An improper gauge reading will relate to a specific problem. More than one problem may be
associated with particular gauge reading, however. A system operating normally will have a
low-side gauge pressure reading that corresponds with the temperature of the liquid
refrigerant as it becomes a vapor while removing heat from the air flowing over the
evaporator coil surface. The high-side gauge readings should correspond with the
temperature of the vapor as it becomes a liquid while giving up its heat to the ambient air
flowing through the condenser.
Any deviation from ambient dependant normal gauge readings, other than slight, indicates a
malfunction. This malfunction, if within the system, may be caused by a faulty control device,
a restriction, or defective component. It should be noted that improper mounting or location
of components in a newly installed system may affect system performance. The vehicle
engine may also affect system performance and will be note as abnormal gauge readings.