HVAC_MAX_DEFROST_ON
What it is
On/off max defrost
When MAX DEFROST is on, the ECU may adjust the vent position, fan speed, temperature, etc as necessary to defrost the windows as quickly as possible. Any parameters modified as a side effect of turning on/off the MAX DEFROST parameter shall generate onPropertyEvent() callbacks to the VHAL. The AreaIDs for HVAC_MAX_DEFROST_ON indicate MAX DEFROST can be controlled in the area. For example: areaConfig.areaId = {ROW_1_LEFT | ROW_1_RIGHT} indicates HVAC_MAX_DEFROST_ON only can be controlled for the front rows.
This property is defined as VehiclePropertyAccess.READ_WRITE, but OEMs have the option to implement it as VehiclePropertyAccess.READ only.
How the ID is built
A property ID is a 32-bit value packing four fields. Reading 0x15200507 apart:
| Field | Mask | Value | Means |
|---|---|---|---|
| Group | 0xf0000000 | 0x10000000 | SYSTEM |
| Area | 0x0f000000 | 0x05000000 | SEAT |
| Type | 0x00ff0000 | 0x00200000 | BOOLEAN |
| Ordinal | 0x0000ffff | 0x00000507 | 0x507 |
Reading it from an app
CarPropertyManager mgr = (CarPropertyManager)
car.getCarManager(Car.PROPERTY_SERVICE);
boolean value =
mgr.getBooleanProperty(VehiclePropertyIds.HVAC_MAX_DEFROST_ON, areaId);This property can be read and written, though an OEM may implement it as read-only. It fires a callback whenever the value changes.