So it's getting to be that time of year. The time of year in Phoenix where it starts to get really really hot. So it's time to get my AC running. When i bought the car, the owner told me that it just needed to be recharged. After further inspection (and after I bought the car) I discovered a rather large hole in the hose from the compressor to the evaporator. My thoughts were that I would just need to disconnect the hose from the compressor and the evaporator under the dash and replace it. One thing I also noticed is that there is no dust cap for recharging. Is this stock or an aftermarket change? I was also told that I could just add 134a in the r12 system and it would'nt hurt anything. Im not sure how true this is. If anyone has information in detail for going about this type of thing, it would very very much appreciated. Phoenix is HELL in the summer.

So this is a whole new topic, and not very Datsun-specific.

B310 has factory airconditioning. But if your dashboard has odd controls (heat separate from cool) and the A/C vents are below, not part of the heater vents, then it probably is aftermarket.

You generally either need to replace the evaporator or have it purged before recharging the system. I suspect the experts in Phoenix know more about it. Maybe the air is dry enough there to not worry about it.

Hi I am an air con and refrigeration mechanic and thought I could offer a bit of help, you can change from R12 to 134a refrigerant with minimal hassles just need to remove the oil from the system by flushing it out until it is all clean then it's just a matter of having a new drier/filter installed, the new hose installed and then having the system vacuum tested over no shorter than 4 hours to remove any traces of water/condensation. Once all is ok it is time to recharge the system with the new 134a gas and compatible oil for your system, should only take 5.5hrs to do the job professionally not hard to do just a matter of checking pressures while testing to make sure the system is charged to the right level, too much gas and it will flood back to the compressor and hydraulic not enough gas and the liquid line from the condensor to the evaporator/TX valve will not fill with liquid refrigerant/oil mix and you won't be getting the most out of the system.
Never believe someone if they say "the air con just needs a regas!" air con systems never need a regas they just leak and then require the leak to be repaired and then regassed it's like most people think that the gas goes bad or something hope thats of some help any other questions just ask

Thanks for the input, that helps a lot. Is there a way to fill the system with gas if it doesnt have a dust cap on the main hose or would I have to buy a hose that is already fitted with one? Im not so sure how it works.