K Tahoe 4WD V8-5.7L VIN R (1996)
Radiator Cooling Fan Motor: Initial Inspection and Diagnostic Overview
1. CHECK condition of IGN E Fuse and AUX FAN Fuse. If either Fuse is open, then LOCATE and REPAIR source of overload. Replace Fuse(s).
2. CHECK that Grounds G105, G112, and G200 are clean and tight.
3. CHECK that the Auxiliary Cooling Fan Relay is securely mounted in its socket.
4. If the Recirculation Door Motor does not move to the Recirculation position when the Auxiliary Cooling Fan is operated by the Auxiliary Cooling
Fan A/C Pressure Switch, then Diode D101 may have opened.
5. If the Auxiliary Cooling Fan operates when the A/C controller places the Recirculation Door in the Recirculation position, then Diode D101 may
have shorted.
6. If the Recirculation Door moves to the Recirculation position in response to Auxiliary Cooling Fan operation by the Auxiliary Cooling Fan
Temperature Switch, then Diode D100 may have shorted.
7. If the Auxiliary Cooling Fan operates in response to the Auxiliary Cooling Fan Temperature Switch but not in response to the Auxiliary Cooling
Fan A/C Pressure Switch, then Diode D100 may have opened. CHECK for a broken (or partially broken) wire inside of the insulation which could
cause system malfunction but prove "GOOD" in a Continuity/Voltage check with a system disconnected. These Circuits may be intermittent or
resistive when loaded, and if possible, should be checked by monitoring for a Voltage drop with the system operational (under load).
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CHECK for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer "Troubleshooting
Procedures"). See: Diagrams/Diagnostic Aids
