Seat ALHAMBRA Owner's Manual page 173

The heater will switch just once each time. The timer will also have to be
switched back on every time it is required.
Note
Noise will be heard while the auxiliary heater is running.
When the air humidity is high and the outside temperature low, the
heating system may evaporate condensation from the auxiliary heater. In this
case, steam may be released from underneath the vehicle. This is completely
normal and there is no need to suspect a fault!
If the auxiliary heater runs several times over a prolonged period, the
vehicle's battery may run flat. To re-charge the battery, drive the vehicle for a
long distance. In general: drive for as much time as the auxiliary heating was
working.
Safety First Operating instructions
Heating, Ventilation and Air conditioning
Practical tips Technical Data
171