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-   -   Does heater consume engine power? (https://www.team-bhp.com/forum/technical-stuff/9556-does-heater-consume-engine-power.html)

We all know that A/C consumes engine power. What about heater. Whenever i turn on the heater, i feel that there is a minor drop in power. Dont know, it maybe psychological, but just to clarify.

I don't think so. Infact, you don't need the AC compressor to produce heat. My guess is that the heat produced by the engine is used to warm up the cabin.

I've seen race vids where drivers switch on the heater if they feel that the engine temp is risen beyond normal.

To confirm my theory, try switching on the heater when you start the car for the first time in the morn. You maynot get hot air instantly. The engine will have to warm up before this happens.

Shan2nu

the hot water / coolant is used to heat... warning dont run in heater mode with ac compressor ON..

doesn sap power, good once in a while to run in heater mode to kill the germs due to humidity inside the blower fan according to some :P

Yeah. The hot coolant that comes out of the radiator is circulated through a coil which gets heated up and hence makes the air hot. Till the engine gets warmed up, you won't get hot air since the coolant coming out of the radiator gets hot only as the engine becomes warm. No engine power is consumed.

Nope it's more like the reverse.

Heater cannot consume engine power. With the heater the heat dissipation of the engine becomes better and it improves efficiency. So theoretically the car should run better with the heater with better FE. Practically, however you won't see any difference. But there is certainly no loss of power.

I think I read in the maruti manuals... that one can use both ...... and alongside split the airflow... between floor (hot) and defroster (cold)....

though this doesn't work perfectly..... but it makes sense... as the heater normally takes... 10 times more effort to defrost the windscreen...... than the a/c.

Well if this is true, theres a slight possibility that the extra current drawn by the electric blower is causing this. (the same would happen if you turned the fan on in AC mode without the compressor on (ie AC switch off))

cya
R

There is absolutely no harm in using the heater when the AC is ON. In fact there is nothing like switching ON the heater except for switching on the fan and the adjusting the air control knob. You have two vents for the air flow into the cabin - one for the cool air and the other for the hot air. The air control knob controls the opening of these two vents and hence based on the position of the knob you get a mix of cold and hot air.

I agree completely with Shan2nu, the heater just pumps in heated air dissipated from the engine and has no effect in loss of power or fuel consumption. Albeit, it is good to use the heater in rains and cold weather to clear your front windsheild of mist. And yes it is good to bring down the engine heat ...

dear friends in most indian cars with manual aircon controls the ac just have to do double the job when the heater mode is switched on, and hence the statement..

if you get a chance to see the internals u will get it, even when you move the temp control from cold to hot the thermostat is not adjusted, rather the hot air component is increased, the thermostat is a fixed one which cuts of at only prescribed temp and make the compressor run continously.. again this is for manual control..

newer cars with automatic climate control have variable thermostats..

while on the topic, you can actually retro fit variable thermostat in cars which will actually help you cool better irrespective of fan speed as well as save gas, its kinda cheap gizmo which can be just plugged in and has a potentio meter kind of control

Jaggu is absolutely right. The coolant is circulated thru the coling coil. It is not the hot air or heat produced by the engine.

Nope, it doesn't consume engine power.... in my car, I tried turning ON the heat in the morning, hot air didn't come out instantly.... it took a while for the engine to warm up..... then it started blowing out hot air.

Putting the compressor on helps in preventing the windows from fogging up. Was a must in the east coast winters.

GTO

Is a must in delhi winters also. Since I do not have a heater in my DLS, I have to freeze myself to prevent the windows from fogging up :D.