Home Central Air Unit has No Freon Recharge Valve

My home central air unit was not producing any cold air, so I called someone in to look at it. The unit is an Armstrong 38HWC182A. The technician said it had a low freon level. He also said the unit had no recharge valve, and that he would have to install one in order to recharge it.

Is this normal? That is, an A/C unit with no recharge valve.