A/C Refrigerant System, Symptom Based Troubleshooting

A/C Refrigerant System, Symptom Based Troubleshooting

Test requirements
- Check DTC memory with VAG 1551 Scan Tool (ST) for any electrical, vacuum or air distribution malfunctions, correct/repair as necessary before proceeding. Check DTC Memory (Function 02)

- There are no shut off requirements for the compressor.

NOTE: If DTCs are present for either the A/C pressure switch -F129- or high pressure sensor -G65- and sufficient refrigerant is in the system, carry out electrical testing of these components.

- 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. A/C Refrigerant System Pressures, Checking

Insufficient cooling during all driving or engine speed (RPM)
- Check refrigerant system pressures A/C Refrigerant System Pressures, Checking
- Pressure switch -F129- disengages A/C clutch -N25-
- Coolant Fan Control (FC) Module -J293- disengages A/C clutch -N25- due to signal from high pressure sensor -G65-
- There is no outside air flow or air flow is severely restricted (evaporator iced up)

A/C compressor noisy
- Check for loose A/C compressor and compressor bracket mounting bolts. Tighten as necessary.
- 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 and recharge.

NOTE: Above condition may also be caused by excessive refrigerant (PAG) oil in system.

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).