To AC or not to AC
05-23-13, 06:38 AM
#31
Driver
I've got to agree with Cruiter. The system works fine, so why bemoan the lack of a button? I have an a/c button in my Mercedes - I've never used it.
I think the last time I used an a/c button was in my 1977 Audi - the compressor was so powerful you could feel the car decelerate when it kicked in! I always turned off the a/c when I had to overtake a road train.
I think the last time I used an a/c button was in my 1977 Audi - the compressor was so powerful you could feel the car decelerate when it kicked in! I always turned off the a/c when I had to overtake a road train.
05-23-13, 06:52 AM
#32
Lexus Champion
Thread Starter
Well, I use it all the time. So does my wife. So do a few other members. It is a hassle to go through menus when a simple button would have sufficed.
I don't want to completely turn off ventilation each time I open windows. Nor do I want to waste energy on running AC unnecessarily. Nor do I want an AC compressor whine when the hybrid would be in complete silence otherwise.
Bottom line, I use that button all the time. I wish the AC mode was visible and I wish the button was there.
Three are certain decisions I delegate for my vehicle to make, but this is not one of them. It is not tailored to my needs.
I don't want to completely turn off ventilation each time I open windows. Nor do I want to waste energy on running AC unnecessarily. Nor do I want an AC compressor whine when the hybrid would be in complete silence otherwise.
Bottom line, I use that button all the time. I wish the AC mode was visible and I wish the button was there.
Three are certain decisions I delegate for my vehicle to make, but this is not one of them. It is not tailored to my needs.
05-23-13, 08:12 AM
#33
Would anyone turn on the heat and AC in their house at the same time?
However, in some commercial, retail, and industrial buildings using outdoor air to meet ventilation and indoor air quality levels, A/C is used to dehumidify the air. Running it continuously results in discharge air temperatures that are uncomfortable and actually may cool building materials, i.e. masonry, to the point of sweating which may lead to mold formation. Heat is used to bring the dehumidified and cooled air back up to an acceptable level of comfort.
Although I'm not stating this as a fact, the Lexus may be doing humidification 1) because the ventilation switch is set to outdoor air, 2) the windows are open. Again, I have no basis in fact for this comment. Just a guess. Buildings, obviously, are not cars and are governed by standards and regulations perhaps not found in cars. I would think, guessing again, there are indoor air quality standards automobile manufacturers strive to maintain within the cabin. Using outdoor air, heating, cooling and dehumidification maybe part of their attempt to comply with those standards.
I can fully understand the desire to consume less fuel, not listen to an incessant whining and having a single button rather than one-button push and two mouse clicks to turn off the A/C enable switch (at least with a navigation display).
The one thing I might suggest, is compare the sound of your car to another of similar make, model and model year and make sure you do not have a faulty compressor or an incorrect refrigerant charge.
05-23-13, 08:29 AM
#34
Lexus Champion
Thread Starter
David, the compressor whine is normal. Our Prius did the exact same thing. I first noticed it when I was showing off the hybrid to my coworkers in the parking lot and was bragging how silent it is, except it wasn't completely silent. It took my by a surprise at first. It was later on that day that I realized the AC was ON at the time. Prius did have the AC button. It even has recirculation button on the steering wheel.
Honestly, I think the reason for removing this button is because a typical driver does not [want to] use it. Back when IS300 came out in 2000, it got criticized for not turning on the AC automatically. So, the next year revision had the AC turn on each time the climate control was put in auto. In order to turn the fan on from the off position, the dial goes past the AUTO mode, which triggers the the AC to come on. It is silly, but that's what the auto press (consumers?) wanted.
I think if the AC was used to control the humidity or other air qualities, it would also have to take into consideration if the windows or moonroof are open and by how much. It does not appear to be smart enough to make this determination.
Honestly, I think the reason for removing this button is because a typical driver does not [want to] use it. Back when IS300 came out in 2000, it got criticized for not turning on the AC automatically. So, the next year revision had the AC turn on each time the climate control was put in auto. In order to turn the fan on from the off position, the dial goes past the AUTO mode, which triggers the the AC to come on. It is silly, but that's what the auto press (consumers?) wanted.
I think if the AC was used to control the humidity or other air qualities, it would also have to take into consideration if the windows or moonroof are open and by how much. It does not appear to be smart enough to make this determination.
05-23-13, 11:57 AM
#35
What we have is pretty much the same through the Lexus lineup (with NAV). I don't see it changing, but you can adapt to it (mine is 4 years old now and I have). You have to or trade for something else. Personally I think it's pretty good. It's summer now in most areas. If you don't want your compressor running, just turn the fan off and open the window/sun roof. These cars are so well designed that we're nit picking just trying to find flaws IMHO.
Last edited by Cruiter; 05-31-13 at 03:26 AM.
05-23-13, 12:30 PM
#36
Lexus Champion
Thread Starter
Jim, while to most it's not a big deal, to me it is a big design flaw. The adaptation process here is to get used to the joystick and menu-clicking. 
I was really hoping for a secret button combination to be used as a shortcut.
I was really hoping for a secret button combination to be used as a shortcut.
