A/C System Troubleshooting

A/C Refrigerant System (R-134A), Troubleshooting


NOTE: The following information applies if and when low pressure can be checked or tested (either with an adaptor or by AG changing service valves).


Test requirements
Using VAG1551 Scan Tool (ST), check Diagnostic Trouble Code (DTC) memory for any electrical, vacuum or air distribution malfunctions.
- If one of the following conditions exists, follow recommended service:

A/C does not cool (cooling has stopped completely)
- Check A/C system pressures. A/C System Pressures, Checking

Insufficient cooling during all driving speeds or Engine Speeds (RPM)
- Check A/C system pressures. A/C System Pressures, Checking

No cooling or insufficient cooling after driving several miles
- Check A/C system pressures. A/C System Pressures, Checking

A/C compressor switches OFF via low pressure switch -F73-
- Check A/C system pressures. A/C System Pressures, Checking

No air flow from vents or air flow is severely reduced after driving several miles (evaporator iced up)
- Check A/C system pressures. A/C System Pressures, Checking

A/C compressor noisy
- Tighten A/C compressor and compressor bracket mounting bolts using torque wrench.
- Check routing of A/C refrigerant hoses and lines; hoses and lines must not contact other components and must be installed without binding, reposition or realign as necessary.

A/C compressor noisy immediately after switching A/C ON and/or when driving around corners or braking (refrigerant shock) system is overcharged
- Discharge A/C refrigerant system, evacuate and recharge

With an otherwise properly operating A/C system, water sprays out of instrument panel vents
- Check evaporator water drain hose for proper routing (should not be kinked).
- Check evaporator water drain valve.
- Must not be plugged with wax, dirt or undercoating (clean if necessary)
- Valve flap must close properly
- Check plenum tray.
- Must be properly installed and not damaged