# 2005 Honda Civic Sdn - Does AC drag on a car engine? **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** honda\ **Created:** [June 6, 2020, 4:38pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402 "2020-06-06T16:38:13Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Donny11](https://avatars.discourse-cdn.com/v4/letter/d/7ba0ec/32.png) [@Donny11](https://community.cartalk.com/u/Donny11)\ **Post date:** [June 6, 2020, 4:38pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/1 "2020-06-06T16:38:13Z")
A friend of mine leaves his air-conditioning on all the time whether he needs it or not and even if he’s going up a mountain punching the gas and wondering why he doesn’t have much acceleration I told him I think putting the a/c drags on the engine a little bit is it true or not? ---
**Author:** ![GorehamJ](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/gorehamj/32/24103_2.png) [@GorehamJ](https://community.cartalk.com/u/GorehamJ)\ **Post date:** [June 6, 2020, 5:11pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/2 "2020-06-06T17:11:49Z")
Yes. It is true that AC reduces power somewhat in almost all vehicles. The amount one notices it varies pretty widely from model to model. ---
**Author:** ![vipergg](https://avatars.discourse-cdn.com/v4/letter/v/50afbb/32.png) [@vipergg](https://community.cartalk.com/u/vipergg)\ **Post date:** [June 6, 2020, 5:22pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/3 "2020-06-06T17:22:25Z")
Yes it does and you will notice it a lot more in smaller 4 cylinder engines like Civic uses. It is a lot less noticeable in V6 and V8 engines . ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [June 6, 2020, 5:24pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/4 "2020-06-06T17:24:15Z")
An AC compressor draws about 5 H.P. from the engine. Tester ---
**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\ **Post date:** [June 6, 2020, 5:56pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/5 "2020-06-06T17:56:25Z")
In the olden days, I remember a comedian saying, the brakes are so bad, and the engines so under powered if you need to make an emergency stop, turn on the AC. I have not personally experienced any issue with AC negatively affecting vehicle performance to the point I was concerned. ---
**Author:** ![shanonia](https://avatars.discourse-cdn.com/v4/letter/s/9de053/32.png) [@shanonia](https://community.cartalk.com/u/shanonia)\ **Post date:** [June 6, 2020, 6:35pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/6 "2020-06-06T18:35:01Z")
I can feel it, subtly, kick in and out on my 1999 Civic, especially when giving it a lot of throttle. I think when you floor it the computer prevents the compressor from cycling on, so you don’t have that HP loss when you are calling for max power. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [June 6, 2020, 7:00pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/7 "2020-06-06T19:00:44Z")
Back in the day I added a vacuum actuated switch to my 1981 Accord that would disconnect the AC compressor under heavy throttle. With 76 HP there was little to spare on the highway. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [June 6, 2020, 7:14pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/8 "2020-06-06T19:14:03Z")
Many smaller cars back in the day had switches and so on that would cut the power to the compressor when the throttle was mashed hard. The first SAAB I owned was an absolute dog with an automatic trans and naturally aspirated. In the CO mountains it really struggled even with the A/C off. A 116 Horsepower on a near 2 ton car in altitude could have used an hourglass instead of a speedo. ---
**Author:** ![davepsinbox\_157004](https://avatars.discourse-cdn.com/v4/letter/d/73ab20/32.png) [@davepsinbox\_157004](https://community.cartalk.com/u/davepsinbox_157004)\ **Post date:** [June 6, 2020, 10:24pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/9 "2020-06-06T22:24:26Z")
> [@Tester](#): > > An AC compressor draws about 5 H.P. from the engine. I read 8hp years ago in a car magazine. 5hp sounds about right for newer vehicles. Since the base engine in a 2005 Civic produces 115hp the difference is probably noticeable. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [June 7, 2020, 3:32am UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/10 "2020-06-07T03:32:06Z")
Chrysler products for years automatically disconnected the A/C at full throttle only letting it function again when the vacuum came back up. Don’t know if they still do. The newest Chrysler product I owned was an 04. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [June 7, 2020, 3:46am UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/11 "2020-06-07T03:46:06Z")
