Here's why you should strongly consider a professional:
* Vacuuming the System: Before adding refrigerant, the system must be completely evacuated of air and moisture. This requires a vacuum pump capable of pulling a deep vacuum. Moisture in the system can severely damage the compressor.
* Identifying Leaks: If your AC system is low on refrigerant, there's a leak somewhere. Finding and fixing the leak is crucial; otherwise, you'll just keep recharging and wasting refrigerant. This often requires specialized leak detection equipment.
* Refrigerant Type and Amount: Using the incorrect type or amount of refrigerant can damage the compressor and other components. The correct type and charge amount are specified for your vehicle's year and model.
* Safety: AC refrigerant (R-134a) is under high pressure and can cause serious injury if mishandled.
If you decide to attempt it yourself (at your own risk):
1. Gather the necessary tools and equipment: This includes a manifold gauge set with hoses, a vacuum pump, a refrigerant recovery/charging machine (capable of handling R-134a), the correct type and amount of refrigerant (check your owner's manual), and leak detection equipment (dye or electronic).
2. Consult a repair manual: A Haynes or Chilton manual specific to your 1999 Pontiac Sunfire will provide diagrams and instructions.
3. Follow the instructions carefully: The process involves recovering existing refrigerant (if any), vacuuming the system, checking for leaks, and then charging the system with the correct amount of refrigerant.
4. Observe safety precautions: Wear safety glasses and gloves. Work in a well-ventilated area.
Recommendation: Take your 1999 Pontiac Sunfire to a qualified automotive technician or AC specialist. The cost of professional service is far less than the potential cost of damaging your AC system by attempting a DIY recharge without the proper knowledge and equipment. They have the tools and expertise to diagnose and fix the problem correctly and safely.
