What should be done with an A/C system before recharging it with refrigerant?

Before recharging an A/C system with refrigerant, it is essential to use a vacuum pump to evacuate it. This step serves multiple important functions. First, evacuating the system removes any moisture and air that may have entered the A/C system. Moisture in the system can lead to acid formation, which can cause significant damage to the compressor and other components, leading to costly repairs.

Second, creating a vacuum helps ensure that the refrigerant will properly fill the system and circulate effectively, which is vital for the A/C system to function correctly. This process can also help identify any potential leaks. If the vacuum does not hold (meaning the vacuum gauge shows a rise in pressure), it indicates that there may be a leak in the system that needs to be addressed before recharging.

The other options are relevant to specific maintenance tasks but do not constitute the necessary procedure before recharging. For instance, filling the system with oil can be important, especially if the compressor has been replaced, but it doesn’t substitute the need to evacuate moisture and air. Leaving the system as is would allow any contaminants to remain, which can impair functionality. While testing for leaks is also an essential practice, it typically follows the evacuation process to confirm that the