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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 13 (HVAC System - Automatic) >> Diagnostic Information and Procedures >> Blower Motor Malfunction >> Circuit/System Description

Circuit/System Description

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

Blower Motor Control Module 

The blower motor control module is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive and ground circuits enable the control module to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the blower motor control module in order to command the blower motor speed. The control processor uses the blower motor ground or low reference as a low side control to adjust the blower motor speed.

Air Speed 

The blower motor forces air to circulate within the vehicles interior. The vehicle operator determines the blower motors speed by placing the blower knob dial in a desired speed position or by selecting automatic operation. In manual operation, the blower has six speed selections. The HVAC control module may alter the blower motor speed due to compensating factors. In automatic operation, the HVAC control module will determine what blower speed is necessary in order to achieve or maintain a desired temperature. In manual and automatic operation, the blower speed temporarily reduces speed during transition between outlet modes.

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