Audi 1999 TT Operating instructions

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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
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Repair Manual
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning
Engine ID CEP
B
CDM
A
CET
A
CCT
ABPY BUB CBR A
Edition 01.2011
Service
Service Department. Technical Information

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
List of Workshop Manual Repair GroupsList of Workshop Manual
Repair GroupsList of Workshop Manual Repair Groups
Repair Group
80 - Heating, Ventilation
87 - Air Conditioning
Technical information should always be available to the foremen and mechanics, because their
careful and constant adherence to the instructions is essential to ensure vehicle road-worthiness and
safety. In addition, the normal basic safety precautions for working on motor vehicles must, as a
matter of course, be observed.
Service
All rights reserved.
No reproduction without prior agreement from publisher.
Copyright © 2011 Audi AG, Ingolstadt D3E80068107

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Contents
80 - Heating, Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Servicing Heater System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Contact Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Performing Guided Fault Finding on Heating System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Heating System Electrical Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5 Heater Activation and Control Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Description and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Components Outside Passenger Compartment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 A/C Components Inside Passenger Compartment, Left Side . . . . . . . . . . . . . . . . . . . . . . 6
2.3 A/C Components Inside Passenger Compartment, Right Side . . . . . . . . . . . . . . . . . . . . . . 8
2.4 Heater Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Diagnosis and Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 Heat Output and Temperature Door Activation, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2 Temperature Door and Heater Output Activation, Checking . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3 Electrical Components Controlled by Heating System, Checking . . . . . . . . . . . . . . . . . . . . 16
4 Disassembly and Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 Heater Electrical Attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2 Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 Air Guide Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
87 - Air Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
1.1 A/C Compressor Belt Pulley, Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
1.2 A/C System Control and Regulation Components Outside Passenger Compartment . . . . 25
1.3 A/C System Control and Regulation Components Inside Passenger Compartment . . . . . . 27
1.4 A/C System, Operating After Filling Refrigerant Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.5 A/C and Refrigerant Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.6 A/C Air Distribution Housing Defroster Outlet Door . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.7 Adapter Cable for Activating Control Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.8 Checking Electrical Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.9 Climatronic Control Module J255 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.10 Contact Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.11 Dryer Cartridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.12 Dust and Pollen Filter with Activated Charcoal Insert . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.13 Evaporator, Cleaning with Ultrasound A/C Cleaner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
1.14 Fresh Air Blower Control Module J126 and Fresh Air Blower V2 . . . . . . . . . . . . . . . . . . . . 36
1.15 Painting Vehicles with A/C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.16 Performing Guided Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.17 Refrigerant Circuit, Draining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.18 Refrigerant Circuit, Repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
1.19 Refrigerant Circuit, Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.20 Refrigerant Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1.21 Refrigerant Circuit O-rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1.22 Refrigerant R134a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2 Description and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.1 Air Routing and Distribution in Passenger Compartment . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.2 A/C Unit Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.3 Refrigerant Circuit Components Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.4 Belt Pulley, Denso A/C Compressor, Version 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.5 Belt Pulley, Denso A/C Compressor, Version 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
2.6 Components Outside of Passenger Compartment, Group 1 . . . . . . . . . . . . . . . . . . . . . . . . 55
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
Contents i

