What is the Correct Method for Adding Car Refrigerant?
2 Answers
Automobile air conditioning refrigerant, commonly referred to as car refrigerant, is mainly divided into two types in vehicles: environmentally friendly 134a and non-environmentally friendly R12. The correct method for adding car refrigerant is as follows: 1. After evacuating the system, close the high and low pressure manual valves on the manifold pressure gauge. 2. Connect one end of the middle hose to the refrigerant can injection valve fitting: open the refrigerant can valve, then loosen the nut at one end of the manifold pressure gauge hose to allow gas to escape for a few minutes, then tighten the nut. 3. Open the high-pressure side manual valve to the fully open position and invert the refrigerant can. 4. Inject the specified amount of liquid refrigerant from the high-pressure side: close the refrigerant can injection valve and the high-pressure manual valve on the manifold pressure gauge, then remove the gauge. When adding refrigerant to the system from the high-pressure side, the engine should be in a non-starting state, and do not loosen the low-pressure manual valve on the manifold pressure gauge to prevent hydraulic shock.
I've been repairing cars for over a decade, and adding refrigerant must follow proper procedures. First, wear protective gloves and goggles - refrigerant can cause frostbite upon skin contact. Connect the manifold gauge set to the vehicle's low-pressure port, typically marked with a blue or black cap. Evacuating the system is the critical first step: run the vacuum pump for several minutes to remove air and moisture, then verify the vacuum gauge holds steady with no fluctuations. Next, slowly open the refrigerant can valve to allow gradual flow into the system; ideal low-side pressure ranges between 25-40 psi depending on vehicle model and ambient temperature. Adding too quickly risks pressure spikes that can burst hoses. After charging, start the engine with AC at maximum blower speed - cool air output indicates success, while warm air suggests potential leaks or issues like compressor failure. Importantly, use standard R134a refrigerant, not obsolete R12 which can corrode modern systems. Regular AC pressure checks prevent costly repairs, saving both money and headaches.
