Blower And Blower Speed Driver; Background; Power, Signal And Ground Circuit; Possible Failure Modes - New Holland T8010 Manual

BLOWER AND BLOWER SPEED DRIVER

NOTE: See Electrical Schematic sections 60 and 61.

Background

In automatic and defog/defrost modes, blower speed is selected by the controller based on the difference between
the desired setpoint and the actual cab temperature. Refer to ATC Operation in this section for further information
on how blower speed is selected, overridden and exceptions.
Various blower speeds are accomplished by modulating voltage to the blower motor with the blower speed driver.
There are no fault codes for the blower motor or blower driver, although code 120 indicates a fault in the blower
speed control circuit.

Power, Signal and Ground Circuit

12V is fed to the blower motor and blower driver on pin A from fuse 26 (30 amp) whenever accessory power is
present.
The voltage signal is fed from CJ8-5 to pin 3 on the blower speed driver.
The blower speed driver is grounded from SBC1-2 to chassis ground at ring terminal 173B. The blower motor is
grounded within the speed driver.
NOTE: Refer to Blower Speed, and Temperature Control Potentiometer in this Section for troubleshooting the
control potentiometer.

Possible Failure Modes

1. Blower motor failure.
2. Blower speed driver failure.
3. Open condition in power, signal or ground to blower motor or blower speed driver.
4. Blower motor or blower speed driver shorted to ground.
5. Controller failure.
Section 50 - Climate Control - Chapter 1
50-1-47