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Topping up the refrigerant

Gas needs to be charged in a fridge system only if the system is under charged. 

The safest and quickest method of adding refrigerant to a refrigeration system is to add the refrigerant through the charging valve as a liquid.

A refrigeration system should not be charged if there are leaks or if there is reason to believe that there is a leak in the system.

 The leaks must be found and corrected. 

A system should be checked for leaks immediately following, or during the process of charging.

Freon bottle needs to be weighed before and after charging gas to ascertain the quantity of gas charged.

A charging connection is fitted in way off the filter dryer.  This allows additional refrigerant to be introduced into the system via the dryer element.

The normal procedure is to shut the condenser liquid outlet valve. The compressor is now sucking from the system and delivering to the condenser where the gas liquefies and the liquid level begins to rise in the reservoir. 

The Freon gas bottle is now connected via a charging hose to the charging connection on the filter dryer, the air from the charging hose is purged by opening the gas bottle valve and then the hose union is tightened on the charging connection. 

The liquid valve on the gas bottle is opened and the compressor started, as the only gas entering the system is now coming from the charging line the compressor will suck this gas and send it to the condenser where it is liquefied, while the charging is on the refrigerant liquid level in the condenser is monitored, the charging is stopped when normal level in the condenser is achieved. 

The charging connection valve is now closed, the gas bottle outlet valve is closed the charging hose is removed and the condenser liquid line outlet valve is opened and compressor started.


  1. Great blog, thanks for explaining the steps to top up the refrigerant gas. Looking for more interesting blogs! R744 gas


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