Running a system check can determine whether that’s the case. Answer. Most refrigerant blends boil at different rates and require complete evacuation before adding a full charge. These two devices note dividing points between the high pressure and low pressure, or simply high side and low side of the refrigeration system. The problem is the low and high side gauge readings will stay fairly constant from a half pound under-charge to a half pound over-charge. When charging liquid refrigerant to the high side of the system, do u have to flip the refrigerant cylinder upside down - Answered by a verified HVAC Technician. Checking the pressures, both high side and low side were low. [Note that if you want to charge the system on the low side using vapor only, you can safely do so using a refrigerant vaporizer attachment instead of heat to assure that no liquid goes where it's not wanted.] Step 2: Restart the engine and turn on the air conditioning. Keep in mind that if you had to add refrigerant, the old refrigerant had to escape somehow, and if you didn't find the leak, the new stuff will go out the same way. On an all refrigerator, the low side pressure could be around 15 - 20 psig. The high and low sides on a home A/C compressor are also known as its discharge and suction lines. The system is filled partially with liquid and partially with vapor. How can you tell when a system is low on refrigerant? The amount of refrigerant will be stamped on the model and serial tag. ... (low pressure) side do not match the manufacturer’s recommended specifications. The high side fitting is located between the AC compressor and condenser. Do you need to Charge an AC Unit with Refrigerant? If it starts to frost further. The compressor accomplishes this task by creating high and low pressure areas with the use of a moving piston in a sealed chamber. This is not the case with so R-410, which is considered a near-azeotrope, using compounds that boil at almost the same rate. They allow the same refrigerant, which evaporates at 40F condense at 120F. This will let you add a measured refrigerant charge to the low side of the system while still making an accurate measurement of the refrigerant measured in ounces. equal to outdoor ambient). If you can identify one of the valves, you have identified the other. While recharging the system with refrigerant, the 134A manifold gauge pressure should be monitored so the proper amount of refrigerant is used. Compressor takes refrigerant gas at low pressure and temperature (about 40F) and compresses it. Two pounds of R-22 later, the low side came up to normal but the high side was still low (S.P. Obstructions. The compressor accomplishes this task by creating high and low pressure areas with the use of a moving piston in a sealed chamber. That's where you hook up the hose. The low side is in the hose that runs from the evaporator to the compressor, this is called the suction side, because the compressor is sucking out the freon from the evaporator. An azeotrope refrigerant blends multiple refrigerant compounds to form a single refrigerant. A home A/C compressor is the engine that keeps coolant circulating through an air conditioning system. You do not need to add any oil. 90 psi on the high side is low and indicates low charge, but I am not good at judging performance based on gauge readings. ONLY use the suction side to add freon or you will damage your compressor, as a liquid is non-compressible.