27 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHAir Conditioning Sucks Power
Leading reported evidence
Check any fan stage errors and found none recorded
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Read evidence and context
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Performed · outcome unconfirmed
The tech checked for any fan stage errors and found none recorded but did find the fan motor was drawing a lot more current than the other side's fan motor.
Leading evidence: 'Check any fan stage errors and found none recorded' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check any fan stage errors and found none recorded' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion · Original poster
All kidding aside, my car drives and feels significantly different when running the AC.
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Suggestion
Anyone know if the car will run the compressor for this purpose, even if the HVAC controls are off?
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Suggestion
For those of you that wanna be hardcore like me, just run the fan on high with the windows down and get some vent clip mounted cup holders with cups of ice on all the vents.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check any fan stage errors and found none recorded
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
The tech checked for any fan stage errors and found none recorded but did find the fan motor was drawing a lot more current than the other side's fan motor.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
For those of you that wanna be hardcore like me, just run the fan on high with the windows down and get some vent clip mounted cup holders with cups of ice on all the vents.
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27 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Outcome without a verified action link
just drove my C4S home from SF calif 2 weeks ago in 100-108 degree weather thru redding calif and noticed no difference in power pull at all - 2 days of extremely hot weather with A/C on - i think you have another issue going on
Anyone else avoid using the AC because it sucks the power and make the shifting rougher ? It might not be noticeable to those who don't drive it daily, but I sure do.
Hardly notice the parasitic load on my 2.7l Boxster.
I think something else is going on.
Just a WAG, but have you done an E-Gas calibration recently? Procedure is in the owners manual.
(For my cars without touching the gas pedal turn the key on and leave on for 1 minute. Then turn the key off and leave off for 10 seconds. Done. The times don't have to be exact but they can't be less than the numbers given. IOWs, leaving the key on for 65 seconds is ok. Leaving it on for just 55 seconds is not ok.)
Also, if you haven't had it done in a while do a brake/clutch fluid flush bleed. I had this done -- it was overdue -- for my Boxster a few months back and the clutch action and shift action improvement was remarkable.
After I get used to how my vehicles "feel", I can usually detect when the A/C clutch kicks in. Just barely.
But the few HP that the A/C consumes does not affect the performance in any real way.
I agree with Macster that there must be some other issue(s) with your particular car.
Typically an engine's ECU will compensate for the A/C load by increasing the throttle position very slightly when the A/C clutch engages and will then reduce the throttle position when the clutch disengages.
If this did not occur, a person would notice the reduced RPMs, and the engine may even bog down or die. Likewise when the A/C clutch disengages the engine would surge.
Perhaps there is a problem with the switch/sensor in your A/C system that the ECU relies upon for this info.
Interesting, I have definitely been noticing it on mine as well. Will have do try the calibration as suggested above and mine is due for fluid flushes anyway so need to get that done soon as well.
just drove my C4S home from SF calif 2 weeks ago in 100-108 degree weather thru redding calif and noticed no difference in power pull at all - 2 days of extremely hot weather with A/C on - i think you have another issue going on
I don't think it's an EGas calibration issue, since I don't believe the 99's had EGas, it was introduced in either 2000 or 2001 if I recall reading correctly.
Yep mine too. Pulls way harder and smoother with the AC off. I have tried all the tricks I just think it robs noticeable power. Back in my eagle talon days AC on at the drag strip cost ya 3 tenths.
oh come on. significant parasitic drag? Unless you have a completely botched compressor, it costs no more than say 10bhp to drive the compressor (and thats being generous). If 10bhp is turning a dog into a sideways tire roaster, I'd be shocked. I think you're exaggerating. Either that or you have a more serious problem.
I agree with this however, I think some have a more sensitive butt dyno than others and while hp might be negligible, I think what some are actually describing is the response off the line or in stop and go traffic.
For those of you that wanna be hardcore like me, just run the fan on high with the windows down and get some vent clip mounted cup holders with cups of ice on all the vents. Old school AC.
Or if you need the heavy duty version...
