Removal and Installation
Air Intake Unit
Special tools, testers and auxiliary items required
• Hose clamps up to dia. 25 mm (3094) or hose clamps up to dia. 40 mm (3093)
• Compressed air gun, commercially available
• Cooling system tester (V.A.G 1274) (and corresponding adapter)
Removing
- Switch off ignition.
- Release pressure in cooling circuit by opening cap on coolant expansion tank.
- Remove the plenum chamber cover.
CAUTION!
Even when the engine is cold, both pump/valve unit valves can be hot.
- Remove the windshield wiper arm and cowl panel trim
- Remove the windshield wipers and unclip the water channel from the air intake unit
- If necessary, remove the dome brace (not present in all vehicles).
- Remove the Alarm Horn (H12).
- If necessary, remove the Air Quality Sensor (G238) => [ Air Quality Sensor ] Service and Repair.
- Clamp off coolant hose - C - (from the engine to the Coolant Pump (V50)) e.g. using hose clamps up to 25 mm dia. (3094).
- Clamp off coolant hose - A - (return from the heat exchanger to the engine) e.g. using hose clamps up to 25 mm dia. (3094).
- Remove coolant hose - C - from its connection at the A/C system and secure it for later use.
- Disconnect electrical connector - C -.
- Remove bolt - B - (torque 7 Nm).
• To avoid having to remove the brake booster, from a 1/4 inch socket set use ratchet - A - with 2 long extensions - C -, the universal joint - D -, and a socket - E - to loosen and tighten the bolt - B -.
- Remove bolts - A - (tightening torque 7 Nm).
- Remove the water drain - D - from the opening in the plenum chamber or air intake unit.
- If necessary, remove the wiring harness, which is installed in the plenum chamber between the front wall and the air intake unit, from the various holders.
- Remove the air intake unit - E -.
Installing
Installation is carried out in the reverse order, when doing this note the following:
- Check the seal - A - in the air intake unit - B - for damage and to ensure it is installed correctly.
- Check both water drain grommets - G - for damage and deposits and clean if necessary.
- Check the grommets - F - for damage and to ensure they are installed correctly at the A/C unit and in the plenum chamber front wall.
- Clean the plenum chamber.
- Check the water drain - D - for damage and deposits and clean if necessary.
• The draining of water from plenum chamber may be impaired by deposits (leaves, diverse tree needles etc.) accumulating in plenum chamber water drains. In the car wash or during heavy precipitation, the water level in the plenum chamber rises, and water flows via the fresh air intake - A - into the air intake unit - B -.
• The water drain hose - C - should drain water that enters the air intake unit in small quantities during normal operation through the fresh air intake.
• The water drain hose - C - drains the water from the plenum chamber (via connector - E -) to the area behind the insulation mat in the center tunnel (there is a corresponding hole in the floor of the plenum chamber).
• A plastic piece - D - to reduce the diameter is insert in the water drain hose - C -. If the plastic piece - D - is not there, noise may result depending on the speed of the Fresh Air Blower (V2).
- Insert the screw - B - e.g. with a piece of "Butyl Cord" into the hole of the air distribution unit so that it does not fall out when the air intake unit is inserted.
• To avoid having to remove the brake booster, from a 1/4 inch socket set use ratchet - A - with 2 long extensions - C -, the universal joint - D -, and a socket - E - to loosen and tighten the bolt - B -.
- Install the air intake unit - E - and secure it with the screws - A - (tightening torque 7 Nm).
- Tighten screw - B - (tightening torque of 7 Nm).
- Install the removed components again in reverse order.
- After installation, check the grommet between engine compartment and plenum chamber at the coolant hose - C - for proper seating.
- Fill and bleed cooling circuit.
- After bleeding, check the cooling system to ensure it is sealed tight.
• When bleeding coolant circuit, take special care to ensure complete bleeding of heat exchangers. If air bubbles remain in heat exchangers, there may be complaints by customers about insufficient heating performance in winter, or different air temperature from vents at same setting in regulated mode.
- Check the DTC memory for the Climatronic Control Module (J255) A/C control head and erase any faults displayed if necessary => Vehicle Diagnosis, Testing and Information System VAS 5051.
- Perform a basic setting and output diagnostic test mode on the A/C system.