Evacuating the System

Evacuating the System
This process, the removal of unwanted air and moisture, is critical to the correct operation of the air conditioning system.

Moisture in the system can be highly destructive and may cause internal blockages due to freezing; water suspended in the lubricating oil will damage the compressor. Once the system has been dismantled, or the refrigerant charge recovered, all traces of moisture must be removed before recharging.

Specific procedures will vary depending on the individual characteristics of the recovery/recycle/recharge equipment, and must be carried out exactly in accordance with the manufacturers instructions. However, it is recommended that initially only the high-side valve be opened at the start of the procedure. After a short time a small depression should be seen on the low-side, at which point the low-side valve may be opened and the evacuation process completed. If a vacuum is not registered on the low-side, it may indicate that the expansion valve is permanently closed or that the system is blocked. This simple check may save time and effort when the system is recharged.