| 1. | Operate the heater for one hour at maximum output in conditions of still air (wind speed ≤ 2 m/s), with all windows closed. If, however, having selected the maximum output the heater switches off automatically in less than an hour, the measurements may be made earlier. If the heated air is drawn from outside the vehicle the test shall be carried out at an ambient temperature of not less than 15°C. | a0c0 |