This one indeed should have 134-A in it from the factory. My recommendation would not be to simply use a single gauge deal from a parts store and try to shove more refrigerant into it. Overcharging is not good for them and doesn't work any better than under charging. It's always good to have two gauges to see low pressure side and high pressure side. If it is significantly undercharged, then the compressor may not kick on due to the pressure switch not being satified. Often it is difficult to get them to take refrigerant if they are in this condition. You can jumper the switch.....but at this point a person ought to be thinking about getting it checked by a professional. I do all sorts of things myself...including air condition charging. But I took some time to educate myself a bit on it. ALL the components on our air conditioning systems can cost quite a bit. Just my thought on it.