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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
2.7 Components Outside of Passenger Compartment, Group 2 . . . . . . . . . . . . . . . . . . . . . . . . 57
2.8 A/C Components Inside Passenger Compartment, Left Side . . . . . . . . . . . . . . . . . . . . . . 59
2.9 A/C Components Inside Passenger Compartment, Right Side . . . . . . . . . . . . . . . . . . . . . . 61
2.10 Air Flow Door Motor V71 , Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
2.11 Refrigerant Circuit, Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
2.12 Air Intake and Outlet Openings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.13 Air Guide In Evaporator Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
2.14 Air Guide In Air Distribution Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
2.15 High Pressure Sensor G65 Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
3 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.1 Fastener Tightening Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4 Diagnosis and Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
4.1 A/C Compressor Regulator Valve N280 , Checking Switch-On Signal . . . . . . . . . . . . . . . . 76
4.2 A/C Unit, Checking Cooling Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
4.3 Causes of Odor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.4 Components Actuated by A/C System, Electrical Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
4.5 Condensation Water Drain Hose, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
4.6 Heating Performance Of A/C System, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4.7 Heated Seats, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
4.8 High Pressure Sensor G65 , Checking Pressure Signal . . . . . . . . . . . . . . . . . . . . . . . . . . 96
4.9 Passenger Compartment Forced Air Extraction, Checking . . . . . . . . . . . . . . . . . . . . . . . . 98
4.10 Plenum Chamber Water Drain, Checking and Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . 100
4.11 Rear Window Defogger, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
4.12 Wiring and Component Testing with Test Box VAG 1598A . . . . . . . . . . . . . . . . . . . . . . . . 101
5 Removal and Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
5.1 A/C Compressor, Removing From Bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
5.2 A/C Compressor, Removing From Bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.3 A/C Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
5.4 Air Intake Grille . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.5 Air Intake Housing with Recirculating and Air Flow/Fresh Air Door . . . . . . . . . . . . . . . . . . 115
5.6 Belt Pulleys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
5.7 Climatronic Control Module J255 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
5.8 Door Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
5.9 Dust and Pollen Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
5.10 Fresh Air Blower Control Module J126 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
5.11 Fresh Air Blower Control Module J126 and Fresh Air Blower V2 . . . . . . . . . . . . . . . . . . . . 141
5.12 Fresh Air Intake Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
5.13 Front Upper Body Outlet Temperature Sensors G385 / G386 . . . . . . . . . . . . . . . . . . . . . . 143
5.14 Heater Core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
5.15 High Pressure Sensor G65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
5.16 Instrument Panel Vents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
5.17 Interior Temperature Sensor Fan V42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
5.18 Refrigerant Circuit Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
5.19 Sunlight Photo Sensor G107 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
5.20 Temperature Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
6 Disassembly and Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
6.1 Electrical Components of A/C unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
6.2 A/C Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
6.3 Evaporator Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
7 Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
ii Contents

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
80 – Heating, Ventilation
1 General Information
⇒ “1.1 Servicing Heater System“, page 1
⇒ “1.2 Contact Corrosion“, page 1
⇒ “1.3 Performing Guided Fault Finding on Heating System“,
page 2
⇒ “1.4 Heating System Electrical Components“, page 2
⇒ “1.5 Heater Activation and Control Components“, page 3
1.1 Servicing Heater System
WARNING
Before working on electrical system (wiring), remove relevant
fuse(s).
Note
Disconnect battery before starting electric welding work on vehi‐
cle. Refer to ⇒ Electrical Equipment; Rep. Gr. 27 ; Removal and
Installation .
♦ Contact corrosion. Refer to
⇒ “1.2 Contact Corrosion“, page 1 .
♦ Notes for performing Guided Fault Finding on the heating, re‐
fer to
⇒ “1.3 Performing Guided Fault Finding on Heating System“,
page 2 .
♦ Checking the electrical components on the heating system,
refer to
⇒ “1.4 Heating System Electrical Components“, page 2 .
♦ Checking the electrical components actuated by the heating
system, refer to
⇒ “3.3 Electrical Components Controlled by Heating System,
Checking“, page 16 .
1.2 Contact Corrosion
Contact corrosion can occur if inappropriate fasteners (bolts,
nuts, washers, rivets, plugs, grommets, adhesives etc.) are used.
For this reason, the manufacturer only installs fasteners with a
special surface coating. Also, rubber and plastic parts and adhe‐
sive consist of materials that do not conduct electricity. These
parts, which have been tested and are aluminum compatible, are
also available as replacement parts. Refer to Electronic Parts
Catalog (ETKA).
Note
♦ Always install new parts if there is any doubt as to whether
parts can be reused.
♦ Original equipment replacement parts are recommended.
They have been tested and are compatible with aluminum.
Refer to Electronic Parts Catalog (ETKA).
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
1. General Information 1

