How Much Power Does the AC Draw From the Engine?

Most cars these days come with air conditioning as a standard feature – gone are the days when it was an expensive extra (for most of us, anyway). The HVAC system is an important accessory, and helps you stay cool in the car when it gets hot outside. However, the AC is powered by your engine – the serpentine belt that runs your alternator, water pump, power steering pump and other accessories also turns the pulley for the AC compressor/clutch.

How the air conditioning system affects the engine

Because the system is powered by your engine, it pulls energy from it during operation, which can have an effect on engine performance. You’ve likely noticed your car’s engine RPMs increasing at idle when the compressor kicks on. It does this to offset the power drawn by the air conditioning system.

As to the question of how much power it draws, there’s no one answer, as it depends on the make and model, the engine, the condition of the engine and the air conditioning system and much more. It also depends on your acceleration and the year (most cars manufactured after 2000 have a relay that shuts off air conditioning at WOT (wide open throttle)) to ensure ample power for the engine under hard acceleration.

You’ll also find that the power drawn from the engine has a more noticeable impact with smaller engines. If you drive a subcompact with a small four-cylinder engine, your engine will be much more affected during AC operation than a big block V8 engine, even if the amount of power drawn by the air conditioner is identical between the two cars.


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Diego

21 years of experience
564 reviews
Diego
21 years of experience
Chevrolet Cruze - Car surges when air conditioning is on Inspection - Phoenix, Arizona
Came on time found out exactly what the problem was and didn't even take him an hour but then again I don't know if he checked everything I had read he was gonna check. Just happy I can get it fixed now
Dodge Caravan - Air Filter - Buckeye, Arizona
second time, also good service!

Emmette

36 years of experience
282 reviews
Emmette
36 years of experience
Honda Accord - Car surges when air conditioning is on - Woodbridge, Virginia
Emmette came out and did an inspection on my car. (The only reason I am not giving five stars is due to the fact that no actual repairs were made on my vehicle) He seemed very personable and professional. We actually talked about different things, and he seemed responsive to my questions. Additionally, he made a recommendation or two about the maintenance of my vehicle. He took it upon himself to even ride around in my car with me while I pointed out different concerns. I have already recommended him, and I look forward to actually seeing him in action in the future. I will be utilizing the services of "Your Mechanic" again.

Jamahl

20 years of experience
830 reviews
Jamahl
20 years of experience
Dodge Caravan - Car surges when air conditioning is on - Orlando, Florida
Jamahl was Professional, courteous, and friendly

Casime

12 years of experience
56 reviews
Casime
12 years of experience
Honda Accord - Car surges when air conditioning is on Inspection - Willingboro, New Jersey
Excellent customer service and is very knowledgeable. I recommend his services to everyone.

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