18 seer AS charging problem,best way?

This is a brand new system I installed in my house. 18 SEER COMPRESSOR, AMERICAN STANDARD all equipment, varible speed fau, evap coil is rated for the system. I am a tech and have worked in this field for 10 years and have NEVER had a problem charging an r-22 set up. I think my problems are I am expecting to see a 18 degree temp differance even when the first stage ,small, compressor is running.

I have looked high and low for exact charging info, but would like someones input who might have knowlege of this type of system.

My problem, I only get a good cooling effect with the unit if it is what I consider to be over charged. At 90 degrees far outside, I am getting 76 suction pressure, 250 discharge pressure with an indoor temp of 70 degrees, supplied air temp is 55. That supplied air temp goes to 10 degrees splitonce the first stage compressor kicks on. <the smaller, longer running compressor.> I will be monitoring this thread to answer any questions someone willing to help might have.

I would like to know if this system is indeed over charged, by the way, it has never "sweated" on the suction line or made condensate...or if someone could point me to a thead that has exact charging dirrections I would appreciate it.

Hi nagzul,

What refrigerant is your system on?
Is it a split system (one indoor one outdoor unit as a matched set) or a condensing unit connected to a coil in a central air con system?
Has it got a fixed orifice/capiliary or an expansion valve?
Have you just replaced the outdoor unit?

Cheers Jon

sorry for the delay in posting, it is a r-22, txv. the whole system is brand new. 18 seer 3 ton condenser, 80k btu fau, and 3 ton high effenincy evap coil.

I just recovered all the r-22 and weighed in the 14 pounds that came from factory, plus .6 onces per line set above the 15 foot factory charge.<after vacuuming throughly ..again.>

I got a GREAT sweat at first. I was sooo happy, but than again it soon went back to a cold, but un sweating suction line.still no condensate. Any ideas? And THANKS fior the response.

Superheat.....subcooling......air flow in CFM? Size of system? Matching system? Wet bulb inside?