87 Air conditioning does not cool
87 21 15 2063575/1 June 16, 2021.
Model(s)

Year

VIN Range

Vehicle-Specific Equipment

Q5, SQ5

2020

073111 - 999999

Not Applicable

Q5, SQ5

2021

All

Not Applicable

Condition
Customer states:
 The air conditioning does not blow cold enough, takes a long period of time to cool, or does not cool at all.

Technical Background
The refrigerant circuit head pressures are checked
and the diagnostic finding is determined that the
refrigerant volume in the circuit is very low or empty.
DTC B10AE21 (High-pressure sensor Lower limit not
reached) may be stored in the Heating/Air
Conditioning Electronics control module, E87
(address word 0008). Leak identification dye is added
to the refrigerant circuit along with a full charge of the
refrigerant and the vehicle is test driven. No obvious
leak can be seen under UV lighting. When using an
Figure 1. HVAC evaporator and housing.
electronic refrigerant leak detector at all of the
connections in the refrigerant circuit no leak can be
detected, however, when testing the central vents
and condensate drain it alerts that the evaporator
core may be the source of the leak. The evaporator
core is replaced and normal HVAC system operation
is restored.

Production Solution
Several improvements have been implemented in the evaporator core resulting in a more robust unit resistant to
leaking refrigerant.

Page 1 of 5
© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Service
All evaporator cores replaced in the Q5 models for which this TSB appears have been returned, laboratory
tested, and found to not have any leak whatsoever. This evidence confirms that while replacement of the
evaporator core solves the refrigerant leak, the root cause of the leak is not the evaporator core itself but likely a
compromised connection at the expansion valve either from the evaporator to the expansion valve, from either
of the refrigerant hose connections to the expansion valve or the expansion valve itself. This can conclude in a
false positive reading from the evaporator core and a positive refrigerant reading from a compromised
connection instead.
1. Should your diagnostic process conclude that any
and all possible refrigerant leaks have been
systematically excluded with the only confirmed
leak being detected at the evaporator core apply a
high level of scrutiny to the connection junction at
the evaporator core /expansion valve/refrigerant
lines for a possibly overlooked leak in these areas
(Figures 2 - 3).

Figure 2. Refrigerant connections in need of closer
observation.

Figure 3. Refrigerant connections to the expansion
valve.

Page 2 of 5
© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

2. If a refrigerant leak is detected from the
evaporator core/expansion valve/refrigerant line
junction, then replace the expansion valve and all
four O-rings without replacing the evaporator
(Figure 4). Re-test to ensure that the refrigerant
leak is solved without the replacement of the
evaporator core.

Figure 4. Leak at expansion valve connection evidenced
by residue from the contrast agent.
3. Should your diagnostic process conclude, however, that any and all leak possibilities from the evaporator
core/expansion valve/refrigerant line junction have been excluded but the electronic refrigerant leak detector
persists with detecting a refrigerant leak from the evaporator core. A replacement of the evaporator core is
the only logical course of action that remains then replace the evaporator along with all four original Oring seals and the expansion valve.
Do not only replace the evaporator core. Ensure that the evaporator, O-rings, and expansion valve are
carefully reassembled in their original state and positions, secured together and the entire assembly
packaged securely. This entire assembly will be requested for submission and laboratory analysis.
Note:
Evaporators replaced without the accompanying O-rings and expansion valve, received incomplete or
unassembled, or found to include components confirmed to not be the original components from the case
(verified through component serial numbers and production dates) as specified in this TSB will be debited.

Warranty
This TSB is informational only and not applicable to any Audi Warranty.

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© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Required Parts and Tools
Tool Number

Tool Description

Various

Electronic Refrigerant Leak Detector
NITROKITG

Automotive A/C Nitrogen Leak Test Kit
VAS 6160/VAS 6150

VAS tester with the current version of ODIS
(Windows 10)

Additional Information
All part and service references provided in this TSB (2063575) are subject to change and/or removal. Always
check with your Parts Department and/or ETKA for the latest information and parts bulletins. Please check the
Repair Manual for fasteners, bolts, nuts, and screws that require replacement during the repair.
©2021 Audi of America, Inc. All rights reserved. The information contained in this document is based on the
latest information available at the time of printing and is subject to the copyright and other intellectual property

Page 4 of 5
© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

rights of Audi of America, Inc., its affiliated companies, and its licensors. All rights are reserved to make changes
at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or
transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may
these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.

Page 5 of 5
© 2021 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of Audi of
America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the
publisher.