₦airaland Forum

Hey car Gurus'
Someone pls clear me off doubt' My friend and I had an argument on fuel consumption while using Car AC. He said d amount of fuel consumed when AC is on low is same when high'. I disagreed with him, for me, the higher ur AC, the more consumption"
What's ur opinion guys?

ehm okay..
The belt that engages the compressor/ac is turned by the engine. So the higher the AC (fan), the more power supplied by the belt, the more fuel burned by the engine..simple

KingRex1:
ehm okay..
The belt that engages the compressor/ac is turned by the engine. So the higher the AC (fan), the more power supplied by the belt, the more fuel burned by the engine..simple

thanks bro

KingRex1:
ehm okay..
The belt that engages the compressor/ac is turned by the engine. So the higher the AC (fan), the more power supplied by the belt, the more fuel burned by the engine..simple

This is wrong. There's no connection between ur aC fan and compressor. All ur compressor does is compress it coolant into liquid, which on evaporating, causes cooling. D aC fan pushes d coolness into ur car.
The fan is powered by current from ur battery or alternator, that's why it blows even when ur engine is not turned on yet, but only produces cool air when ur engine starts turning d compressor.

To answer the question, higher fan speed "might" consume a "little" more fuel at higher speed bcoz d alternator will have to supply more current, which in turn means more work for d engine. If ur engine and alternator are in good shape, d engine will not notice anything and will run same, meaning no additional fuel consumption. So for a healthy car, d answer is NO, but for a weak engine, d answer might be yes.

Macmilla:
This is wrong. There's no connection between ur aC fan and compressor. All ur compressor does is compress it coolant into liquid, which on evaporating, causes cooling. D aC fan pushes d coolness into ur car.
The fan is powered by current from ur battery or alternator, that's why it blows even when ur engine is not turned on yet, but only produces cool air when ur engine starts turning d compressor.

To answer the question, higher fan speed "might" consume a "little" more fuel at higher speed bcoz d alternator will have to supply more current, which in turn means more work for d engine. If ur engine and alternator are in good shape, d engine will not notice anything and will run same, meaning no additional fuel consumption. So for a healthy car, d answer is NO, but for a weak engine, d answer might be yes.

How am i wrong wen we both sayin same thing, the engine turns the alternator, the engin turns the compressor, the engine turnns the fan.. A new car or not this requires more power frome the engine which increases fuel comsumption.
A car a/c comsumes 1 or 2 horsepower(nt so sure, browse that), where do you expect the engine to generate that from, since ac doesnt affects d car's torque nd speed? Its from gas my friend

[color=Blue]EVERY engine reacts to load placed upon it, regardless of it's mechanical state (new or old).

As long as the compressor is engaged, the engine will work harder. And will need to burn more fuel to produce more energy.

The alternator is free-rotating, as long as there are no heavy electrical consumers running. The more demands placed upon it in the form of electrical loads, the more energy the engine needs to produce to drive it. Again, more fuel needs to be burnt. Why do you think a worn belt gets really squeaky when you turn on your headlamps?

Just because you may not notice any change in gas mileage with more loads placed upon the engine, does NOT mean the said changes don't happen.

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KingRex1:
How am i wrong wen we both sayin same thing, the engine turns the alternator, the engin turns the compressor, the engine turnns the fan.. A new car or not this requires more power frome the engine which increases fuel comsumption.
A car a/c comsumes 1 or 2 horsepower(nt so sure, browse that), where do you expect the engine to generate that from, since ac doesnt affects d car's torque nd speed? Its from gas my friend

Are we talking of d whole AC system, or are we talking about d fan speed?
D whole AC unit definitely takes a toll on d engine and by extension, d fuel consumption. D question is whether the slight extra current needed to increase d fan speed actually increases ur fuel consumption.
Did u not understand his questions?

Siena:
[color=Blue]EVERY engine reacts to load placed upon it, regardless of it's mechanical state (new or old).

As long as the compressor is engaged, the engine will work harder. And will need to burn more fuel to produce more energy.

The alternator is free-rotating, as long as there are no heavy electrical consumers running. The more demands placed upon it in the form of electrical loads, the more energy the engine needs to produce to drive it. Again, more fuel needs to be burnt. Why do you think a worn belt gets really squeaky when you turn on your headlamps?

Just because you may not notice any change in gas mileage with more loads placed upon the engine, does NOT mean the said changes don't happen.

[/color]

Jeez!!! Did we pass comprehension in waec at all?
He said THE FAN SPEED, not d fan being on or off and not d whole AC unit. Jeez!

Macmilla:
Jeez!!! Did we pass comprehension in waec at all?
He said THE FAN SPEED, not d fan being on or off and not d whole AC unit. Jeez!

[color=Blue]Mr "I-Passed-WAEC", "Everyone-Else-Is-A-Dunce".

Please, quote where the thread starter mentioned Fan Speed.

The thread starter used the words "High" and "Low". High and low in automotive air conditioning systems can refer to fan speed, or temperature.

Compressors with positive displacement (magnetic clutch type) are either on or off. Selecting different temperature settings will NOT alter the load the compressor places upon the engine. Altering the fan blower motor speed WILL however modify the load the alternator sees, which will also be picked up by the engine which drives the alternator, and the injector's duty cycle will react accordingly, supplying more or less fuel as required.

Compressors with variable displacement (no clutch, but with a PWM-controlled swash plate) are ALWAYS on, unless OFF or ECON are selected. Selecting low temperature will produce a steeper swash plate angle, more gas is compressed. Selecting high temperature will produce the shallowest swash plate angle, less gas is compressed. So HIGH and LOW in terms of temperature settings here WILL impact on engine load primarily, and fuel consumption secondarily.

High and low in terms of fan speeds will modify the load the alternator sees, which in turn the engine has to drive.

When the thread starter made references to HIGH and LOW, he / she was NOT specific, so rather than make an assumption, I responded to what HIGH and LOW could refer to in modern automotive air conditioning, in BOTH respects - temperature and fan speed.

It's best to read, comprehend, and ask questions on any aspects you're not sure of, rather than insult other contributors, simply because you feel their powers of comprehension are inferior to yours. [/color]