AC performance problem at 213K

[SAEED_KIZZY]

I live in a hot area, I know every AC system leaks some amount of refrigerant each year. During my last trip, I noticed that the AC wasn't cooling enough while I was cruising on the highway. I always thought that when the car runs at high speed, cooling gets better turns out it's not true!
After the trip, I connected scanTool to my car and saw AC parameters, everything checked OK but I noticed something when the car is at idle fans turn on, but not at high speed, only when the refrigerant high side pressure is above 1600kPa fans goes to high speed mode by doing that pressure gos down to 1500kPa and it goes to low speed. When the fans go high cooling on the AC degrades; that's why on the highway AC's cooling performance is worse because it always cools air coming into the AC radiator and cools it down. It's all about pressure.
I don't want to go to the shop to fix the AC performance, so I decided to buy a cheap AC refrigerant recharge kit.

simple instruction to use, but I forgot to read it
So I wasted a lot of it, but some of this refrigerant went to the system, and it worked, temperature in full blast and lowest temp setting went from 12C to 7C
before:

after:

Not much change in refrigerant pressure, but cooler air is coming out of the vents. Interesting, but how?
Another observation is "Evaporator temperature." This parameter, at first, was 4C always after charging, but it became somewhere between 0~4C. Turns out this temperature is the parameter that controls the AC clutch. When below 1 °C compressor clutch is disengaged, and when it goes above 1°C, the clutch turns on again.

I am not an expert in the AC car system, but in my car 95% of times compresure clutch is engaged (when AC on) I do not know this is normal operation of car or not but by adding some refrigent to my car I get 5C better cooling and that's enough for now. This was my experience with the Kizashi AC system.

[Woodie]

Mine seems weak too. I've been wondering if it needs more refrigerant.

[SAEED_KIZZY]

Mine seems weak too. I've been wondering if it needs more refrigerant.

If you never charge your system, you most likely need it. I think I only charged my AC with around 50 grams of R134A at most, which makes 5C better cooling, and over the past two days, it has worked fantastically.
When the car was parked under the sun, only after 1 minute of operation, it blew cold air at full speed, and before it was never that cold(I had to reduce the blower speed to get cold air from the vent)

[KuroNekko]

Interesting notes. In the US, most AC kits come with hoses that have gauges on them. The refill process also often involves gently rocking the can back and forth as you refill and watch the pressure in the gauge. I've never had to refill the Kizashi's AC system but have done so in a few other cars. It makes a big difference for sure. I've also experienced that if you overfill the refrigerant even a little, it can cause the system to not produce cold air. I've had to release a bit of the refrigerant and that got the AC clutch to work properly to produce cold air.

As long as you don't have a leak or failing AC components, the can refill is often a solid solution to getting that AC performance back.