Heater Performance: Notes

See COOLING before performing the following tests. Check the engine coolant level and flow, engine coolant reserve/recovery system operation, accessory drive belt condition and tension, radiator air flow and the fan drive operation. Perform the A/C System Performance Test, which is found within the HVAC System Test. Refer to DTC-Based Diagnostics/HVAC - Standard Procedure . If any Diagnostic Trouble Codes (DTCs) are found in the CONTROL, A/C and Heater , repair as necessary.