[richtazz]

You need an A/C guage set to compare high side and low side readings. Just reading the low side doesn't do much good, as the pressure will change with atmosperic changes (temp, humidity, etc...). You may have a partial blockage in the refrigerant lines, low refrigerant charge, or possibly even a slipping serpentine belt. At idle (or WOT), the PCM may disengage the A/C compressor clutch to keep the engine at proper idle RPM or to allow extra power if you're really in the gas, which in turn would cause the A/C to stop blowing cold.