recharging the a/c system.

I have a 99 leganza, and one day the air went out, So I am trying the recharge the system by putting refrigerant in. I hooked up the can to the hose, and then the hose to the a/c line. and turned the air on full blast. I then turned the screw to puncture the refrigerant can, and nothing happens. The refrigerant is not going into the system. I dont know why. any suggestions or comments?

Also, wich a/c line is the low pressure? the line on top or bottom? thanks.

I believe it is the top hose but I havent loooked in awhile. The low side hose is large and I dont think the fitting for filling will fit on the high side so you probably have it right. You have to puncture the can and then screw the valve back up to allow refrigerant to flow in.

If the refrigerant went out all at once you probably have a bad seal that will have to be replaced.If it leaked down slow you might be okay. Once atmospheric gasses have gotten into the system you must pump the system out with a vacuum pump.