Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Heater And A/C Unit, Removing And Installing: Installing
Install In Reverse Order Of Removal.Note The Following:
Before installing, check all gaskets and grommets on the A/C unit for damage and replace if necessary.
-- Install the A/C unit -A- and the components also removed with the A/C unit (wiring harness "A/C unit", grommet on the evaporator refrigerant lines, etc.) in the vehicle
-- Coat the grommet -D- with grease and install it in the plenum chamber rear wall.
-- Install the support ring -E- in the grommet -D-.
-- Install the instrument panel cross member (central tube). Refer to INSTRUMENT PANEL CENTRAL TUBE, REMOVING AND INSTALLING .
-- Install the expansion valve mounting plate -A- to the refrigerant lines -B and C-.
-- Install the grommet -H- in the plenum chamber rear wall.
-- Check the position of the coolant and refrigerant line in both grommets, and if necessary, align the A/C unit so that the lines are not tensioned in the grommets.
-- Install the screws -A-.
-- Slide the strap -F- all the way to the bracket -H-, then turn it downward (when doing this, the bracket -G- locks the A/C unit to the strap)
-- Install the bolts -B-.
-- Connect both condensation water drain hoses to the A/C unit. Refer to CONDENSATION WATER DRAIN, REMOVING AND INSTALLING .
When installing the intermediate piece, -D-, the air guides to the rear footwells -A and B- and the air guide to the vent in the rear center console -C- make sure that they fit correctly and are securely connected. If the connection points are not connected tightly, warm or cool air could leak out and influence how the A/C system works (this air will be drawn in by the Interior Temperature Sensor Fan -V42- and the measured value for the Instrument Panel Temperature Sensor -G56- will deviate from the actual temperature in the passenger compartment).
The intermediate piece -D- latches on the air outlet openings on the air conditioner. There are slits inside the intermediate piece -D-. If the door position is incorrect, especially on vehicles with the "Convenience" A/C system, whistling noise can come from these slits. The upper slits are covered with tape during production (adhesive strips from 02/2009 as a running change). Refer to REAR VENT AIR GUIDE SLOTS, SEALING .
-- Install the air intake housing. Refer to HEATER AND A/C UNIT AIR INTAKE HOUSING, REMOVING AND INSTALLING .
-- Install the expansion valve. Refer to EXPANSION VALVE, REMOVING AND INSTALLING .
-- Install the refrigerant line with inner heat exchanger. Refer to REFRIGERANT LINES WITH INNER HEAT EXCHANGER, REMOVING AND INSTALLING
-- Make sure the grommet -H- fits correctly in the back of the plenum chamber.
-- Pay attention to the marking and properly connect the coolant hoses to the heater core.
A - Supply hose from cylinder head
B - Return to the coolant pump
-- Connect the coolant hose -A- to the heater core coolant pipe (pay attention to the marking) and secure it with the clamp -D-.
-- Attach the coolant hose to the heater core -B- onto the coolant pipe -F- just far enough as to not cover the bleed hole -G-.
-- Remove the hose clamp from the coolant hose -A-.
-- Fill The Coolant Expansion Tank With Coolant. Refer to COOLANT, DRAINING AND FILLING [CAED, CAEB, CPMB, CPMA] / COOLANT, DRAINING AND FILLING [CCBA, CGXC] .
-- Carefully force the coolant out of the coolant overflow reservoir into the heater core using, for example, the hand pump from the Cooling System Tester:VAG1274B .
-- As soon as the coolant comes out the ventilation hole -G-, install the coolant hose -B- on to the coolant pipe -F- at the marking.
-- Secure the coolant hose -B- with the clamp -E- on the marked location.
-- Remove the hose clamp from the coolant hose -B-.
-- Add More Coolant To The Coolant Expansion Tank, if necessary. Refer to COOLANT, DRAINING AND FILLING [CAED, CAEB, CPMB, CPMA] / COOLANT, DRAINING AND FILLING [CCBA, CGXC] .
This procedure completely bleeds the cooling system. If, for some other reason, there is still some air in the cooling system, bleed the coolant system after installing all of the removed components, if necessary. Refer to COOLANT, DRAINING AND FILLING [CAED, CAEB, CPMB, CPMA] / COOLANT, DRAINING AND FILLING [CCBA, CGXC] .
Check the Connections at the Heater Core for Leaks as Follows:
-- Carefully increase the pressure in the coolant circuit by using, for example, the hand pump of the Cooling System Tester:VAG1274B .
-- Check coolant circuit for leaks, pay particular attention to the connection between coolant hoses and heater core Engine Mechanical.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.