Fig. 18.1. Location of the inspection window (1) for checking the refrigerant level
The sight glass is an indicator of the refrigerant level in the air conditioning system. To check the level, clean the glass and start the engine (Fig. 18.1). Press the air conditioner compressor on/off button, set the fan switch to the maximum speed position, and move the air temperature control knob to the maximum cooling position. After a few minutes of air conditioning operation in this mode, look at the sight glass.
If the sight glass is clean, the compressor electromagnetic clutch is engaged, the high pressure line (the compressor outlet hose) is cold, and the low pressure line (the compressor inlet hose) is warm, then the system is completely filled with refrigerant.
If the sight glass is clean, the electromagnetic clutch is engaged, but there is no significant temperature difference between the high and low pressure lines (i.e. the hose leaving the compressor and the hose inlet to the compressor), then some refrigerant has escaped from the system.
If foam or bubbles are visible in the sight glass, this may indicate that there is insufficient refrigerant. The system needs to be refilled with refrigerant.