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
♦ Audi accessories are recommended. Refer to Electronic Parts
Catalog (ETKA).
♦ Damage due to contact corrosion is not covered by warranty.
1.3 Performing Guided Fault Finding on
Heating System
♦ There are different versions of the Climatronic control module
-J255- heater control head. Pay attention to precise assign‐
ment on replacement. Refer to Electronic Parts Catalog (ET‐
KA).
♦ Heating system OBD is performed in the “Guided Fault Find‐
ing“ function with the Vehicle diagnosis, testing and informa‐
tion system -VAS5051B- in the "Guided Fault Finding"
function.
♦ The Climatronic control module -J255- , can currently be ex‐
changed as usual, component protection is not active at this
time. Check using Vehicle diagnosis, testing and information
system -VAS5051B- in the "Guided Fault Finding" function.
♦ If the Climatronic control module -J255- is supposed to be re‐
placed, check the coding and adaptation before removing it
using the “Replace Control Module“ function, starting with Ve‐
hicle diagnosis, testing and information system -VAS5051B-
in the "Guided Fault Finding" function.
1.4 Heating System Electrical Components
The electrical components for the heating system are identical to
the electrical components for the A/C system. The electrical test
for the various heater components is done in the same way as
the test for these components in the A/C system. Refer to
⇒ “1.8 Checking Electrical Components“, page 31 and Vehicle
diagnosis, testing and information system -VAS5051B- in the
"Guided Fault Finding" function.
On vehicles with no A/C, only a heater, various components that
are required for control on vehicles with A/C are not installed ( A/
C Compressor Regulator Valve -N280- , Right Temperature Door
Motor -V159- , Interior Temperature Sensor Fan -V42- etc.). Refer
to Vehicle diagnosis, testing and information system -VAS5051B-
in the "Guided Fault Finding" function and ⇒ Wiring diagrams,
Troubleshooting & Component locations.
Note
The function “electrical testing“ is not described in this Repair
Manual. Perform the electronic test with “Guided Fault Finding“.
This also contains information on the functions that should be
tested. Refer to Vehicle diagnosis, testing and information system
-VAS5051B- in the "Guided Fault Finding" function.
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
2 Rep. Gr.80 - Heating, Ventilation

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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
1.5 Heater Activation and Control Compo‐
nents
Note
♦ If there is a malfunction in the system, first check the Clima‐
tronic control module -J255- DTC memory. Refer to Vehicle
diagnosis, testing and information system -VAS5051B- in the
"Guided Fault Finding" function.
♦ If no fault is displayed, read the measured value block for the
Climatronic control module and activate the component with
the “output diagnosis test mode“ function on the Vehicle diag‐
nosis, testing and information system -VAS5051B- in the "Gui‐
ded Fault Finding" function.
♦ Electrical checking of the various control motors, potentiome‐
ters and senders is described in Guided Fault Finding. Refer
to Vehicle diagnosis, testing and information system -
VAS5051B- in the "Guided Fault Finding" function.
♦ Perform the following work after completion of repair opera‐
tions:
– Check Climatronic control module -J255- DTC memory and
erase any possible displayed malfunctions using Vehicle di‐
agnosis, testing and information system -VAS5051B- in the
"Guided Fault Finding" function.
– Check coding of Climatronic control module using Vehicle di‐
agnosis, testing and information system -VAS5051B- in the
"Guided Fault Finding" function.
– If necessary, check adaptation of the Climatronic control mod‐
ule using Vehicle diagnosis, testing and information system -
VAS5051B- in the "Guided Fault Finding" function.
– Perform heater basic setting, Climatronic control module using
Vehicle diagnosis, testing and information system -
VAS5051B- in the "Guided Fault Finding" function.
♦ Components outside passenger compartment, refer to
⇒ “2.1 Components Outside Passenger Compartment“,
page 4 .
♦ Components inside the passenger compartment, refer to
⇒ “2.2 A/C Components Inside Passenger Compartment, Left
Side“, page 6 and
⇒ “2.3 A/C Components Inside Passenger Compartment,
Right Side“, page 8 .
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
1. General Information 3

