Keep it Cool: Charge It Right
Refrigerant charging might be the least understood practice in the air conditioning industry next to setting airflow. Although there are several methods, typically there is only one correct method for the type of unit you are working on. Information contained here is for formally trained EPA Section 608 certified technicians.
Start with the basics for all systems:
- Makes sure the system been properly installed and evacuated. A proper evacuation is critical to proper performance. Need help with this process go HERE!
- Clean the filters and the coils. You cannot charge or check the charge on a system with dirty coils, filters, or blower. The condenser and the evaporator must be clean. The blower must be capable of moving the correct amount of air. Visual inspection of the evaporator can be aided with the use of a video scope by removing the high limit of most furnaces and fishing the shaft up through the heat exchanger to the bottom side of the coil.
- Set the required airflow. You cannot charge a system without correct airflow. After the system is confirmed clean, the airflow must be set to the manufactures recommended settings. Typically this is 400 CFM/Ton +/- 10% Need additional help with airflow go HERE!
- Identify the type of metering device. You need to know what type of metering device the system has as this may determine how the system will be charged. (See photo below.)
- Before installing your gauges, vent the hoses and the manifold with virgin refrigerant (The same type as the system.) to avoid the introduction of air into the system.
- Blends like R410a or 404a must be added to a system as a liquid. Pure refrigerants like R22 can be added in liquid or vapor states. If adding liquid into the suction like, throttle it in slowly to avoid slugging the compressor or diluting and washing out the compressor oil.
- After the charge has been set, avoid installing the gauges as part of regular service. The system should be sealed. Keep it that way!
For more in-depth information, check out the original article at TruTech Tools.
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