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Black the Darkside
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Discussion Starter #1
I've never been sure. On my previous cars it did turn off. Caddy FAQ says it should but it won't. Probably the reason we have an A/C shut off on the dash. This important info for our street racers as the A/C steals HP. So turn it off at the street lights when another potential race is at hand.:D

"Does the AC go off at full throttle?

Short answer: NO

Longer answer: No. The ECU is set to turn off the AC ABOVE 100% throttle and since you cant do that, then the AC does not turn off when you go full throttle."
 

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How can you tell if the AC is turning off or not under WOT? I'm not doubting what you say, but I'm curious how you can tell? I don't think status on the AC controls inside the car would neccessarily tell you the straight answer. If you're looking for every available horse, turn off the radio and any other electrical drain too since that will take power from the engine because of the alternator.

- Mark
 

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Discussion Starter #3
Mark VerMurlen said:
How can you tell if the AC is turning off or not under WOT? I'm not doubting what you say, but I'm curious how you can tell? I don't think status on the AC controls inside the car would neccessarily tell you the straight answer. If you're looking for every available horse, turn off the radio and any other electrical drain too since that will take power from the engine because of the alternator.
- Mark
On my previous cars you could feel it and you could hear it. It actually blew warm air. I don't feel this with the CTS and is why I'm inclined to believe the statements from the Caddy FAQ section.

I don't think any small electrical drains will affect performance. You could lighten your car and strip unnecessary parts.
 

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Mine shuts off at WOT. When you hook up a Tech2 and read the A/C off at WOT status, it will go from off to on when you floor it. This status will not be reflected on the climate control panel though.
 

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Discussion Starter #7
Mbai2 said:
Mine shuts off at WOT. When you hook up a Tech2 and read the A/C off at WOT status, it will go from off to on when you floor it.
You might wanna go to the FAQ section. It says it only goes off over 100% WOT which can't be accomplished. I know when I floor it it's still on. Glad in a way. I can manually shut it off if needed.


 

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RobertCTS said:
You might wanna go to the FAQ section. It says it only goes off over 100% WOT which can't be accomplished. I know when I floor it it's still on. Glad in a way. I can manually shut it off if needed.
Right...I read the FAQ. Maybe it's just the 5.7L ECM that has the bug. Or maybe it's the 3.2 Manual ECM that doesn't have the bug. I'm just stating that mine indeed shuts off and I know this because I can feel warmish air and I can see through the Tech2 that the ECM is requesting the A/C to be turned off when I am at WOT. There is an actual status output that says "A/C off at WOT" or something similar to that meaning that will change from off to on at WOT.
 

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Discussion Starter #9
Mbai2 said:
Right...I read the FAQ. Maybe it's just the 5.7L ECM that has the bug. Or maybe it's the 3.2 Manual ECM that doesn't have the bug. I'm just stating that mine indeed shuts off and I know this because I can feel warmish air and I can see through the Tech2 that the ECM is requesting the A/C to be turned off when I am at WOT. There is an actual status output that says "A/C off at WOT" or something similar to that meaning that will change from off to on at WOT.
Interesting! I agree you feel when an A/C kicks out by the warm air that follows. But I don't experience that now. You have a tech2 tool in your car?:holycrap:
Temp or permanent? Does the fan speed change any at WOT?
 

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You'd have to be at WOT for a LONG time to feel the AC blow warm air. Plus if you let up on the accel for a second the compressor kicks back in just long enough to recirculate refrigerant.
 

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Discussion Starter #11
jteolis said:
You'd have to be at WOT for a LONG time to feel the AC blow warm air. Plus if you let up on the accel for a second the compressor kicks back in just long enough to recirculate refrigerant.
JT,
I don't know what a "Long Time" is but in my test last night I went 40mph to 80 at WOT with my hand on the vent and experienced no change. Lets get member's feedback and have them test their cars at WOT and a hand on their vent and share their experience.
 

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I read recently that on Fords (project at work), the A/C clutch is disengaged at 85% throttle. I don't know if the V6 CTS is similar (A/C compressor parasitic loss would be a much bigger percent of total HP, than on the 400 HP V). This means the compressor drag will be temporarily eliminated. The blower should still blow, and cold air will come out for a while, since the evaporator still houses cold freon. WOT usually only lasts a few seconds (less than ~15 seconds even if your racing in the quarter mile!). Certainly not long enough for the vents to start blowing warm air.

Personally, if max HP counts (dyno run, street race, etc), I'd turn everything off (A/C, radio, and anything else that draws current), including TCS, which would engage the brakes when you brake loose the rear tires.

Maybe I have found the first use if my new PC based scan tool! I'm pretty sure that it reads A/C clutch engagement as part of the telemetry. I've also been meaning to test the 'virtual dyno' part of it.
 

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RobertCTS said:
JT,
I don't know what a "Long Time" is but in my test last night I went 40mph to 80 at WOT with my hand on the vent and experienced no change. Lets get member's feedback and have them test their cars at WOT and a hand on their vent and share their experience.
That's EXACTLY my point. The A/C cuts out only while you are at WOT, you'd HAVE to be at WOT LONG enough to feel the A/C blow warm air. Otherwise going from 40 to 80 isn't long enough to feel it blow warm air. It DOES cut out however. THEN when you relax the throttle the compressor goes back on....you'll never notice it was off in the first place.
 

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jteolis said:
That's EXACTLY my point. The A/C cuts out only while you are at WOT, you'd HAVE to be at WOT LONG enough to feel the A/C blow warm air. Otherwise going from 40 to 80 isn't long enough to feel it blow warm air. It DOES cut out however. THEN when you relax the throttle the compressor goes back on....you'll never notice it was off in the first place.
Agreed. I only feel it start to get warm halfway through my 0-top speed stints.
 

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Discussion Starter #15
What you guys say make sense. It appears the FAQ is incorrect. It appears some progress has been made in recent years. A few years ago I got almost instant warm air..like within 5 seconds. Thanks for answers guys!:D
 

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RobertCTS said:
What you guys say make sense. It appears the FAQ is incorrect. It appears some progress has been made in recent years. A few years ago I got almost instant warm air..like within 5 seconds. Thanks for answers guys!:D
Its easy enough to test. While driving around turn off the AC and see how long it takes to blow warm.
 

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Bob, I felt the same thing on my last vehicle, with the air warming whenever I punched it. Of course since it had no power, I had to punch it a lot. Stupid Fix Or Repair Daily.

Mbai2 said:
Agreed. I only feel it start to get warm halfway through my 0-top speed stints.
0-top speed, huh? So what is the top speed for the 03? I've been up to 120 a few times, but havent had many good opportunities to really stretch it out.
 

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I thought this was pretty standard, hell the 97 grand prixs had the clutch on the compressor disengage at WOT. so why not on the cts?
 

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Discussion Starter #19
Kael said:
I thought this was pretty standard, hell the 97 grand prixs had the clutch on the compressor disengage at WOT. so why not on the cts?
It was all based around a statement in the FAQ section that suggested it did not disengage. It's posted earlier in the thread.
 

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The compressor disengages for extra power, but if the engine doesn't need extra power (ie. the V8), it may be decided that it's not necessary to disengage.

The compressor on a modern car can be set to not only disengage at a certain throttle position, but also based on throttle *velocity* (rate of pedal position change). The CTS doesn't use this feature, but it does exist. I believe the V6 engines disengage at 100% throttle position with no time delay.

The time it takes to feel hot air would be directly dependent on the ambient temperature. If it's hotter outside, you'll feel it right away. Cooler weather will take much longer.
 
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