A/C question

I have an 87 r134a retrofit I just replaced the compressor, accumulator and the expansion valve. The system was vacuumed. My question is, I put 4 12oz cans of r134a in and the gauge still reads 25 psi. Do I dare put any more in to try and bring it up to 45 psi? It's not blowing very cold, but that could be because we live in a blast furnace here in Fresno

Thanks,
Neil

Mine took almost qty=5 12 oz cans (3.5lbs) - and sits at about 38psi -- cool enough to notice.