Thanks for futher instructions. Took a glance at the car now. On idling the upper hose got a bit warm after 3-4 minutes, not hot. Was about as warm after the motor has been running about 10 minutes. Then also the downer was warm. The heater blows strongly at every speed but the air coming in the cabin is not hot, only warm. I think it is a bit warm also at the highest speed but feels colder as the blow is stronger. Perhaps it would be easiest to change the thermostat at first. Is there anything in these symptons referring to that the cell might be blocked?