pressure holds steady in the recommended range, the system is full and should not be charged.
The driving distance between Dallas, TX and McKinney, TX is 32 miles. The driving time would be approximately 35 minutes if driving non-stop in good conditions. (The driving time does not take into consideration conditions such as weather, road work and rush hour traffic in urban areas.).
The total driving distance from San Antonio, TX to McKinney, TX is 306 miles or 492 kilometers. Your trip begins in San Antonio, Texas.