Did you evacuate the system before you charged it? Evacuating the system removes air and moisture. You do this with a vacuum pump. If you charged the system without evacuating it your system will not funtion properly. There should be a label somewhere under the hood stating how much freon the system operates on. When the system is running, the high side lines should be very warm if not hot. Only the low side line will be cold due to low pressure. The temperature of the refridgerant reacts with the pressure. If pressure is high so is the temperature. Low pressure - low temperature. With the system running at idle you should see low side pressure at 20-45 psi depending on the ambient temperature and high side at 150-300 psi depending on ambient temp and also system design. Some smaller systems run on a high side of 150-200 psi. But ambient temperature plays a part in the pressure readings of both high and low side. So it is hard to say what the exact reading should be.

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