A/C System Performance
WARNING: This page is about a different car, the 1999 Pontiac Firebird and 1999 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
- Rotate temperature control knob from full cold to full hot and back to full cold. Listen for temperature valve to seat in both full hot and full cold position. If temperature valve seats in both positions, go to next step. If temperature valve does not seat in both positions, go to step 4
.
- Park vehicle out of direct sunlight. Close all doors and windows. Open engine hood. Place vehicle in Park (A/T) or Neutral (M/T), and set parking brake. Set temperature control to maximum cold, maximum A/C, and blower to high speed. Start engine and go to next step.
- Observe A/C compressor. If compressor engages, go to next step. If compressor dose not engage, see A/C COMPRESSOR CLUTCH CONTROLS - ALL MODELS article.
- Connect Tech 1 scan tool with powertrain cartridge to Data Link Connector (DLC). Select FIELD SERVICE mode. Using Tech 1 scan tool, turn on cooling fans. Check cooling fan operation. If both cooling fans are operating, go to next step. If both cooling fans are not operating, see ELECTRIC COOLING FANS - ALL MODELS article.
- Connect A/C manifold gauge set. Place thermometer at instrument panel center vent. Set temperature control to maximum cold, maximum A/C, and blower to high speed. Run engine at idle for 2 minutes. Note high-side and low-side pressures on A/C manifold gauge set. Determine relative humidity and ambient air temperature. Ensure system is operating within specified range. See A/C SYSTEM PERFORMANCE PRESSURE SPECIFICATIONS
and A/C SYSTEM PERFORMANCE TEMPERATURE SPECIFICATIONS
tables.
- If system is operating within specified range, system is okay. If system is not operating within specified range, check Variable Displacement Orifice Tube (VDOT) system. See MANUAL A/C-HEATER SYSTEMS - TROUBLE SHOOTING article.
A/C SYSTEM PERFORMANCE PRESSURE SPECIFICATIONS
| Ambient Temp. °F (°C) |
High Pressure psi (kg/cm
) |
Low Pressure psi (kg/cm
) |
| 70-80 (21-29) |
115-190 (8.1-13.4) |
24-34 (1.7-2.4) |
| 70-80 (21-29) |
115-200 (8.1-14.1) |
25-37 (1.8-2.6) |
| 80-90 (27-33) |
140-215 (9.8-15.1) |
28-38 (2.0-2.7) |
| 80-90 (27-33) |
150-235 (10.5-16.5) |
30-40 (2.1-2.8) |
| 90-100 (33-38) |
165-260 (11.6-18.2) |
34-43 (2.4-3.0) |
| 90-100 (33-38) |
185-270 (13.0-19.0) |
36-48 (2.5-3.4) |
| 100-110 (38-44) |
210-290 (14.8-20.4) |
40-49 (2.8-3.4) |
| 100-110 (38-44) |
220-310 (15.5-21.8) |
43-52 (3.0-3.7) |
A/C SYSTEM PERFORMANCE TEMPERATURE SPECIFICATIONS
| Ambient Temp. °F (°C) |
Center Vent Temp. °F (°C) |
| 70-80 (21-27) |
38-48 (3-9) |
| 70-80 (21-27) |
40-55 (4-13) |
| 80-90 (27-33) |
38-55 (3-13) |
| 80-90 (27-33) |
45-65 (7-18) |
| 90-100 (33-38) |
45-63 (7-17) |
| 90-100 (33-38) |
55-68 (13-20) |
| 100-110 (38-44) |
53-64 (12-18) |
| 100-110 (38-44) |
58-70 (14-21) |