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What is Refrigerant Charging?

By Paul Scott
Updated May 17, 2024
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All air conditioners and refrigerators rely on the correct charge, or amount of refrigerant gas in their systems, to work correctly. Refrigerant charging refers to the replenishment of these gases when system repairs or leaks have caused depleted levels. Refrigerant charging may be carried out using bulk refrigerant containers or charging kits which generally only hold enough gas for one charge. In either case, a refrigerant charging manifold with its associated hoses, valves, and gauges is needed to complete the operation. Recharging of refrigerant gas is typically carried out via a non-return service port or valve fitted to the system.

Air conditioning units and refrigerators are designed to operate correctly with a predetermined charge of refrigerant gas. Under perfect operational conditions, air conditioners and refrigerators would never require recharging but leaks do sometimes develop which deplete refrigerant charges. Repairs to these systems also require the draining and subsequent recharging of the refrigerant. There are several quick pointers during normal operation which indicate a depleted refrigerant charge. These include low system efficiency, noticeably lower temperatures from the condenser fan, icing up of the coils, and localized oily residue on pipes which may indicate a leak.

If a depleted refrigerant charge is suspected, the condition should be verified using a set of system pressure gauges; this verification procedure may have to be carried out by a qualified technician. If the result is positive, the system should be recharged as soon as possible because low refrigerant charges place excessive loads on the compressor. Most refrigeration and air conditioning systems will feature a service valve to facilitate recharging the system. These valves are typically of a Schraeder non-return design which allow for refrigerant charging without any loss of system pressure. The recharging process is carried out from a cylinder or recharge kit of relevant refrigerant via the manifold and gauge assembly.

Refrigerant charging is carried out with the compressor running to ensure even charging. The system should also be given time to warm up to normal operational temperatures before recharging commences. When recharging, refrigerant gas should be added in small increments to avoid overloading the system. Between each gas input, the system should be allowed to run for a short time to allow the gas charge to settle and the pressure checked. When the pressure is within the manufacturers operation specifications, the supply valve on the cylinder can be closed and the manifold removed from the system.

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Discussion Comments
By rugbygirl — On Jul 14, 2011

@MissDaphne - It's certainly possible, but only a mechanic could tell you for sure. Has it always been that temperature, or has it been warming up lately? Getting less cold over time indicates a leak or a need for recharging a lot more than if it's never been very cold.

I drive an older car myself. (Just turned 12! If it was a person, it would be middle school!) The AC doesn't blow very cold and I have the same problem--the car just never cools off. But I had it checked out and they said the refrigerant level were fine. It's just not very good air conditioning!

By MissDaphne — On Jul 13, 2011

The AC in my car doesn't blow very cold. Could it be that the refrigeration system needs to be charged? My poor baby is just so sweaty every time I get him out of the car. It blows cool, but not cold, and on a really hot day, it just never does get at all cool in the car.

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