Yes, of course. I assumed (apparently incorrectly) we were talking about a car equipped with E-Gas.
While I don't have the numbers recorded my Boxster's A/C system in maintain cabin temperature mode -- that is not blasting arctic to cool down an overheated cabin -- requires less than 1hp at idle. This is based on monitoring engine load -- via the OBD2 port and using a hand held OBD2 code reader/data viewer -- in "real time".
Now occasionally my Boxster appears to get into a perfect storm with the A/C on and while not running full blast still working to bring down the cabin temperature and with the radiator fans on (naturally) (and maybe on high) the engine compartment fan kicks on.
The engine, at idle, begins to labor some. I have not had the OBD2 code reader handy to view engine load at this time. I do not believe this is a problem with the A/C system. I worry more it is either a sign of a battery wearing out -- though the battery does not give any of the typical signs of pending trouble -- or a sign the alternator is getting tired. The alternator is original equipment and the car now has just under 292K miles on it. Other owners have had alternators go out in fewer miles...
All kidding aside, my car drives and feels significantly different when running the AC. The shifting is rougher, and the acceleration is noticeably slower. I agree with 300hp on a car this size you wouldn't think it would matter or be noticeable, but it is. I wonder how much hp the air compressor uses and is this something that could work its way out of whack over the years ? It is after all a '99.
Yes while that is hp but these cars weren't known for torque... Maybe the ac running without remapping is tipping the scale enough to the sluggish side?
Just thinking out loud.
On a hot day or at higher altitude, I can always feel the power difference between having the AC on or off.
I've never been certain if disabling the compressor using the dash controls means that the fuel cooler is not working. Anyone know if the car will run the compressor for this purpose, even if the HVAC controls are off? I don't think it really matters, since on the 3.4 cars it only cools the fuel returning to the tank, but still curious...
The A/C compressor is not engaged when the snow flake symbol is dark. The only time the fuel cooler -- my 996 Turbo has one I'm not sure the NA 996 cars come with one -- is actively cooling fuel is when the A/C is on.
The 3.4 996's all came equipped with fuel coolers, but it only cools return fuel, which I believe is different than how the turbo fuel cooler is plumbed.
You can reduce the overall load of the A/C by setting it to the recirc, max cooling, and using the blower speed control to regulate cabin comfort.
That bypasses the "re-heating" of the chilled airflow, lower compressor duty cycle, lower pre-heat of the radiator cooling airflow.
Just so it is clear while it is my experience the A/C system is not a power draining accessory load if you feel the A/C system is affecting power in some way you should have this checked out by someone who is very familiar with these cars in order to know if what you are experiencing is just normal or there's something going on.
Once a radiator fan on my Turbo wasn't putting out nearly the same amount of air the other radiator fan was. The fan was running, to be sure, but the air flow from the back of the fan was very low.
The tech checked for any fan stage errors and found none recorded but did find the fan motor was drawing a lot more current than the other side's fan motor. While this was not affecting the engine any it does bring up the possibility in your car's case there is something else going on that is putting a larger load on the engine, from possibly the alternator having to produce much more electrical power to satisfy the demands of a malfunctioning radiator fan motor, for instance.
Just a follow up of sorts.
As I touched upon in a previous post to this thread I had noticed my Boxster seemingly laboring a bit at idle with the A/C on and the engine compartment fan running.
Well, yesterday AM when I went start the engine the battery was dead. It was "fine" the day before when I was using the car.
Besides the laboring I mentioned above the starter did seem to be cranking the engine a bit slower. Not by a lot just slower enough to notice and to prompt me to wonder what it meant besides possibly possessing an over active imagination.
Well, now I know.
My point in this update is if you feel the engine is down on power a bit, the engine is laboring a bit, before you condemn the A/C think about perhaps the battery going bad and as a result the alternator is working overtime to not only satisfy the car's electrical needs but also to feed the appetite of a battery on its way out.
I'm sure that to some degree "Air Conditioning Sucks Power", but not having air conditioning in Mississippi in the summer sucks worse. For the last few weeks it's been 95-101 degrees with 75% humidity.
