What are the steps for adding refrigerant from the low-pressure side?
3 Answers
The steps for adding refrigerant from the low-pressure side are: 1. Connect the manifold pressure gauge to the compressor and refrigerant canister, then use the low-pressure manual valve on the manifold pressure gauge to add gaseous refrigerant to the low-pressure side of the refrigeration system; 2. Open the refrigerant canister and loosen the nut on the middle injection hose connected to the manifold pressure gauge until you hear the sound of refrigerant vapor flowing, then tighten the nut to remove air from the injection hose; 3. Keep the refrigerant canister upright, fully open the low-pressure manual valve, and inject refrigerant from the low-pressure side. When the system pressure reaches 0.4MPa, close the low-pressure manual valve; 4. Start the engine, turn on the air conditioning switch, and set both the blower switch and temperature control switch to maximum; 5. Open the manual valve on the manifold pressure gauge to allow refrigerant to continue entering the refrigeration system until the filling amount reaches the specified value; 6. After filling is complete, close the low-pressure manual valve on the air conditioning pressure gauge, shut off the injection valve on the refrigerant canister, stop the engine, and remove the air conditioning pressure gauge.
When adding refrigerant to the car's air conditioning system, I always operate through the low-pressure side to ensure safety, as adding from the high-pressure side can cause a sudden pressure surge that damages the compressor. Here are the steps: First, prepare the manifold pressure gauge and refrigerant canister; start the engine and run the air conditioning in maximum cooling mode to activate the compressor; then connect the gauge to the low-pressure port, which is usually marked with an 'L' or has a blue cap; slowly open the valve to add refrigerant while closely monitoring the pressure gauge readings, keeping it between 25 to 40 PSI, and avoid adding too quickly to prevent refrigerant backflow or overpressure; after filling, close the valve, disconnect the connections, and check the system for leaks. I've seen cases where adding too hastily caused pipe ruptures, leading to repair costs in the tens of thousands. Doing this regularly can prevent sudden air conditioning failures, especially giving peace of mind when driving in hot seasons.
I had a lot of fun DIYing refrigerant recharge, and the low-pressure side method is simple and practical. Preparations include parking on level ground with the engine idling and the AC on max; connecting the pressure gauge to the low-pressure port and slowly releasing the refrigerant from the can—don’t rush. While adding, keep an eye on the pressure, maintaining around 30 PSI without exceeding it, or the compressor will make noise. It’s a huge money-saver—shops charge hundreds, but DIY costs just a few bucks. However, remember to wear gloves for protection, as refrigerant contact with skin is very cold and can also pollute the environment. After finishing, tighten all valves and clean your tools. Don’t forget to check if the O-rings are aged or cracked, otherwise, leaks will waste material. Occasionally fixing these small issues myself boosts my confidence in vehicle management and helps me learn basic mechanical knowledge to avoid being scammed.
