Engine RPM With A/C Running ??

[billt460]

Do any of you keep the engine revs down when you have your A/C pump running? I know the pumps are pretty much designed to operate within the RPM envelope of the engine.

But I refrain from pushing the revs too high, (4,000 RPM+), when I have the A/C running. If I stand on either my Jeep, or my Toyota, both will allow the engine to rev almost to the red line before shifting.

Has anyone experienced a pump failure from too much RPM? Or am I worried about nothing?

 

[Chris142]

Makes no difference. Last weekend we were coming home from AZ on 40 and the FJ engine revved to 5000 rpm on the hills. It was 110F.

 

[BrendanC]

Do any of you keep the engine revs down when you have your A/C pump running? I know the pumps are pretty much designed to operate within the RPM envelope of the engine.

But I refrain from pushing the revs too high, (4,000 RPM+), when I have the A/C running. If I stand on either my Jeep, or my Toyota, both will allow the engine to rev almost to the red line before shifting.

Has anyone experienced a pump failure from too much RPM? Or am I worried about nothing?

operating in OEM fashion, the AC Clutch will cut out at 100% throttle. i think it’s a non-issue with RPM. sure everything has a finite designed life rotation wise but i’ve never replaced a bad AC compressor on a personal vehicle due to failure and i drive at very high rpm frequently.

 

[Pew]

I drive a 4cyl crossover. I need the high RPMs to move anywhere when the AC is on

 

[Strumpan_]

it has a clutch so the ECM controlls it. I just drive like normal.

 

[fantastic]

I think on my Volvo it temporarily disengages the AC when under heavy throttle.

 

[K.Aoi]

You're paranoid.

 

[oldhp]

The ECU disengages clutch at predetermined RPM so the compressor won't blow up. Old systems used a high side pressure switch to cut off compressor. No worry's.

 

[eljefino]

Wouldn't a CCOT compressor "regear" itself to an appropriate output anyway? A regular clutched one would kick in and out as needed.

My cars work for me, so I won't change my behavior to be uncomfortable-- either temperature wise, or taking hills and merging safely.

My Saturns needed a good "blowing out" after a long traffic light-- the AC would barely keep up and would be at 100 percent through the first couple gears of accelleration. So I gave them the RPM to do that even at modest throttle.

 

[clinebarger]

I've seen Harrison V7 compressors blow up on 4th gen Camaros with built engines & power adders....It's very uncommon to have a issue with a stock vehicle!

 

[andrew_j]

Seems to me if AC compressor was out of range somehow they could easily disable the clutch.

 

[BMWTurboDzl]

Do any of you keep the engine revs down when you have your A/C pump running? I know the pumps are pretty much designed to operate within the RPM envelope of the engine.

But I refrain from pushing the revs too high, (4,000 RPM+), when I have the A/C running. If I stand on either my Jeep, or my Toyota, both will allow the engine to rev almost to the red line before shifting.

Has anyone experienced a pump failure from too much RPM? Or am I worried about nothing?

I'm "Nervous Nelly" just reving to 3k rpms.

 

[billt460]

I'm "Nervous Nelly" just reving to 3k rpms.

That's me as well. My 1991 Ford F-150 is still turning its original A/C pump after 34 years. But with the 4 speed automatic overdrive, it rarely gets to 3,000 RPM.

Most of these things are designed to provide satisfactory performance in low speed, low RPM city driving. I can't see where pushing them to the redline is going to help anything.

 

[Astro14]

In the old days (I’m thinking of my 1977 Olds 98), full throttle caused an interruption in the AC clutch voltage, so that the compressor was disengaged under full acceleration (and, ostensibly, high RPM).

The compressor on my Mercedes never disengages. The compressor is a variable displacement unit, so, the volume is varied, but it is always turning, always “engaged”.

If I were to adopt your philosophy, I could never rev the engine for fear of damaging the compressor.

That’s just needless worrying. The engine was built and tested to max RPM with the compressor engaged, because it is always engaged.

So, I just drive the car, and yes, once in a while, it sees full RPM. I don’t over-think this.

No worries.

 

[billt460]

In the old days (I’m thinking of my 1977 Olds 98), full throttle caused an interruption in the AC clutch voltage, so that the compressor was disengaged under full acceleration (and, ostensibly, high RPM).

The compressor on my Mercedes never disengages. The compressor is a variable displacement unit, so, the volume is varied, but it is always turning, always “engaged”.

If I were to adopt your philosophy, I could never rev the engine for fear of damaging the compressor.

That’s just needless worrying. The engine was built and tested to max RPM with the compressor engaged, because it is always engaged.

So, I just drive the car, and yes, once in a while, it sees full RPM. I don’t over-think this.

No worries.

So to be clear, the internals are always turning with the engine, regardless of the RPM, or the A/C being on or not. But when the air is "OFF" it just free wheels, without compressing anything? Much like a MDS system "deactivates" cylinders from producing power, but the pistons are still going up and down like normal.

 

[Astro14]

So to be clear, the internals are always turning with the engine, regardless of the RPM, or the A/C being on or not. But when the air is "OFF" it just free wheels, without compressing anything? Much like a MDS system "deactivates" cylinders from producing power, but the pistons are still going up and down like normal.

Close enough. Always turning. No clutch.

The internals are always turning and as the climate control asks for AC, the internal displacement varies to provide the level of cooling required.

 

[meep]

We had a Lexus for a while. It would downshift when the compressor kicked in to give it a few more rpm. That AC blew ice cold, and there was a solid mpg penalty. It favored comfort over mpg.

Everyone above has already covered it - oem design is baked in to protect the compressor. Enjoy the car!

 

[Nick1994]

Not me, and I don’t drive my Genesis too kindly. Though with twin-turbo torque and an 8 speed auto, it doesn’t spend much time with high RPMs.

The most aggravating thing was my grandma’s 2011 CRV. Taking it over 3k-4K RPMs (a requirement in that gutless car) turned off the A/C compressor. I was sweating bullets every time I drive it in the summer.

 

[Skippy722]

I'm "Nervous Nelly" just reving to 3k rpms.

That’s normal acceleration for me… the hemi starts sounding real good at about that. PCM/ECU is going to cut the clutch at a certain RPM so no worries…. And move the active runners in the intake if present, which is about 3500rpm in my truck.

Not me, and I don’t drive my Genesis too kindly. Though with twin-turbo torque and an 8 speed auto, it doesn’t spend much time with high RPMs.

The most aggravating thing was my grandma’s 2011 CRV. Taking it over 3k-4K RPMs (a requirement in that gutless car) turned off the A/C compressor. I was sweating bullets every time I drive it in the summer.

My Caliber was like that. 2.sl0w power baby!

 

[BMWTurboDzl]

That’s normal acceleration for me… the hemi starts sounding real good at about that. PCM/ECU is going to cut the clutch at a certain RPM so no worries…

I drive a 10 yr old BMW and I've been dreading the big bill so I'm trying to baby it untill I have to start commuting again and get a new car.