PTC HEATER
Diesel engines make substantial power, but typically heat up rather slowly. Because the diesel engine heats slowly, the 2016 TITAN XD has added a Positive Temperature Coefficient (PTC) heater within the HVAC ducting to provide supplemental cabin heat. When current is applied, the PTC elements in the heating grid heat up. Then air from the blower motor passes through the PTC heating grid and is heated before exiting the HVAC vents.
PTC Heater
- The PTC heater is located on the side of the A/C assembly near the the LH center of the instrument panel.
- The PTC grid is made up of a ceramic material with barium titanate as the primary component.
- The PTC heater provides supplemental heat by warming the air as it flows through its electrically controlled heating grid.
- The PTC heater can be removed by disconnecting the electrical connector and removing two screws.
PTC Relays
- The PTC relays 1, 2, and 3 are located on the relay box in the engine compartment.
- The PTC relays are used by the A/C auto amp. to turn ON one, two, or three of the PTC heating elements.
- Each relay provides current to a specific section/element of the PTC heater.
- The A/C auto amp will turn ON one, two, or all three PTC relays depending on the heating requirements as determined by sensor inputs.
A/C Auto Amp.
- The A/C auto amp. uses signals from the in-vehicle sensor, ambient temperature sensor, intake sensor and sun load sensor.
- If engine coolant temperature is less than 158°F (70°C) and ambient temperature is less than 57°F (14°C), the A/C auto amp. will turn ON the PTC relays as needed.
- Once the engine coolant temperature exceeds 158°F (70°C), the A/C auto amp. will turn OFF all PTC relays, which will stop all current flow to the PTC heater elements.
Ambient Sensor
- The ambient sensor measures ambient air temperature. The sensor uses a thermistor that is sensitive to a change in temperature. The electrical resistance of the thermistor decreases as temperature increases.
NOTE:
To best evaluate PTC function, the ambient sensor can be unplugged, simulating a -22°F (-30°C) outside temperature. Engine coolant temperature must also be less than 158°F (70°C).
Wiring Diagram
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