( TL19E00G24100000000HBAT00 )

Heating Symptom Troubleshooting Index

Symptom | Diagnostic procedure | Also check for
--- | --- | ---

Blower and heater controls do not work

Heater control power and ground circuit troubleshooting

- HVAC DTCs
- Blown fuse No. 16 (7.5 A) in the driver's under-dash fuse/relay box
- Poor ground at G401
- Cleanliness and tightness of all terminals

Center display is not indicated

Audio communication line circuit troubleshooting

- HVAC DTCs
- Cleanliness and tightness of all terminals

Blower fan runs slower than expected in cold weather

ECT troubleshooting: ECT sensor 2 circuit low voltage, R20A3 engine model, K24Z3 engine model: ECT sensor 2 circuit high voltage, R20A3 engine model, K24Z3 engine model
NOTE: It is normal for the blower to run slowly until the engine coolant temperature begins to rise. If the blower continues to run slowly for an abnormal length of time, continue to troubleshoot the problem.

- Powertrain DTCs, R20A3 engine model, K24Z3 engine model
- Blower motor operation

HDS does not communicate with the heater control unit or the vehicle | Troubleshoot the DLC circuit, R20A3 engine model, K24Z3 engine model |

Insufficient heating

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Check the coolant level, R20A3 engine model, K24Z3 engine model
Check the radiator cap; R20A3 engine model, K24Z3 engine model
Check the operation of the air mix control motor and door
Check the coolant temperature
Check the blower motor unit for obstructions
Check for air leaks around the ducts and vents
Check the inlet hose temperature

- If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, and a damaged or leaking water pump.
- If it is HOT, check for restrictions in the heater core. Back flush the heater core using standard commercially available equipment, or replace the heater core.

Damaged cylinder head gasket