S10/T10 Blazer 4WD V6-262 4.3L VIN Z (1994)
Blower Motor: Initial Inspection and Diagnostic Overview
Circuit Operation
BLOWER CONTROLS
In all blower speeds except HI, the HTR A/C Fuse supplies current to the Blower Motor. In high speed operation, current from the Blower Switch
energizes the High Blower Relay, permitting current to flow from the Battery Junction Block to the Blower Motor.
Blower Low Speed Operation
The Blower Motor operates only in Low Speed through the A/C-Heater Selector Switch. With the A/C-Heater Selector Switch in MAX A/C,
NORM A/C, BI-LEVEL, VENT, HEAT or DEFROST, voltage through the A/C-Heater Selector Switch is available to the Blower Resistors
through the BRN/WHT (64) wire. The current then flows through all three resistors and the normally closed contacts of the High Blower Relay to
the Blower Motor and the Blower Motor runs at Low speed.
Blower Medium Low Speed Operation
With the Blower Switch in M1, current flows from the HTR A/C Fuse, through the A/C-Heater Selector Switch, the BRN/WHT (64) wire and the
Blower Switch to the TAN(63) wire at the Blower Resistors. Current then flows through two of the resistors and the normally closed contacts of
the High Blower Relay to the Blower Motor. The Blower Motor then runs at Medium Low speed.
Blower Medium High Speed Operation
With the Blower Switch in M2, the blower operates the same as in the Medium Low speed, except that the current is directed to the Blower
Resistors through the LT BLU (72) wire. Current passes through only one resistor. The Blower Motor then runs at Medium High speed.
Blower High Speed Operation
With the Blower Switch in HI, current bypasses the Blower Resistors and flows to the High Blower Relay through the ORN (52) wire. This current
energizes the relay and closes the normally open contacts of the relay. Current then flows from the Battery Junction Block through the relay to the
Blower Motor, and the Blower Motor runs at High speed.
Preliminary Checks
1. Check condition of HTR AC Fuse.
2. If fuse is blown, locate and repair source of overload. Replace fuse.
3. If fuse is not blown proceed with diagnostics. See:
Circuit Operation
The Blower Motor Fan delivers air to the interior of the vehicle. Its speed is controlled by the Blower Switch and the Blower Resistors. When the
Ignition Switch is in RUN, battery voltage is supplied to the Blower Switch through the HTR A/C Fuse. With the Blower Switch in LO, voltage is
supplied across both Blower Resistors and the Blower Motor. The Blower Motor runs at its slowest speed. With the Blower Switch in MED, one of the
Blower Resistors is bypassed and the Blower Motor runs faster. When the Blower Switch is set to HI, battery voltage is supplied directly to the Blower
Motor and the Blower Motor runs at its fastest speed.
Preliminary Checks
1. Check condition of HTR A/C Fuse. If fuse is blown, locate and repair source of overload and replace fuse.
2
If fuse is not blown, proceed with Diagnostic Procedures. See:
