My AC stopped working. I decided to evac the system and put in new freon. after you vacuum the system and letting it sit for 2 hours there was no leaks. However, as soon as I turn the AC on and before I even started adding the free on the compressor was on.
After an hour of putting in 12 oz of freon, the fans never turned on as they should with the AC. I gave up after putting in 15 total ounces, 21 Oz is the recommended. It took me an hour and a half just to put in 15 oz. also there was only 20 lb differential between the high and the low.
Why did u evac? You seem to think nothing was wrong? Why not add a bit?
You evac. And then fill into an empty system. With compressor/motor off. I always get at least 12oz in before I even start motor.
Initially, with the engine off, you could have opened the high side port with the can inverted and dumped liquid into the condenser. Once the pressure between the can and car equalized the high side port must be closed and the low side opened with the can upright start the engine and continue charging while shaking the can or holding it near the radiator to heat the refrigerant. Professional equipment measures the specified amount and heats it to quickly force it into the system. Variable displacement compressors make things complicated.