# car slow down when i turn a/c



## Gabe86 (Jun 18, 2019)

So i recently have my car spark plugs change. i have notice my car drink up my gas. Im sure it me or if my mind is playing trick with me. So i have started to point out some thing what could it be. Since im in texas the temp be around 99 to 104 lately. When i drive and have my a/c on i do feel like my car has some kind of resistance. But when i turn it off my car feel like it drive a little more different. There not much resistance when press the gas. What could it be ? 

please keep it simple. im no mechanic or konw anythign about car.


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## John Smith_inFL (Jun 15, 2018)

do you have a 4 cylinder Fiat - or - a big 8 cylinder Chevy Suburban ??


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## Gabe86 (Jun 18, 2019)

i have a 4 cylinder nissan sentra 2012 is the type that you have to remove the intake just to replace the spark plugs


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## Nealtw (Jun 22, 2017)

The AC unit does use power from the engine, you may not notice in bigger cars with more powerful engines and using AC does add to the fuel bill.


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## Gabe86 (Jun 18, 2019)

Nealtw said:


> The AC unit does use power from the engine, you may not notice in bigger cars with more powerful engines and using AC does add to the fuel bill.


okay ? so then what could it be then ?


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## Nealtw (Jun 22, 2017)

Gabe86 said:


> okay ? so then what could it be then ?


Any time you turn on anything AC or all the lights, you will use some of the power for that instead of driving power and it will use more gas.


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## Oso954 (Jun 23, 2012)

Is this occurring at low rpm ? Do you have the Continuously Variable Transmission? (CVT)

If you are putting along with little pressure on the gas pedal, the CVT is selecting a ratio to save gas by using as little hp as possible to maintain speed. When the a/c kicks in, it’s adding 2-5 hp on top of whatever HP you were using. It will slow the car until you add gas by depressing the pedal. If you have cruise control and are using it, it might adjust for it automatically.

When the car reaches the set temp, the compressor will kick off and then later will kick back in as the temp rises again. In some cars it is noticeable by sensitive drivers. Others don’t noticing because they don’t pay attention, or because they are lead footing it a bit and driving around at higher power settings and/or using lower gear ratios (higher rpms) while driving the same car/same route you do.


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## Gabe86 (Jun 18, 2019)

Oso954 said:


> Is this occurring at low rpm ? Do you have the Continuously Variable Transmission? (CVT)
> 
> If you are putting along with little pressure on the gas pedal, the CVT is selecting a ratio to save gas by using as little hp as possible to maintain speed. When the a/c kicks in, it’s adding 2-5 hp on top of whatever HP you were using. It will slow the car until you add gas by depressing the pedal. If you have cruise control and are using it, it might adjust for it automatically.
> 
> When the car reaches the set temp, the compressor will kick off and then later will kick back in as the temp rises again. In some cars it is noticeable by sensitive drivers. Others don’t noticing because they don’t pay attention, or because they are lead footing it a bit and driving around at higher power settings and/or using lower gear ratios (higher rpms) while driving the same car/same route you do.


So your basically saying this is normal? If so why isn't that I'm now noticing this ?


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## pumpkin11 (Oct 31, 2020)

Your engine turns a belt, or in some cases multiple belts,

These belts turn pulleys on accessories such as alternator, water pump, power steering, A/C

Each one of these pulleys takes power from the engine to turn,

Let's say just for talk sake each one of these pulleys takes 5hp to turn,

When your A/C is turned off, that 5hp is going to your wheels, when you turn your A/C on, it is taking that 5hp away from your wheels to turn the A/C compressor, so your wheels have less power,

In vehicles with high hp and big engines you probably won't notice any difference,

It is more noticeable in small engines with low hp


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## Gabe86 (Jun 18, 2019)

Would *ARCTIC FREEZE *be good idea. I just bring this up. Because it doesn't give out cool air. So could it be working twice as much ( car rpm )


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## LawrenceS (Oct 21, 2020)

This isn't something we are going to be able to figure out over an internet forum. For all we know your compressor could be binding robbing the engine of power trying to turn it or your evap is clogged causing excess pressure. Your best bet would be finding a local mechanic you can trust. You could also try to look on nissan specific forums to see if there are any trending issues.


