Quote:
Originally Posted by redpoint5
Most vehicles have fairly high electrical draw just running the fans, perhaps around 200 W on high...
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I finally got around to measuring what my HVAC blower uses. All tests were done with the car off, so voltage was only around 12V:
Code:
Setting Current TotalPower MotorPower
Low 2.5A 30W 13W
Medium1 4.2A 50W 34W
Medium2 5.6A 68W 57W
High 9.5A 114W 114W
The difference between TotalPower and MotorPower is what is wasted in the speed control resistors. The power actually reaching the motor is approximately doubled with each increase in setting.
I was wrong about everything going through a 15A fuse. This is true for the low and medium settings, but when the blower is on high, a relay connects it almost directly to the battery through a 30A fuse.
EDIT: At 114W, running the fan adds about 0.06L/100km to my fuel consumption (based on 114W = 0.15hp = 0.04L/h = 0.06L/100km at 67km/h, which is my overall average speed). In US units, where the calculation is more complicated because we're working with reciprocals of fuel consumption, this costs me about 0.6mpg if I was averaging 47mpg.