From the owner's handbook for my RC ...
"Seat heater timer control
To enable seat heater timer control, press and hold the driver and front passenger seat
heater switches at the same time when the vehicle is stopped until a buzzer sounds once.
If a seat heater is turned on while seat heater timer control is enabled, the intensity of the
seat heater will automatically change from Hi→Mid→Lo.
The timing of the change in seat heater intensity differs depending on the temperature
inside the cabin, etc. when the seat heater is operating.
To disable seat heater timer control, press and hold the driver and front passenger seat
heater switches at the same time until a buzzer sounds twice."
I wonder if it's the same for your model? No mention regarding having to switch off before being able to use again though?