Car heater

[frage]

Does a car use more fuel when the heater is on, or doesn't it make any difference?

[jake-the-peg]

Most car heaters work by diverting some of the coolant that was going to the radiator to a small radiator (called the heating matrix) which is in the path of one of the airflows into the cabin.

So there's no effect on the fuel economy.

Air conditioning however is run from a compressor off of the crankshaft's turning force so the engine has to do more work so fuel economy will be affected.

I guess it's cheaper to be hot than cool

[qapmoc]

The air-con affects not just the fuel consumption, my Toyota van only gets up long hills around here at slow speed anyway, if I put the air-con on when hill climbing I get overtaken by mopeds (normal ones not tuned up ones)

[frage]

Thanks jake-the-peg. That's much as I suspected. Great user name by the way!

[dilligaf]

As jake -the-peg said there will be no effect on the fuel economy when you turn your heater on untill you use the "blower" fan. That does make a difference although negligible.