Yesterday I installed a compressor and filled it with R134a gas (two 340g cans) and I feel that it does not cool well, and the compressor does not turn off, what could it be? It's a 91 Camaro with a 3.1 engine.

 

If that's all you did.....so many things could be wrong. The amount of refrigerant doesn't matter, it's how much the system requires. What other components did you replace? What readings did the gauges say? Did you pull vacuum?

 

first clean the entire air conditioning system to remove all the old oil from the r12, install a new accumulator, check for freon leaks, the compressor is remanufactured, in the high pressure line has a sensor and the compressor has another, but I do not know what functions they have, I was told that the compressor is not turned off because the lines do not reach the temperature, also because it lacks gas as the blower says it requires 2.25lb.

 

I don't understand what you mean. I'll let the A/C specialist chime in here.

 

first clean the entire air conditioning system to remove all the old oil from the r12, install a new accumulator, check for freon leaks, the compressor is remanufactured, in the high pressure line has a sensor and the compressor has another, but I do not know what functions they have, I was told that the compressor is not turned off because the lines do not reach the temperature, also because it lacks gas as the blower says it requires 2.25lb.

 

2.25lbs is for R12.
R-134a is a different amount which is closer to 1.75lbs if I recall. There are r12 to r134a conversion charts online that will let you know the exact amount.
So at the moment you might actually be slightly overcharged.

First question, did you pull vacuum on the system and the fill it under a vacuum state?
Second question, you say it does not cool well, how cold is the temp coming from the vents?
Third question did you replace the orfice tube and if so what color did you replace it with?
Fourth question did you replace the condenser with a parallel flow one?

 

If I did the vacuum, the system has no leaks and filled it in vacuum, do not replace the condenser is the original and the orfice tube is white.

Yesterday I investigated a little more, how the mechanic filled the system and it turns out that they filled the high pressure system and the low pressure system, I do not know if it affects if the high pressure line was filled.

 

Lots of info in here if you care to study. https://www.thirdgen.org/forums/cool...sion-here.html