Our ever expanding list of articles on HVAC/R products and processes will help you get more performance out of your tools, and more time out of your day. The Evacuation and Charge Process A vacuum pump is used to remove air and contaminants from an HVAC system, creating a vacuum state. It is important to note that a vacuum pump is not a recovery unit. A recovery unit should always be used to make sure the refrigerant is recovered from the system before you begin the vacuum process. A vacuum can help protect your system from contaminants and non-condensable gases, which can damage HVAC system components, reduce system efficiency and even cause failure. A vacuum pump “pulls” air, moisture and contaminants out of the system after it has been repaired and before it is recharged. The deeper and more complete the vacuum, the more contaminants trapped within the system components and even in the compressor oil are removed. Prior to pulling a vacuum and charging an HVAC system, you’ll want to recover, repair and check for leaks.

Assuming that these items have been checked off your list, you’re ready to safely evacuate. Before starting, fill the vacuum pump with vacuum oil. Remove the cap, open the fitting and begin pouring. Keep pouring the oil until the oil level reaches the oil line. Here you’ll benefit from a large oil fill port and sight glass, which gives you the benefit of being able to see when the oil reaches the appropriate level. It is important to note here that the quality of your vacuum pump performance is directly related to the quality of your vacuum pump oil. The cleaner your oil, the better your pump’s performance. We recommend high vacuum mineral-based oil be used in all pumps regardless of the type of oil that is used in the system. Once you can see through your sight glass that you’ve reached the proper oil level, put the fittings back on, or, if desired, attach the exhaust filter. Remove the Schrader cores (if present) with the core removal tools. Install the test and charging manifold.

Connect the hoses from the manifold to the system.  Connect the low side (or blue hose) to the low side core removal tool and high side (or red hose) to the high side core removal tool. If you’re using a four-valve manifold, connect the 3/8” hose from the vacuum port on your manifold to the 3/8” port on the vacuum pump. outside air conditioner units for saleConnect the 4th hose from the manifold to the refrigerant cylinder.how to choose a central air conditioner unit If you are using an extension cord, make sure you are using the proper gauge for your pump.air conditioning units for the home Plug in the power cord for the pump. Open all manifold valves and make sure the vacuum valve and core removal tool ball valves are open.

For cold weather starts, open the intake port until the pump reaches running speed and then close it off. You are now pulling a vacuum. It is important that the oil level remain steady when the pump is running for proper operation – about 1/2 to 5/8 up in the sight glass. If it falls too low, the vacuum pump could be damaged. If it’s too high, it will increase the oil in the exhaust. Once you have pulled a vacuum that meets the manufacturer’s specifications, you can close the valves on the core removal tools. Observe the vacuum gauge. It is normal operation for a rise in microns to occur. However, if the rise continues to atmosphere (760,000 microns), there is a leak in the system. Check the system manufacturer’s recommendation for tolerance. Once you are satisfied with the reading, close the valve that connects the manifold to the pump. You can now shut off and disconnect the vacuum pump. Your evacuation process is complete and you are ready for system charge.

To charge, open the valve on the refrigerant cylinder. Add enough refrigerant to create a small positive pressure in the system – about 3 psi on the low side. Remove the digital vacuum gauge and complete the charging process per the manufacturer’s specifications. Once the charge is complete, you can replace the valve cores and remove the vacuum valve and core removal tools. It’s a good idea to simply replace Schrader valves, as they are not that expensive and new valves will reduce the likelihood of system leaks. Screw them back in and seat them properly. Remove your tools and you are ready to go. Connect a digital vacuum gauge for accurate vacuum measurement. The best place to measure vacuum is at the system, not at the pump. With a combination vacuum and charging valve on your core removal tool, you can attach the electronic vacuum gauge directly to the system and isolate it from the pump, hoses and manifold for a true indication of the vacuum in the system.

If you suspect an open or wet system, be sure to use the gas ballast feature on your vacuum pump. The gas ballast prevents water vapor from condensing in the vacuum pump oil by introducing a small amount of fresh air into the pumping chamber. Open the gas ballast just slightly and then begin to watch your electronic vacuum gauge. If the vacuum stays at a consistently high level of microns or doesn’t pull down below 5,000 microns, your system still contains contamination or has a leak. Repair the leak before proceeding. A way to speed the vacuum process is to use a heat gun. This warms the molecules and gets them to leave the surface sooner, speeding the flow of vapor molecules to the pump. Remember to be careful because they do get hot and will take paint off systems.There are ways of how to recharge air conditioner systems. The methods for this air conditioning maintenance are,refrigerant charging from high pressure side,refrigerant charging from low pressure side,and refrigerant charging using weight

