AC and Engine Revs
Thread Starter
Driver School Candidate
Joined: Apr 2010
Posts: 33
Likes: 1
From: BC
AC and Engine Revs
I only use AC in the summer around here, not year 'round. When I turn it on, I notice that the engine revs higher when turning the compressor, which cycles on and off. It's only a few hundred RPM, but it's quite noticeable and will make the truck surge forward when sitting at a traffic light. The dealer says this is how the AC works on a GX, so I've gotten used to it.
Has anyone else had this issue?
Has anyone else had this issue?
Thread Starter
Driver School Candidate
Joined: Apr 2010
Posts: 33
Likes: 1
From: BC
That's what I thought, but it's a brutish, un-Lexus like solution to me. I have other vehicles where the AC operation is unnoticeable: an 04 Sienna, an 07 G35X, even my recently departed 08 VW EOS. Oh well.
Instructor
Joined: Apr 2006
Posts: 1,213
Likes: 67
From: EARTH
It is absolutely normal, what exactly happen when the Engine is idle at normal stance, the signal generated by the ECU ensure constant flow of Air volume which is passing the closed throttle valves, When the AC is switch on, the ECU detects this sudden load, and adjust the Idle Speed Control based on the signals received, and increases the flow to stabilize the curb idle, when loads are applied to the engine. You will also see the following RPM increase at the following conditions, One is Electrical Load, Fast Idle,AT Load.
Lead Lap
Joined: Sep 2008
Posts: 721
Likes: 3
From: CA
It is absolutely normal, what exactly happen when the Engine is idle at normal stance, the signal generated by the ECU ensure constant flow of Air volume which is passing the closed throttle valves, When the AC is switch on, the ECU detects this sudden load, and adjust the Idle Speed Control based on the signals received, and increases the flow to stabilize the curb idle, when loads are applied to the engine. You will also see the following RPM increase at the following conditions, One is Electrical Load, Fast Idle,AT Load.
Turby
Driver School Candidate
Joined: May 2010
Posts: 3
Likes: 0
From: MO
While driving with the A/C on (doesn't matter what setting, auto, fresh, recirc, etc), does anyone notice the engine power surging when the compressor turns on/off.
For example, when cruising on the highway, I can feel the power reduced when the compressor kicks on, then about 15 seconds later when it kicks off, I can feel the power return to normal. This cycle repeats over and over again in 15-30 second intervals.
I have been to the dealership 4 times, once they replaced the condenser fan, but that did not help. I took it back for the 4th time and they said that all GX's do this and it is normal. Funny, I had a loaner RX350 and you could not feel anything with the AC running. They told me they drove a 2009 GX on the lot and it did the same thing.
It just seems odd to me that this would be normal. I drive around 50 rental cars a year and have never noticed this with the rental or on any of the other 17 cars I have owned.
I have also felt the surge while stopping, but to feel this while cruising down the highway. On/off/on/off and having to adjust the throttle to compensate does not seem "normal" to me.
For example, when cruising on the highway, I can feel the power reduced when the compressor kicks on, then about 15 seconds later when it kicks off, I can feel the power return to normal. This cycle repeats over and over again in 15-30 second intervals.
I have been to the dealership 4 times, once they replaced the condenser fan, but that did not help. I took it back for the 4th time and they said that all GX's do this and it is normal. Funny, I had a loaner RX350 and you could not feel anything with the AC running. They told me they drove a 2009 GX on the lot and it did the same thing.
It just seems odd to me that this would be normal. I drive around 50 rental cars a year and have never noticed this with the rental or on any of the other 17 cars I have owned.
I have also felt the surge while stopping, but to feel this while cruising down the highway. On/off/on/off and having to adjust the throttle to compensate does not seem "normal" to me.
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Thread Starter
Driver School Candidate
Joined: Apr 2010
Posts: 33
Likes: 1
From: BC
I've had the same experieince while on the highway as well. And it doesn't seem to happen on any of the loaner cars Lexus provides, or any of the other cars I've owned, including a 2004 LS430. So we're in full agreement on this.
It just seems very un-Lexus like to me, but my dealer has told me this is normal for a GX470, so I'll have to live with it. (Maybe the engineers who developed the AC system were the same geniuses who also forgot to add a "mist" feature to the windshield wipers!)
It just seems very un-Lexus like to me, but my dealer has told me this is normal for a GX470, so I'll have to live with it. (Maybe the engineers who developed the AC system were the same geniuses who also forgot to add a "mist" feature to the windshield wipers!)
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Racer
Joined: Mar 2004
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From: Colorado
Ha ha! Yeah, this thread is 4 years old, and the original poster is likely long gone, seeing that he only did 5 posts.... So I have to say, is he for real? ALL cars idle up when the A/C goes on, if anything, i would be concerned if it DIDN'T idle up...
The only car i own that doesn't do that is my 75' Cadillac, because it's got an 8.2 liter V8 and it doesn't need to idle up to compensate.
The only car i own that doesn't do that is my 75' Cadillac, because it's got an 8.2 liter V8 and it doesn't need to idle up to compensate.
Lexus Champion
Joined: Dec 2008
Posts: 1,714
Likes: 22
From: VA
It is absolutely normal, what exactly happen when the Engine is idle at normal stance, the signal generated by the ECU ensure constant flow of Air volume which is passing the closed throttle valves, When the AC is switch on, the ECU detects this sudden load, and adjust the Idle Speed Control based on the signals received, and increases the flow to stabilize the curb idle, when loads are applied to the engine. You will also see the following RPM increase at the following conditions, One is Electrical Load, Fast Idle,AT Load.
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