Insufficient heating
Diagnostic Procedure
1.
Check the coolant level
2.
Check the radiator cap
3.
Check the engine coolant temperature (ECT) during normal operation with the HDS
4.
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
5.
Do the blower request circuit troubleshooting
6.
Do the air mix control motor test
7.
Check the blower motor unit for obstructions
8.
Check for air leaks around the ducts and vents
Also Check for
HVAC DTCs
Damaged cylinder head gasket
