Ambient Temperature / Relative Humidity Reference Chart: Condition

WARNING: This page does not describe the selected car, but rather 41 other vehicles, including the 2003 BMW M5, 2003 BMW M3, 2003 BMW 540i, 2003 BMW 530i, and 2003 BMW 525i. However, it is still accessible from the selected car via links, so may be relevant.

The low-side gauge reading is low, or may go into a vacuum.
The high-side gauge reading increases as the system operates.
The discharge air from the evaporator is only slightly cool.
The expansion valve inlet may show heaving sweating or frost.
The high-pressure side is abnormally hot.

Fig 1: Expansion Valve Stuck Closed; Or Plugged By Moisture, Ice, Or Foreign Material
Courtesy of BMW OF NORTH AMERICA, INC.

The low-side gauge reading is too high.
The high-side gauge reading is too low.
The sight glass is free of bubbles; the system is fully charged. (If equipped)
The discharge air from the evaporator is not sufficiently cool.

Fig 1: Leak In Compressor, Or Drivebelt May Be Loose/Worn; Compressor Pistons, Rings, Valves, Or Cylinders May Be Excessively Worn Or Scored
Courtesy of BMW OF NORTH AMERICA, INC.

The low-side gauge reading is excessively high.
The high-side gauge reading is excessively high.
Bubble may appear occasionally in the sight glass. (if equipped) The liquid line is very hot.
The discharge air from the evaporator is warm

Fig 1: System Overcharged, Inoperative Condenser, Poor Airflow Through Condenser, Auxiliary Fan Inoperative
Courtesy of BMW OF NORTH AMERICA, INC.