Roberto;
This is Peter again.
When you said you changed the filter, do you mean the drier in the seal system?
A vacuum pump? Did you bleed the system of refrigerant and use a vacuum pump for 10 minutes to check for leaks?
Did you recharge the system with the oz. of refrigerant shown on the refrigerator label?
Do you have the 3 hose pressure gage assembly to do the work?
Ok, I am going to assume you have some knowledge of what you are doing.
Assuming, you used the vacuum pump to check for leaks (Vacuum held), and you did not get air into the seal system. Air is detrimental (Harmful in a sealed system).
Attach your pressure gage hose assembly. You will not get the desired cooling if you under charged the system, too much vapor in your high pressure liquid side, or over charged, too much liquid in your low pressure vapor side.
So, lets assume you over charged. Bleed 1/4 psi from the system, wait 20 minutes. Check the frost pattern on the evaporator coil. Observe if the evaporator coil frost pattern increases. If not, bleed another 1/4 PSI from the system and wait 20 minutes. By now the frost pattern should have improved. Repeat this until the evaporator coil has a full frost pattern.
I think you may be over your head on this one and need the help of a certified refrigeration technician. Good luck.