Symptom Troubleshooting Index

SYMPTOM TROUBLESHOOTING TABLE

Symptom	Diagnostic procedure	Also check for
Blower motor does not run at all	Probable cause: A problem in the blower motor power or ground circuit Do BLOWER MOTOR CIRCUIT TROUBLESHOOTING	Blown fuses No. 10 (7.5 A) or No. 57 (30 A) in the under-dash fuse/relay box Faulty blower motor relay Faulty heater fan switch Poor ground at G501 (see CONNECTOR TO FUSE/RELAY BOX INDEX ) Poor ground at G502: With navigation (see CONNECTOR TO FUSE/RELAY BOX INDEX ), Without navigation (see CONNECTOR TO FUSE/RELAY BOX INDEX ) Poor or loose connections at the terminals
The blower motor runs, but one or more speeds are inoperative	Probable cause: A problem in the circuits between the heater fan switch and the blower resistor Do BLOWER MOTOR CIRCUIT TROUBLESHOOTING	Faulty blower resistor Faulty blower fan switch Poor or loose connections at the terminals
The blower motor runs with the fan switch off	Probable cause: A short in the blower motor ground circuit Do BLOWER MOTOR CIRCUIT TROUBLESHOOTING	Faulty heater fan switch Poor or loose connections at the terminals
Driver's and passenger's side vent temperatures vary by more than 20°F (11°C)	Probable cause: The recirculation control door or the air mix door is malfunctioning Check the operation of the recirculation control cable and linkage (see RECIRCULATION CONTROL CABLE ADJUSTMENT ). Adjust or repair as needed Check the operation of the air mix door cable and linkage (see AIR MIX CONTROL CABLE REMOVAL/INSTALLATION ). Repair as needed	Faulty heater controls (see HEATER CONTROL PANEL DISASSEMBLY AND REASSEMBLY )
Insufficient heating	Check the coolant level (see COOLANT CHECK ) Check the radiator cap (see RADIATOR CAP TEST ) Check the coolant temperature during normal operation Check the heater core inlet hose temperature: If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, or a damaged or leaking water pump If it is HOT, check for restrictions in the heater core. Back flush or replace the heater core Check the operation of the air mix control cable and linkage (see AIR MIX CONTROL CABLE REMOVAL/INSTALLATION ) Check the blower motor unit for obstructions Check for air leaks around the ducts and vents	Damaged cylinder head gasket