Do car air conditioners still decrease engine power?

[Sheepathon]

Someone told me they came up with some kinda compressor cutoff in 1998 or something, I'm not sure.

 

The compressor is still powered directly from the engine.

 

[Evadman]

Whoever that someone is is stupid. That someone is probably revering to a CCOT system, which still uses engine power.

 

[Eli]

Absolutely.

Where do you think the energy comes from?

I'd imagine that they've made them more efficient over the years, but I'm sure they still sap at least 1-2HP.

 

[Zenmervolt]

If the compressor is running, it necessarily saps engine power. The "compressor cutoff" just disengages the compressor clutch at WOT (Wide Open Throttle) because the assumption is that you will want maximum power when the throttle pedal is floored.

ZV

 

[TitanDiddly]

Rumor has it that Geo Metros can't accelerate onto the highway with the AC running.

 

[J0hnny]

Originally posted by: PhasmatisNox
Rumor has it that Geo Metros can't accelerate onto the highway with the AC running.

Most econo-box / small cars can't accelerate as fast w/ AC on.

 

[Eli]

LOL...

I have a hard time imagining an A/C using more than 2 or 3HP.. I mean, it's not like they're large units.. they aren't cooling a large area.

Aren't most small window A/C units' motors in the 3/4 - 1HP range?

 

[m2kewl]

Originally posted by: Zenmervolt
If the compressor is running, it necessarily saps engine power. The "compressor cutoff" just disengages the compressor clutch at WOT (Wide Open Throttle) because the assumption is that you will want maximum power when the throttle pedal is floored.

ZV

ding ding, right again!

 

[murphy55d]

I have a pseudo-ricer friend who tells me it takes away 10-15hp when you run the A/C.

BTW, he drives a Probe and plans to enter it into a "Battle of the Imports", because it supposedly classifies as an import due to some sort of Ford/Mazda arrangement. 😕

 

[Linux23]

Originally posted by: Zenmervolt
If the compressor is running, it necessarily saps engine power. The "compressor cutoff" just disengages the compressor clutch at WOT (Wide Open Throttle) because the assumption is that you will want maximum power when the throttle pedal is floored.

ZV

 

[puffpio]

Do alternators have a clutch in them like the A/C? So the alternator would turn off on wide open throttle leaving the car running off the battery for that time. That way we would gain even more power

 

[Tremulant]

I know I feel a power loss in my Focus when I have the A/C on but I can't live without it, it's too hot.

 

[Perknose]

Originally posted by: murphy55d
I have a pseudo-ricer friend who tells me it takes away 10-15hp when you run the A/C.

BTW, he drives a Probe and plans to enter it into a "Battle of the Imports", because it supposedly classifies as an import due to some sort of Ford/Mazda arrangement. 😕

They are Mazdas!

 

[Ausm]

Originally posted by: pio!pio!
Do alternators have a clutch in them like the A/C? So the alternator would turn off on wide open throttle leaving the car running off the battery for that time. That way we would gain even more power

Not that I am aware of.

Ausm

 

[iamwiz82]

Originally posted by: pio!pio!
Do alternators have a clutch in them like the A/C? So the alternator would turn off on wide open throttle leaving the car running off the battery for that time. That way we would gain even more power

No, however I have known people to put in a smaller belt bypassing the alternator and power steering for drag racing.

 

[Zenmervolt]

Originally posted by: pio!pio!
Do alternators have a clutch in them like the A/C? So the alternator would turn off on wide open throttle leaving the car running off the battery for that time. That way we would gain even more power

No. The power put out by the alternator is absolutely critical to keeping an engine running properly especially at WOT. Also, the alternator spins much more freely than the A/C compressor.

As for the HP loss, it's definitely less than 5 HP. The big problem is that the compressor has a lot of resistance to an increase in its rotary speed. In other words, while it only takes a couple horsepower to run the A/C compressor, it is much harder to accelerate the A/C compressor, which is why it feels as though you're losing more than a couple HP.

ZV

EDIT: The alternator comment referrs to a stock engine. If you have your car set up for drag racing, then you'll be making sure that you have the battery set up specially to handle the engine's electrical demands and you will be more careful about the use of electrical accessories. It's not a good idea to do in street use.