It is possible that the air conditioning systems in the vehicles mentioned above may generate a humming noise during operation.
To fix this problem, check the part number on the air conditioning system's control device. If a 32-bit control device is installed, the vehicle manufacturer provides a modified software. If a 16-bit control device is installed, it must be replaced with a 32-bit control device and upgraded with a new software version.
Part numbers of the affected 32-bit control devices:
13 581 999 / 13 581 998 / 13 581 131 / 13 581 132 /
13 578 953 / 13 578 954
Part numbers of the affected 16-bit control devices:
13 578 112 / 13 578 113 / 13 344 280 / 13 344 281 /
13 577 783 / 13 577 784
Part numbers of the 32-bit replacement controllers:
13 581 998 (for vehicles with air conditioning systems with 2 zones)
13 581 999 (for vehicles with manual air conditioning systems)
Important safety note
Technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for use by suitably qualified personnel only.
Reprinting, distribution, reproduction, exploitation in any form or disclosure of the contents of this document, even in part, is prohibited without our express, written approval and indication of the source. The schematic illustrations, pictures and descriptions serve only for the purposes of explanation and representation of the instructions and cannot be used as a basis for installation or assembly work. All rights reserved.
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