Insufficient Heating

Insufficient heating

Check the coolant level Testing and Inspection

Check the radiator cap Testing and Inspection

Check the coolant temperature during normal operation

Check the heater core inlet hose temperature:

If it is COLD, check the heater valve and the cable for proper operation Adjustments restrictions in the hose, a damaged or leaking thermostat, or a damaged or leaking water pump an operation of the heater valve

If it is HOT, check the heater valve and the cable for proper operation Adjustments. Back flush or replace the heater core

Check the operation of the air mix doors:

Driver's Driver's Air Mix Control Motor Test

Passenger's Passenger's Air Mix Control Motor Test

Also check for

Climate control DTCs Initial Inspection and Diagnostic Overview

Also check for

Damaged cylinder head gasket