> [@davepsinbox\_157004](#): > > Since the base engine in a 2005 Civic produces 115hp the difference is probably noticeable. And less than half of that horsepower @ 3000 RPMs in high gear. Twenty-five years ago I used to see Hondas crawling along in the truck lane while going up mountain grades. I had a 1988 four cylinder Dodge with a 100 horsepower engine but with the larger displacement engine I was able to climb those grades @ 60 MPH with the A/C off. > [@oldtimer-11](#): > > Chrysler products for years automatically disconnected the A/C at full throttle only letting it function again when the vacuum came back up. The PCM disengages the clutch at 80% throttle or higher, nothing to do with vacuum. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [June 7, 2020, 4:26am UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/12 "2020-06-07T04:26:45Z")
Chrysler cars were disabling the A/C long before the cars had PCMs. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [June 7, 2020, 4:35am UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/13 "2020-06-07T04:35:01Z")
I remember those commercials, as well but as I recall, they were made in a time when junky econoboxes had barely 60hp, if that ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [June 7, 2020, 4:47am UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/14 "2020-06-07T04:47:04Z")
Carbureted cars of the late 1970’s, early 1980’s had a full throttle cut-out switch, that was for a short period of time, fuel injection was phased in from 1983 to 1990 on Chrysler vehicles. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [June 7, 2020, 1:52pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/15 "2020-06-07T13:52:50Z")
Simple test for the OP’s friend: next time they’re going up a mountain pass and feel a lack of power, turn off the a/c and see if it makes a significant difference. Could just be a combination of low hp and altitude causing the poor performance. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [June 7, 2020, 2:13pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/16 "2020-06-07T14:13:49Z")
Imagine the horsepower one of those old GM A6 compressors would eat up. Many years ago I was reading a Hot Rod mag or something similar and they did a dyno test on a Chevy 350. They said the engine gained 7 horses by simply removing the mechanical fan blade. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [June 7, 2020, 3:12pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/17 "2020-06-07T15:12:22Z")
How did the chrtsler cars of the mid 50s to 1970 handle it? ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [June 7, 2020, 6:19pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/18 "2020-06-07T18:19:52Z")
There was a switch on the throttle linkage, IIRC. ---
**Author:** ![PhantomPatriot](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/phantompatriot/32/20713_2.png) [@PhantomPatriot](https://community.cartalk.com/u/PhantomPatriot)\ **Post date:** [June 7, 2020, 6:50pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/19 "2020-06-07T18:50:39Z")
I own a 2005 Ford Explorer with the 4.0L V6. With a new belt, pulley, and tensioner, the air conditioning increases the engine load _at idle_ by approxmiately 15%. I had wondered about this for a while and performed some basic and unscientific tests in my driveway in the fall using a wifi-based OBDII dongle. These values will vary based on vehicle, environmental conditions, and a variety of other factors which I cannot begin to scratch the surface of. Ballpark value I can give you is 15% based on my experience. The number is likely to be higher (by how much, I have no idea) with your vehicle. ---
**Author:** ![davepsinbox\_157004](https://avatars.discourse-cdn.com/v4/letter/d/73ab20/32.png) [@davepsinbox\_157004](https://community.cartalk.com/u/davepsinbox_157004)\ **Post date:** [June 7, 2020, 8:37pm UTC](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402/20 "2020-06-07T20:37:42Z")
> [@Nevada\_545](#): > > And less than half of that horsepower @ 3000 RPMs in high gear. Possibly less than that. My '09 Corolla ticks over at about 2400rpm at 60mph on level pavement. Let’s keep it simple and say our theoretical '05 Civic is putting out 45hp at 60mph. Subtract the 5hp drag from the A/C and you’ve lost 11% of available power. That would be noticeable. [Next page](https://community.cartalk.com/t/2005-honda-civic-sdn-does-ac-drag-on-a-car-engine/165402.md?page=2)