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
2 Description and Operation
⇒ “2.1 Components Outside Passenger Compartment“,
page 4
⇒ “2.2 A/C Components Inside Passenger Compartment, Left
Side“, page 6
⇒ “2.3 A/C Components Inside Passenger Compartment, Right
Side“, page 8
⇒ “2.4 Heater Components“, page 9
2.1 Components Outside Passenger Compartment
1 - Forced Air Extractor
❑ A forced air extraction
vent is installed at left
and right under rear
bumper.
❑ Sealing doors on air ex‐
traction vent must be
able to move freely and
close automatically.
❑ In order for the passen‐
ger compartment venti‐
lation to function proper‐
ly, the air ducts that run
through the luggage
compartment trim must
be unobstructed.
❑ Checking, refer to
⇒ “4.9 Passenger Com‐
partment Forced Air Ex‐
traction, Checking“,
page 98 .
2 - Intake Grille For Fresh Air
Intake
❑ Check for proper seat‐
ing, prevents foreign ob‐
jects (e.g. leaves) enter‐
ing intake housing of
heater unit.
❑ Check the bonded seal
for damage and proper
seating. This seal pre‐
vents water from flowing
through beneath the in‐
take grille into heater in‐
take housing.
❑ Removing and instal‐
ling, refer to
⇒ “5.12 Fresh Air Intake
Cover“, page 142 .
3 - Fresh Air Intake Cover
❑ Check the bonded seal for damage and proper seating. This seal prevents water between the windshield
lower frame and the cover from getting into the heater air intake shroud.
❑ Removing and installing, refer to ⇒ “5.12 Fresh Air Intake Cover“, page 142 and ⇒ Body Exterior; Rep.
Gr. 50 ; Removal and Installation .
4 - Coolant Fan -V7- and Coolant Fan 2 -V177-
❑ Different versions of the Coolant Fan and Coolant Fan 2 are installed depending on vehicle equipment.
Refer to Electronic Parts Catalog (ETKA).
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
4 Rep. Gr.80 - Heating, Ventilation

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
❑ In standard vehicle operation, the radiator fan is not activated by the Climatronic control module -J255- .
It will be displayed in the heater control head measured values block that the fan is not activated. Refer
to Vehicle diagnosis, testing and information system -VAS5051B- in the "Guided Fault Finding" function.
❑ The request to switch on the Coolant Fan -V7- is only transmitted by the Climatronic control module in
“Output Diagnostic Test Mode (DTM)“ via the databus system to the engine control module (ECM). Then,
with the engine running, the ECM activates the fan ( Coolant Fan -V7- and Coolant Fan 2 -V177- ) directly
or via the Coolant Fan Control Control Module -J293- . Check using Vehicle diagnosis, testing and in‐
formation system -VAS5051B- in the "Guided Fault Finding" function and ⇒ Engine Mechanical; Rep.
Gr. 19 ; Description .
❑ With engine running, the respective engine control modules switches, for example, the Coolant Fan and
Coolant Fan 2 (directly via the Coolant Fan Control Control Module) continuously to the desired output
(depending on engine type). Check using Vehicle diagnosis, testing and information system -VAS5051B-
in the "Guided Fault Finding" function and ⇒ Wiring diagrams, Troubleshooting & Component locations.
5 - Outside Air Temperature Sensor -G17-
❑ The measured value of the Outside Air Temperature Sensor is not used by the Climatronic control module
-J255- for controlling the heater. However, the measured value is used to calculate the permitted switch-
on time for the Heated Rear Window -Z1- .
❑ Measured value of Outside Air Temperature Sensor is evaluated by Instrument Cluster Control Module
-J285- and transmitted via Comfort CAN-Bus system to the Climatronic control module -J255- . Check
using Vehicle diagnosis, testing and information system -VAS5051B- in the "Guided Fault Finding" func‐
tion.
Removing and Installing
– Remove the bumper cover. Refer to ⇒ Body Exterior; Rep. Gr. 50 ; Removal and Installation .
– Disconnect connector on temperature sensor and unclip from mount in air duct
6 - Coolant Hose Connections To Heater Core
❑ Coolant hoses from connections to heater core, detaching and attaching, refer to
⇒ “5.14 Heater Core“, page 144 .
❑ Heat exchanger connection in engine coolant circuit, refer to⇒ Engine Mechanical; Rep. Gr. 19 ; Re‐
moval and Installation .
7 - Plenum Chamber Water Drains
❑ A water drain is installed at left and right in plenum chamber.
❑ Grommet, removing and installing, checking and cleaning, refer to
⇒ “4.10 Plenum Chamber Water Drain, Checking and Cleaning“, page 100 .
8 - Heated Rear Window -Z1-
❑ The command to heat the rear window is sent by the Climatronic control module -J255- via the Comfort
databus system. The vehicle electrical system control module -J519- controls the rear window defogger.
Refer to Vehicle diagnosis, testing and information system -VAS5051B- in the "Guided Fault Finding"
function and ⇒ Wiring diagrams, Troubleshooting & Component locations.
❑ Notes on function of heated rear window, refer to
⇒ “4.11 Rear Window Defogger, Checking “, page 101 .
❑ Rear window, removing and installing, refer to⇒ Body Exterior; Rep. Gr. 64 ; Removal and Installation
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
2. Description and Operation 5

