You cannot accurately charge a system with only a low-side gauge. I thought I made that clear. I cannot make ANY recommendation as to how much you need based solely on your single reading.
However, if you are reading the same value whether the A/C compressor is running or not and the reading is what you supplied, you are charged below the minimum required to even activate the compressor clutch.
If the compressor were cycling, you'd see the low side reading drop down to around 22-23 psi, the clutch would disengage, the low side pressure would rise back up to around 45 psi, and the cycle would repeat. The frequency of the cycle would be determined by several factors including the charge in the system, the ambient temperature, and the heat load being transferred. During more extreme conditions, it might never cycle (it would stay on constantly) and would still be normal.
Are you seeing any evidence that the compressor is engaging or not?
Last edited by projectSHO89; 06-20-2007 at 01:56 PM.