It sounds like you have either a plugged metering orafice or plugged filter dryer.
First of all you need to recover the refrigerent in the system( in the refrigeration trade we are prohibited from venting) then use a vacuum pump to remove all of the non condensables and moisture, then weigh in the correct amount of R134A as specified for your vehicle.
one suggestion is if you do not have all of the equipment for servicing refrigeration systems, it may pay for you to take it to a shop that services ac.
Good luck
Bill