Here are some extra tips for you before venturing into how to recharge air conditioner.purpose of refrigerant charging is to add or remove, a specified amount of refrigerant from an air conditioning system, such that you will get comfort air from the air conditioner.contrary to popular belief, refrigerant do not require periodical charging. It is not a consumable item within an air conditioning unit, unless,there is a leak within the system,you have just changed an air conditioner part, ORyou are assembling a brand new air conditioner unitrefrigerant of 4xx series, e.g. R-404a are non azeotrope type refrigerants, EXCEPT for R-410.R-410 is a near azeotrope mixture.So, what’s the big deal between azeotrope and non azeotrope refrigerant?Azeotrope refrigerants consist of more than one blend of refrigerants, but it acts like a single refrigerant.Non azeotrope refrigerants on the other hand, DO NOT act like a single refrigerant.The implication is that, the blends will be lost from the system at different proportions due to different boiling temperatures, whenever there is a leakage in the non azeotrope refrigerant.

Hence, charging of non azeotrope refrigerant can only be carried out from zero to full. Never top up this type of refrigerant in case of leakage.Evacuate, and fill to adequate quantity.Azeotrope, or near azeotrope blends will act as a single refrigerant, and therefore, may be topped up in case of refrigerant leakagedo not overcharge as this will cause compressor damage,do not underchargecorrect problems within the system, if subcooling or superheat is inadequate, even if the pressure in the system has reached design statenever use open flame to heat up refrigerant cylinders. Use warm water insteadrecover the excess refrigerant into recovery cylinder, if the system is overchargedA little more before we go further into how to recharge air conditioner systems. the amount of refrigerant superheat is about 10 oF (5.5 oC), or as per manufacturer’s recommendation, ORthe amount of refrigerant subcooling is about 10 oF (5.5 oC), or as per manufacturer’s recommendation, ORthe sight glass after (or on) the filter dryer is clear after charging.

Presence of bubbles means that there is no adequate chargingIt’s about time we look into details of "How to Recharge Air Conditioner". How to recharge air conditioner style 1: From high side: This method is best used with capillary tube fitted systems.Other criteria that will require this technique are inadequate subcooling, and to top up refrigerant.First,stop the compressor,know the refrigerant in the system, and get the correct refrigerant to be charged,attach the refrigerant cylinder or canister to the centre manifold’s hose of the pressure gauge set,purge the line by throttling the plain gauge’s regulator, and the refrigerant cylinder’s regulator.Don’t forget to close the regulators after purging,attach plain pressure gauge’s hose of the gauge set, to the liquid line service valve of the air conditioning unit.Make sure that the protective cap of the service valve is taken outopen the plain gauge’s regulator slightly,throttle the refrigerant cylinder’s regulator,close the cylinder’s regulator when the pressure in the high pressure side reaches the design operating pressure,operate the air conditioning unit,check the subcooling, and make sure that the is clear,stop the air conditioning unit if the subcooling is inadequate.

Repeat steps (7) to (10) until the charging is adequateCourtesy for condenser picture: Bryant Air Conditioners How to recharge air conditioner style 2: From low side: This method is with thermostatic expansion valve fitted systems.Other criteria that will require this technique are inadequate superheat, and to top up refrigerant.First,stop the compressor,know the refrigerant in the system, and get the correct refrigerant to be charged,attach the refrigerant cylinder or canister to the centre manifold’s hose of the pressure gauge set,purge the line by throttling the compound gauge’s regulator, and the refrigerant cylinder’s regulator.Don’t forget to close the regulators after purging,attach compound pressure gauge’s hose of the gauge set, to the suction service valve of the air conditioning unit.Make sure that the protective cap of the service valve is taken outopen the compound gauge’s regulator slightly,throttle the refrigerant cylinder’s regulator.The pressure within the system shall be less than the condensing pressure of the refrigerantoperate the air conditioning unit,close the cylinder’s regulator when the pressure in the low pressure side reaches the design operating pressure,the charge should be adequate once the design pressure on the low side is reached, but it is good to check the superheat, and make sure that the sight glass is clearCourtesy for condenser picture

: Bryant Air Conditioners How to recharge air conditioner style 3: Using weight: This method is used to charge refrigerant to an evacuated, or newly assembled, and moisture removed air conditioning unit.The steps,stop the compressor,know the refrigerant to be handled by the system, and get the correct refrigerant to be charged,attach the refrigerant cylinder or canister to the centre manifold’s hose of the pressure gauge set,purge the line by throttling the compound gauge’s regulator, and the refrigerant cylinder’s regulator.Make sure that the protective cap of the service valve is taken output the cylinder on weighing scale,ORget adequate number of refrigerant canisters to charge the system open the compound gauge’s regulator slightly,throttle the refrigerant cylinder’s regulator,operate the air conditioning unit,close the cylinder’s regulator when the correct amount of refrigerant is added to the systemcheck the superheat, operating pressure, and make sure that the is clearCourtesy for condenser picture: Bryant Air ConditionersThat’s about it on how to recharge air conditioner systems.