On the above mentioned vehicles a blocked condensed water drain hose can cause a short circuit in the electrical booster heater.
The function of the electrical (PTC) booster heater in the heater unit can be significantly degraded by a blocked condensed water drain.
Due to the fact that the condensed water is not drained to the exterior, there is a risk of an electrical short circuit. In an extreme case there is a risk of a cable fire.
The problem has already been addressed by the vehicle manufacturer, the vehicles checked during a recall campaign and the drain hose/drain valve renewed.
It must be assumed, that for a variety of reasons not all vehicles have been checked and/or repaired.
Please take this information into account, particularly in relation to complaints about poor heating performance.
Important safety notice
The following technical information and tips for practical use have been set up by HELLA in order to offer professional support to automotive workshops in their daily work. The information available here on this website is only to be used by appropriately trained specialist staff.
The reprinting, distribution, reproduction, exploitation in any form and 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, figures and descriptions are for explanation and presentation of the document text and cannot be used as a basis for installation or design. All rights reserved.
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