Delphi Technologies, Inc.

Delco Electronics Corporation

R Thomas Fisher

J Roger Davis

Michael G McDermott

Ronald W Dale

Larry W Soutar

The present invention provides an HVAC fan control that includes a front fan switch, controller, rear fan switch, rear fan control circuit and a fan motor. The front fan switch and the rear fan switch electrically connect to the controller. Also, the fan motor is electrically connected to the rear fan control circuit and a front fan switch. Accordingly, the controller is responsive to inputs form the rear fan switch to operate the rear fan control circuit and select a desired fan motor speed when a logical ON condition is provided by the front fan switch.

Transient-resistant non-pulsed electronic automotive HVAC fan control

An improved current monitor for measuring current over a wide dynamic range. The current monitor includes a low current channel, a high current channel, and a switch for selecting the low current channel if the measured current is below a predetermined level and the high current channel if the current is above the predetermined level. The output of the high current channel is voltage encoded by adding a fixed offset. The current monitor determines that the measured current is from the low current channel if the reading is below the offset and from the high current channel if the reading is above the offset. A current level output device automatically outputs a decoded current reading based on this determination. The current monitor also incorporates a low current error compensation circuit to compensate for parasitic current when the current monitor is using the high current channel. The current monitor also incorporates a device for reducing the common mode error voltage to zero in the differential amplifiers used to convert current across shunt resistors in the low and high current channels to a voltage signal.

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Kokomo, IN, United States of America

R Thomas Fisher