What are the specs for AC system?

[Zmanco]

I'm running the dealer installed AC on my 73 with a 81-83 compressor and Freeze 12 refrigerant. I recently picked up a Harbor Freight AC manifold gauge set http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92649 and need to know the specs for pressure on both sides when the system is filled properly. I've searched using just about every combination of words I can think of, but so far nothing. Can anyone help me out?

 

Also, assuming I need to add some more refrigerant, what is the proper procedure to do that? The manifold has a fitting to allow this, but is there a specific sequence? And just to confirm, is it added to the low pressure side?

 

Any other words of advice and/or cautions from those who know AC systems? I know the theory of how they operate, but am without much practical knowledge.

[RTz]

There's no end of opinions on AC systems if you Google... everybody has their own 'right way'.

 

Keep in mind system pressure is subject to ambient temperatures so you'll want to watch out for that trap. Most pro-shops would prefer a full vacuum and reintroducing a known quantity of refrigerant and oil. Gauge's are a great diagnostic tool, but they don't tell you how much refrigerant is in the system, at least not directly.

[Zmanco]

I follow that thinking, but I would imagine that there is a spec (perhaps generic one for this vintage system) for the range of acceptable values for the high and low side pressures. I'm a noob with measuring AC and while I've watched it done, I don't remember what the target values were.