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## turbo4 (Jan 30, 2021)

I can feel the power difference in some of my cars with the AC on. The smaller engine ones. Not so much in the Camaro SS with over 400HP.


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## Bob Sanders (Nov 10, 2013)

Gabe86 said:


> Would *ARCTIC FREEZE *be good idea. I just bring this up. Because it doesn't give out cool air. So could it be working twice as much ( car rpm )


No. You can not mix and match refrigerants. If you wish to use a different refrigerant, then the system must be completely evacuated and recharged. The refrigerant used also must be compatible with the refrigerant oil in your ac system.

If your ac is not blowing cool air and is adding additional drag which wasn't there before, then clearly there is a problem with the ac and it needs to be looked at. If ac charge is low for example, the ac will run for longer periods thereby drinking more gas and adding more drag. In any event, continued use of the ac under these circumstances will result in more damage and possibly a burned up ac compressor. Stop using the ac until it gets looked at.


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## LawrenceS (Oct 21, 2020)

Bob Sanders said:


> No. You can not mix and match refrigerants. If you wish to use a different refrigerant, then the system must be completely evacuated and recharged. The refrigerant used also must be compatible with the refrigerant oil in your ac system.
> 
> If your ac is not blowing cool air and is adding additional drag which wasn't there before, then clearly there is a problem with the ac and it needs to be looked at. If ac charge is low for example, the ac will run for longer periods thereby drinking more gas and adding more drag. In any event, continued use of the ac under these circumstances will result in more damage and possibly a burned up ac compressor. Stop using the ac until it gets looked at.


Arctic Freeze is just a brand name of a can of r134a from a parts store. I wouldn't suggest ever using cans of r134a though. The only way to service a/c would be a full evac, then vacuum, then filling it to spec with scales. Otherwise who knows how much is currently in the system or if there is air/moisture in it. Overcharge/undercharge/air/moisture all cause a/c systems to not function properly. Plus if it's undercharged there is probably a leak that needs to be found. If the charge is good and it still doesn't work you then need gauges or a all in one machine to check pressure's and see what is happening.


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## Old Thomas (Nov 28, 2019)

Your engine is barely big enough to propel the car. AC takes power making it slower.


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## papereater (Sep 16, 2016)

A 2012 vehicle has R134a in it. No worry to mismatching, and R12 vehicles mostly have been long gone (last to have R12 from factory were about 1994). Only other refrigerant compatible which is not R134a is ES-12, a mixture of straight chain HC's (hydrocarbons, mostly propane and isobutane).

You really dont have to do a "full vac" to charge. I have done this many many times, BUT you must first diagnose with BOTH ac guages, high and low psi sides. Then, determine psi needed. There will be slight difference depending on humidity/temp but not a big deal. And a can will work. I usually add one to get it cold. This is not astrophysics, but one must know first how to interpret guage readings!

Warning: do not simply ad refrigerant hoping/wishing/praying it will fix your ac problem without diagnosing.


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## papereater (Sep 16, 2016)

A good range for psi varies, but 30 min to about 40 is adequate at 90 Deg F. High side, about 2x ambient temp F plus 50, but varies.


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## quatsch (Feb 4, 2021)

Oso954 said:


> 2-5 hp on top of whatever HP you were using.


I've heard 7 hp.


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## Gabe86 (Jun 18, 2019)

What i going to do is put a fuel injector cleaner. After looking online. even if my air off or on. I still cant recall how much gas my car is using lately. After me and my cousin change out the spark plugs. And he told me to turn on the car. it wouldnt come one. And realize he forgot to connect the small hose/tube that was not connected from the back. So i started to think it might has some carbon build up inside. or the air intake sensor needs cleaning. Rather then just buy mass airtake cleaner. i rather use this.


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## papereater (Sep 16, 2016)

Dont expect much from that excersise. gasoline already has solvents that keep your injectors clean. It is a waste of $.


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