fbfisher

So it seems that Porsche engineers are fans of Star Trek...

Captain Kirk (me) says "I'm coming out of the apex, I need more power, take me to full warp" and Scotty (the computer that manages the car's systems) say's "but captain, I'm give'n it all she's got, the only way I can git chew more power it to start shutt'n down the climate control, and if I do that, it's gonna get hot in here (sounds better if you can read with a Scottish accent.) Captain Kirk says, "Scotty, I've got to have more power" as the Captain keeps his foot planted, and the warp drive begins to howl as it spins up toward 6,000 RPM. Scotty, eager to please the Captain, shuts down the A/C compressor so that max power is available. The Captain, seeing the next curve ahead, gives the command to "take us out of warp" and Scotty, reengages the A/C compressor...

Thinking this was some kind of malfunction, I took the car in to the dealer to be checked. Apparently, our cars were designed so that when max power is called upon (sustained WOT), the A/C compressor is temporarily shut down.

This may be common knowledge, but I had never seen it discussed here, so I figured I'd post. Now I'm just waiting for one of you to tell me that the service manager and the tech who read me the description from some Porsche manual are FOS.

chris.hanle

I didnt know that, but I am no expert. I do think its cool though, well not so cool on a hot summer day.

Dadio

All modern cars do this. Next time you drive your wifes SUV, or any other car built in the 10 years or so, mash down on the gas pedal and see what happens to the AC .

Hatzenbach

That is so cool (literally) because that means I can leave the A/C on when driving on the track :-)

808c2s

True dat!

Misdirection

I actually inadvertently did that last weekend and didn't notice until I was doing my cool-down lap No cold air until that point, presumably due to the aforementioned design feature.

Anybody know if it's designed this way just in order to provide more power upon request, or is this somehow to minimize stress on the A/C system's parts? Is it tied to the throttle, or is it tied to the RPM?

fbfisher

^ I was told that it is related to WOT, not RPM.

SToronto

Curious to try this...

golftime

Been around for many 15-20 years, or maybe even more. In the older cars it was tripped by engine vacuum (directly related to throttle position) but I have to believe it is all electronics today. I seem to recall it was implemented sometime after emissions controls zapped all the horsepower years ago, and car manufacturers were trying to compensate under full throttle condition.

Michael1

Not true. I have driven loads of new cars (2013) that do not do this (can't speak for the SUVs). The only ones I have seen do this, other than the one reported by the OP, are underpowered 4 cylinder cars, that need all the squirrels sending power to the front wheels.

Why Porsche did this on a 408 horsepower car is baffling to me.

Michael

fbfisher

Alan C.

I doubt the compressor is designed for much use in the 6000 rpm range.

sjfehr

I had to do this manually on my woefully underpowered 3.4L V6 Camaro. It was very noticeable difference, and was NOT automatic. If I had a passenger, I'd cry out "Engaging super turbo boost!" and reach up and turn off the AC before merging onto the highway and such.

Devil Boy

I do the same thing in my 4-cyl Chevy S-10...except for calling out "engaging super turbo boost!"