Nissan Repair: 95 Quest A/C, side ports, metal particles

Question
Hi Mr. Von Sudderth
I just replaced new FS-10 compressor with 8 oz of ester 100 uv dye oil, new accumulator, new orfice tubes (screen on the old orfice tubes is quite clean, except few metal particles), new o-rings on all joints,after vaccumed and hold for 3 hours as 28-29 Hg best I can tell by gauge, and recharge 52 oz of R134A . The front blows cool to about 70 deg. rear blows cool to about 65 deg. at 1000 r.p.m, manifold gauge show low side is 60 p.s.i, high side showed 270 p.s.i, the ambiant temp closer to condensor is 90 deg.
My question is:
-what is a spec. pressure on the low and high side ports?
-Any POSSIBLE things to make the a/c blowing colder?
Thank you for your time  

Answer
Tommy,

System pressures seem correct and the amount of R-134 and oil seems correct for your system.  I would check to see if the condenser is clean and free of debris.  The fans are both working?  There is no in cabin filter in the system.  I forget the year that they started that.  But, I have seen some that have never been changed out.  Have to remove the glovebox to get to it if you have one.  If the orfice tube has any metal in it it will screw up the cooling.  I am saying this due to your pressure reading on the low side when the RPMs are up.  I would change it out until you have no trash in the system.  So, if there is metal in it take it out and clean it and replace it and do another charge.  There are some booster products on the market that will get you a few degrees more cooling.  Simply remove the same amount from your system and replace it with what is in the can.  If the engine is running a little hot like needing a new thermostat and a radiator cap will also lead to the system not to get cool enough.  R-134 is 20 percent less efficient than R-12 so that has to be taken into account.  Any thermal addition to the equation will add heat and make the system less cool.