A/C recharge question
 

So the A/C doesnt feel as cool as my other car so I want to attempt to recharge it as everyone says its not that big a deal. I couldnt find any how to info on this in the FAQ.
Anyone know exactly how to do this?
AND
There are a million A/C recharge kits out there. Can anyone recommend a good one.
THanks

if you have a low charge, it means you have a leak. a leak that needs to be fixed.

whats your 'other car'?

and whats the air discharge temp at the center duct?
this should be measured at 2000 rpm, highest can speed, coolest temp setting, mode on vent, and on recirc.

be sure to note the ambient temp and humidity also. if you dont have that equipment, punch your zip into weather.com

find the low pressure pipe (marked with L, i think its a green cap and somewhere on the very top), start engine, run ac, get a gauge, check pressure.. if low, add gas. this may take a while depending on the pressure of the filling canister. i mean it, takes a while at times.

There is so much more to diagnosing & repairing an air conditioning system than simply topping off the refrigerant charge. You must use a set of gages to read both the high and low side pressures while it is running. You must have a point of reference to begin your diagnosis, not merely saying it "needs a recharge". Poor AC performance can be caused by a number of things, so accurately monitoring the pressures and feeling the temps of the high and low side lines can go a long way in determining the exact problem with the system.

Case in point: I have seen several 95-99 Maximas that have needed a new compressor because of internal seal failure. Customer complains of warm air through the vents, compressor is turning, so you would think that it just needs a recharge or topping off, yes?

Well looking at the low side pressue while operating, it shows to be between 50 and 70 PSI. Too high. Yes, you can add some more refrigerant at this point, thinking the charge is low, but this will only make it worse. Now you are overcharged, and the high side pressure is way too high. You must know where you are starting from to properly repair the AC system.

well, you wouldnt add with 50-70 LSP, but recovering or venting some refrigerant would cause a low charge. fact is, if theres an internal compressor failure, there isnt a charge level that will allow it to blow cold.

on the other hand, a restricted TXV would cause a low LSP, a starved evap, and hooking up a low side gauge will indicate to someone unexperienced that theres a low charge. adding refrigerant at this point will usually send the HSP high enough to cut out on the high side, putting you at square 1.

EDIT: on another note, ive seen WAYYY to many people unfamiliar with the characteristics of ac performance on a given car, and think theres something wrong with it. thats why i asked for the discharge temp readings, because hes comparing it to 'another car'

how much r134 should you use if the system has been completely evacuated? Is one of the bottle (14oz) enough usually?

a can is usually 12oz, IIRC.

itll take 1.10 lbs.

dont forget to add oil. :)