A/C Condenser and Line Restrictions
A restricted A/C line or component results in a change or drop in pressure at that point. Because of the close relationship between pressure and temperature, the temperature drops as well. These performance-robbing restrictions are far more common on the high side of the system. This is because of the smaller diameter of the liquid lines.
Because of the sudden change in temperature, aiming an infrared thermometer at the suspected location is a great way to diagnose this condition.
Another common place for restrictions is the A/C condenser. An automotive condenser is located in front of the radiator. It can be struck by road debris, resulting in kinks and possible leaks. A kink or restriction in the condenser causes a temperature difference at that point. The area just before the kink is hotter (possibly real hot) than the point after the restriction. The line after the restriction is cooler and possibly frozen. Anytime a frozen point is found in a line or component, suspect a restriction. These restrictions can be caused by moisture, debris, or a kink in a line.