Insufficient Heating (With A/C)

Insufficient heating

Diagnostic Procedure:

1. Check the coolant level; R18A1 engine, Testing and Inspection K20Z3 engine Testing and Inspection

2. Check the radiator cap; R18A1 engine, Testing and Inspection K20Z3 engine Testing and Inspection

3. Check the coolant temperature during normal operation

4. Check the heater core inlet hose temperature:

5. If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, or a damaged or leaking water pump

6. If it is HOT, check for restrictions in the heater core. Back flush or replace the heater core

7. Do the air mix control motor test Air Mix Control Motor Test

8. Check the blower motor unit for obstructions

9. Check for air leaks around the ducts and vents

Also check for:

- HVAC DTCs How To Troubleshoot The Heating and A/C Systems (With A/C)
- Damaged cylinder head gasket