Driving in the heat of summer with a malfunctioning car air conditioner can be brutal. Before you take your car to the shop for a costly repair, check a few of these things out to see if you can't take care of the problem yourself. Make sure that the refrigerant hasn't leaked out. Check your local auto supply store for a product that can be added to the system to check for leaks. Check the pressure level in your air conditioning system as well. Look for malfunctioning fuses, switches, or wires. Broken fan belts can also cause air conditioning malfunctions. If you have ruled out all of these possible causes, it may be time to call a professional.