A/C Charge Determination Test

The filter-drier is equipped with a sight glass that is used as a refrigerant level indicator only. This sight glass is not to be used for A/C performance testing. The filter/drier used in an R-134a system is not compatible with the filter/drier in an R-12 system.

To check the refrigerant level, clean the sight glass, start and run engine to operating temperature, then hold idle at 1100 RPM. Set air conditioning control on A/C, RECIRC and high blower. The work area temperature should be at least 70°F. If the compressor clutch does not engage, the refrigerant level is probably too low for the pressure cutoff switch to detect. Refer to "Leak Test" for testing procedures for the low pressure condition indicated. If no leak is found, evacuate and recharge the system as necessary. If compressor clutch engages, allow approximately one minute for refrigerant to stabilize, then view the refrigerant through the sight glass. The suction line should be cold to the touch and the sight glass should be clear. If foam or bubbles are visible in sight glass, the refrigerant level is probably low. Occasional bubbles are normal when the work area is above 110°F or below 70°F.

If suction line is cold and occasional bubbles are visible in the sight glass, block the condenser air flow to increase the compressor discharge pressure. Ensure engine does not overheat. Bubbles should disappear; if not, the refrigerant level is low.