16019 - Customer Satisfaction Program. Some vehicles may have a condition in which a crack in the heating and cooling module temperature door control shaft may form and result in inconsistent air discharge temperature control. If the shaft cracks, the air discharge temperature may be up to 33 degrees Fahrenheit (20 degrees Celsius) cooler than the requested values, depending on the HVAC mode selected. Inspect the temperature valve control shaft for cracks. If the shaft is intact, install a reinforcing clamp around the temperature valve shaft to prevent the shaft from cracking. If more than one crack is present, replace the temperature control valve.