A/C System, Troubleshooting

A/C System, Troubleshooting

Test requirements
Using V.A.G 1551 Scan Tool (ST), check DTC memory for any electrical, vacuum or air distribution malfunctions, correct/repair as necessary before proceeding.
- There are no shut off requirements for the compressor; read measuring value block, display group 001, display field 1
- Triggering and function of air flow flap and fresh air/recirculated air flap OK
- All air ducts, seals and covers are OK

If one of the following conditions exists, follow recommended service:

A/C does not cool (cooling has stopped completely)
- Check refrigerant system pressures.

Insufficient cooling during all driving or engine speed (RPM)
- Check refrigerant system pressures.
- Pressure switch -F129- shuts compressor off
- There is no outside air flow or air flow is severely restricted (evaporator iced up)

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"-refrigerant system overcharged:
- Discharge refrigerant system, evacuate & recharge.

With an otherwise properly operating A/C system, water sprays out of instrument panel vents:
- Check evaporator housing drain hose for proper routing (should not be kinked).
- Check evaporator housing drain valve.

NOTE:
- Check evaporator drain plugs for correct installation (should not be pinched or bent).
- Check drain valves. They must not be plugged with wax, dirt or undercoating (clean if necessary).
- Valve flaps must close properly.
- Check air plenum cover (must be properly installed and not damaged).