Refrigerant System Check

WARNING: This page is about a different car, the 1996 Buick Roadmaster. However, it is still accessible from the selected car via links, so may be relevant.

Ensure ambient temperature is at least 50°F (10°C). Check for restricted air flow at condenser and correct as necessary. Place auxiliary fan in front of radiator if vehicle is not equipped with engine driven fan. Start and run engine at 2000 RPM. Select AUTO mode and set temperature to 60°F (16°C). Enter diagnostics and select pointer number "-02". If EXT TEMP graphic is not displayed on A/C-heater control panel, go to next step. If EXT TEMP graphic is displayed on A/C-heater control panel, go to step 3).
If EXT TEMP graphic is not displayed, A/C-heater control panel is not requesting compressor operation. Select pointer number "-31" and display value. If value is 141 or less, replace A/C-heater control panel. If value is more than 141, go to INCORRECT OUTSIDE AIR TEMPERATURE DISPLAY.
Check that compressor clutch is engaged. If clutch is not engaged, go to A/C COMPRESSOR CLUTCH CONTROLS - ALL MODELS article. If clutch is engaged, check that primary electric cooling fan operates when compressor is engaged (if not equipped with engine driven cooling fan). If cooling fan does not operate, go to ELECTRIC COOLING FANS - ALL MODELS article.
Perform A/C SYSTEM PERFORMANCE test. If pressures are not within specification, check for moisture or restrictions in system. Check refrigeration system. If pressures are within specification, observe low side pressure as compressor cycles on and off. If compressor disengages at about 24 psi (1.7 kg/cm² ), and engages at about 45 psi (3.2 kg/cm² ), system is functioning properly and test is complete. If compressor does not engage or disengage at specified pressures, replace pressure cycling switch.