Sight Glass Refrigerant Level Test

SIGHT GLASS REFRIGERANT LEVEL TEST




The sight glass is a refrigerant level indicator. To check the refrigerant level, clean the sight glass and start the vehicle engine and hold engine speed at 1500 rpm. Push the A/C button to operate the compressor, place the blower switch to high and move the temperature control lever to max cool. After operating for a few minutes in this manner, check the sight glass.
1. If bubbles are visible occasionally in the sight glass and disappear when engine speed is raised, the magnetic clutch is engaged, the compressor discharge line is warm and the compressor inlet line is cool; the system may be overcharged.
2. If the sight glass is clear, the magnetic clutch is engaged and there is no significant temperature difference between compressor inlet and discharge lines; the system has most of its refrigerant charge.
3. If the sight glass shows foam or bubbles, the system could be low on refrigerant or the receiver drier is restricted. The system has to be tested, leak checked then recharged with refrigerant.