Cool Down TEST - ATC AND MTC SYSTEMS

The Cool Down Test checks A/C system performance by measuring the system's ability to lower the evaporator temperature 11.11° C (20° F) as measured by the evaporator temperature sensor. The following are prerequisites of the Cool Down Test. Verify each of the following before running the Cool Down Test:

• For the ATC system, the Cool Down Test will NOT start if DTC B1031 or B1032 is active. If active, diagnose and repair either DTC before proceeding (Refer to HEATING & AIR CONDITIONING (ATC) - ELECTRICAL DIAGNOSTICS or HEATING & AIR CONDITIONING (MTC) - ELECTRICAL DIAGNOSTICS for a complete list of HVAC related symptoms).
• For the MTC system, the Cool Down Test will NOT start if DTC 31 or 32 is active. If active, diagnose and repair either DTC before proceeding (see HEATING & AIR CONDITIONING (ATC) - ELECTRICAL DIAGNOSTICS or HEATING & AIR CONDITIONING (MTC) - ELECTRICAL DIAGNOSTICS related symptoms).
• For both systems, verify that the refrigerant system has an adequate charge. Check and repair as necessary before proceeding. See Heating and Air Conditioning - Diagnosis and Testing .
• For both systems, verify that the blower motor operates correctly in all speeds. Diagnose and repair all blower motor related faults before proceeding.
• For both systems, verify that the ambient temperature of the work area is above 18.3° C (65° F) before proceeding. Move the vehicle to a warmer work area if necessary.
• For both systems, verify that the evaporator temperature is above 18.3° C (65° F) before proceeding.
• For both systems, verify that the A/C compressor is NOT running. If the A/C compressor is running, turn the A/C off and allow the A/C evaporator to warm up before proceeding.