A/C Condenser and Line Restrictions
A restriction in an 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, a temperature drop will be noticed as well. These performance robbing restrictions are far more common in 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 condenser. An automotive A/C condenser is located in front of the radiator and can be easily struck by road debris, resulting in kinks and possible leaks. A kink or restriction in the condenser results in a temperature difference at that point. The area just before the kink will be hotter (possibly real hot) than the point after the restriction. The line after the restriction will be 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.