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
2.2 A/C Components Inside Passenger Compartment, Left Side
1 - Left Front Seat Tempera‐
ture Sensor -G344- and Left
Front Heated Seat -Z45-
❑ Seat heater is not instal‐
led in all vehicles (op‐
tional equipment).
❑ When the seat heater is
activated, is displayed in
the Climatronic control
module -J255- meas‐
ured values block. Refer
to Vehicle diagnosis,
testing and information
system -VAS5051B- in
the "Guided Fault Find‐
ing" function.
❑ Seat heating, servicing,
refer to ⇒ Body Interior;
Rep. Gr. 74 ; Removal
and Installation .
2 - Diagnostic Connection
❑ Perform On Board Diag‐
nostic (OBD) on heating
system using Vehicle di‐
agnosis, testing and in‐
formation system -
VAS5051B- in the "Gui‐
ded Fault Finding" func‐
tion.
3 - Defroster Vent/Left Side
Window
❑ Removing and instal‐
ling, refer to⇒ Body In‐
terior; Rep. Gr. 70 ;
Removal and Installa‐
tion (Instrument Panel).
4 - Instrument Panel Vent, Left
❑ Removing and installing instrument panel vents, refer to ⇒ “5.16 Instrument Panel Vents“, page 152 and
⇒ Body Interior; Rep. Gr. 70 ; Removal and Installation (Instrument Panel).
5 - Instrument Cluster Control Module -J285-
❑ With the outside air temperature display -G106- .
❑ The Instrument Cluster Control Module -J285- evaluates the measured value of the Outside Air Tem‐
perature Sensor -G17- and then transmits it via the Comfort databus system to the Climatronic control
module -J255- . Check using Vehicle diagnosis, testing and information system -VAS5051B- in the "Gui‐
ded Fault Finding" function.
6 - Outside Air Temperature Display -G106-
❑ The Outside Air Temperature Display is a component of the Instrument Cluster Control Module -J285- .
❑ Measured value of Outside Air Temperature Sensor -G17- is evaluated by Instrument Cluster Control
Module -J285- and transmitted via Comfort CAN-Bus system to the Climatronic control module -J255- .
Check using Vehicle diagnosis, testing and information system -VAS5051B- in the "Guided Fault Finding"
function.
❑ If temperature display is incorrect, check temperature sensor measured value using Vehicle diagnosis,
testing and information system -VAS5051B- in the "Guided Fault Finding" function.
7 - Left Center Instrument Panel Vent
❑ Removing and installing instrument panel vents, refer to ⇒ “5.16 Instrument Panel Vents“, page 152 and
⇒ Body Interior; Rep. Gr. 70 ; Removal and Installation .
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
6 Rep. Gr.80 - Heating, Ventilation