The PTC (Positive Temperature Coefficient) heater is installed at the exit or the backside of the heater core.
The PTC heater is an electric heater using a PTC element as an auxiliary heating device that supplements deficiency of interior heat source in highly effective diesel engine. The electric heater heats up the interior by directly heating the air that passes through the heater. The name itself implies that the element has a proportional resistance change sensitive to temperature.
ECM outputs a PTC ON signal and operates PTC relay 1. Then heater controller operates PTC relay 2 and PTC relay 3 with an interval of 15 seconds.
However, PTC relay 3 can be operated while battery voltage is above 12.4V.
PTC heater operates according to the following conditions :
Battery voltage : 12.4V or above
Engine : Running
Ambient temperature and coolant temperature
Ambient Temperature | Coolant Temperature | PTC Operation |
Below -20℃ (-4℉) | Below 75℃ (167℉) | ON |
10℃ (50℉) | Below 65℃ (149℉) | ON |
12℃ (53.6℉) or above | - | OFF |
- | 80℃ (176℉) or above | OFF |
