Saab 900 II - Speed control for heating-system fan | HELLA
Saab
900 II
Year of manufacture: 1993 - 1998
Speed control for heating-system fan
In the above vehicles, a defective fan control unit can result in the passenger compartment fan operating only at the highest speed.
If the fan speed can no longer be controlled by the control unit or the fan operates only at the highest setting, the cause is probably a defect in the electronic fan control unit. In most cases, the transistor (MOSFET) on the circuit board has failed.
To access the fan control unit, the glove compartment must first be removed. If the left trim panel in the front passenger foot space is also removed, then there is free access to the control unit. Then the control unit can be replaced.
Somewhat skilled technicians could also repair the control unit by replacing the transistor.
For this procedure, the following accessories/replacement parts are needed:
- Transistor (Type IRFP064N), see drawing
- Soldering iron, ca. 30W
- Desoldering pump
- Solder
- Thermal grease
- Screwdriver, narrow
- Blade
- Harness tape, temperature-resistant
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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