Pablo1987, did you check with both AC gauges to see if the high side is reading too high as well the AC system short cycling? This would point to the expansion valve not operating properly, stuck partically closed and failing. They are cheap while system is opened up.
As with any AC system unless being rather new is to change out the expansion valve with the dryer once the system has been opened and exposed to the air.
On adding more R134a, that's a guessing game the proper amount as it takes very little to be under or over charged each resulting in reduced cooling. R134 has a narrow range between under and over charged systems vs ye "ol R12 which you can be under and over charged by a wider amount and still have good cooling.
Someone mentioned recharge with sealant in it, that's ok if you planned on selling the vehicle right away a patch fix. Must mention most AC shops will not touch a vehicle that has that crap in it as it will damage their recovery system with you getting a $2 to $3K repair bill on their recovery machine.
Best way to vacuum down, wait 3/4 to 1 hr. checking for any leaks before charging the system again. This time the weighed amount required no guessing games.
Even static pressure to tempature charts will not show the amount still in they system and only pressute to temp readings. Auto parts store AC items for the public a money maker.
For under $450 you can purchase a TWO STAGE vacuum pump not a cheaper SINGLE STAGE pump, talking a 5 cfm pump of 1/2 hp not those weak toy units.
A three hose two gauge (low & high) gauge set just under $80 unless you must have a YELLOW JACKET $265 gauge set. Your daily AC job then splurge.
Advice, get a three hose gauge set and add a Tee fitting allowing four houses to the gauge set.
One hose to evacuate, one to charge, one for the low side and one the high side AC system connections.
Weigh each 12 oz. can as they are not all filled equally, deduct can tare weight plus add 2 oz. remaining in the hoses in the gauge set. Weigh in the vehicle AC spec amount period! 1
Strsight R134a in 12 oz. cans with the PROPER FITTINGs, 12 oz. to charge hose that has a shutoff valve adapter vs them parts store "El Chespo's that will bleed off your refrigerant while swaping out cans. There goes your refrigerant as well the weight amount measured.
Before charging time and before evacuating the system it's also a good time to add a litte UV dye additive for future should you develope a AC system leak, easy to locate the problem.
If your really lucky and have a friend in the AC business that use 30 pound containers of R134a, Walmart has it for $139.99 last checked vs 12 oz. cans. Way cheaper working with 30 lb. containers tan 12 oz. cans.
Between two 30 lb. containers of R134a plus three 30 lb. R12 i'm set able to charge my personal vehicles requiring both refrigerants.
Two Ford Escapes (04 & 10) one had a leaking condenser, one 81 Delorean, one 68 Ford F250 pickup plus a 97 528i BMW that a rock punctured the condenser.
Low on R134a in the 95 Disco after 26 years from date of manufacture use pulling a vaccum check then recharging by weight amount, it blows 37-38*F on a 78*F day at a constant 37 mph speed. DIY evac test and recharge alone with the disco more than paid for the equipment.
Most parts including OEM besides cheaper and lower quality replacement parts from autohausaz.com. Several times they have beat others in pricing including OEM replacement parts.
Kozyvacu TA500 two stage 5 cfm vacuum pump that will vac down to 50 microns, way lower than required for clunky automotive AC systems. Recall $189 last spring purchase.
DIY way cheaper saving myself thousands of dollars plus I own the equipment for future AC repair and recharge jobs.......~~=o&o>......