05-23-13, 01:08 PM
#37
vlad_a,
I went into a nice quiet shop, with the ICE in full stop, although warmed up, and put my climate control in full cool. I grabbed an infrared thermometer to take some readings. The temp in the shop was about 70 degrees, the ducts in the car were discharging 42-45 degrees. With the hood open and NONE of the plastic covers removed there are two fans running at the radiators, One fan I believe is for both for the refrigeration condenser coil and partial engine radiator. The discharge temp out of the fan was about 95 degrees. So I'm fairly sure the compressor should have been running, although I don't know at what speed. Not likely full bore with an entering temperature of only 70 degrees at the evaporator coil. At least on my 2012 450h, I could not hear the compressor only those fans and also the fan for the cabin interior. No whining, unlike what you describe on your RX and Prius.
Turning off the A/C enable button does turn off the fans in the engine compartment and I would believe the compressor too with a slight time lag to perhaps pump down the compressor(?).
Thanks for this discussion, very interesting and made me investigate my own car.
I went into a nice quiet shop, with the ICE in full stop, although warmed up, and put my climate control in full cool. I grabbed an infrared thermometer to take some readings. The temp in the shop was about 70 degrees, the ducts in the car were discharging 42-45 degrees. With the hood open and NONE of the plastic covers removed there are two fans running at the radiators, One fan I believe is for both for the refrigeration condenser coil and partial engine radiator. The discharge temp out of the fan was about 95 degrees. So I'm fairly sure the compressor should have been running, although I don't know at what speed. Not likely full bore with an entering temperature of only 70 degrees at the evaporator coil. At least on my 2012 450h, I could not hear the compressor only those fans and also the fan for the cabin interior. No whining, unlike what you describe on your RX and Prius.
Turning off the A/C enable button does turn off the fans in the engine compartment and I would believe the compressor too with a slight time lag to perhaps pump down the compressor(?).
Thanks for this discussion, very interesting and made me investigate my own car.
05-23-13, 01:40 PM
#39
Lexus Champion
Thread Starter
vlad_a,
I went into a nice quiet shop, with the ICE in full stop, although warmed up, and put my climate control in full cool. I grabbed an infrared thermometer to take some readings. The temp in the shop was about 70 degrees, the ducts in the car were discharging 42-45 degrees. With the hood open and NONE of the plastic covers removed there are two fans running at the radiators, One fan I believe is for both for the refrigeration condenser coil and partial engine radiator. The discharge temp out of the fan was about 95 degrees. So I'm fairly sure the compressor should have been running, although I don't know at what speed. Not likely full bore with an entering temperature of only 70 degrees at the evaporator coil. At least on my 2012 450h, I could not hear the compressor only those fans and also the fan for the cabin interior. No whining, unlike what you describe on your RX and Prius.
Turning off the A/C enable button does turn off the fans in the engine compartment and I would believe the compressor too with a slight time lag to perhaps pump down the compressor(?).
Thanks for this discussion, very interesting and made me investigate my own car.
I went into a nice quiet shop, with the ICE in full stop, although warmed up, and put my climate control in full cool. I grabbed an infrared thermometer to take some readings. The temp in the shop was about 70 degrees, the ducts in the car were discharging 42-45 degrees. With the hood open and NONE of the plastic covers removed there are two fans running at the radiators, One fan I believe is for both for the refrigeration condenser coil and partial engine radiator. The discharge temp out of the fan was about 95 degrees. So I'm fairly sure the compressor should have been running, although I don't know at what speed. Not likely full bore with an entering temperature of only 70 degrees at the evaporator coil. At least on my 2012 450h, I could not hear the compressor only those fans and also the fan for the cabin interior. No whining, unlike what you describe on your RX and Prius.
Turning off the A/C enable button does turn off the fans in the engine compartment and I would believe the compressor too with a slight time lag to perhaps pump down the compressor(?).
Thanks for this discussion, very interesting and made me investigate my own car.
Excellent followup! Thanks for checking. Always good to get more intel on how the system works. It must be the fans in the engine compartment I'm hearing that spin-up when the AC is ON.
05-23-13, 01:41 PM
#40
Lexus Champion
Thread Starter
05-23-13, 02:57 PM
#41
This is the most frustrating thing about our new RX350. No push button manual A/C off button. The irony is that if you don't have NAV, then there's a button. With NAV though you have to go through their menu system. It's slow and tedious, they really need a faster way to turn it off.
05-27-13, 07:55 PM
#43
I'm a little surprised that no one has mentioned the other reason to shut off the compressor.
One of the persistent problems with automobile A/C systems has always been that bad mildewy smell that occurs when you first start it up following a heavy use day. It's talked about on most auto message boards after almost every summer HVAC discussion.
From what I understand, it's caused by moisture building up on the coils of the evaporator core. If you normally just run the A/C right up until you shut the engine off, that moisture stays on the coils with SOME of it draining off onto the floor or street. However, depending on the design of the system, enough can remain for it to develop a bad smell which can blow into the cabin the next day.
The easiest "fix" for this has been to shut off the compressor a short time/distance before parking the vehicle. Doing this will eliminate much more of that moisture. I usually do this within a half mile of my destination and have been doing it for more years than I can remember...and I go back to the "pre-A/C" car days.
THIS is another reason Toyota should not have eliminated a "hard button" for the compressor or at the least not buried it as deep in the menu. Our other vehicles are an '09 Camry Hybrid and '09 Corvette, both with OEM NAV and each has a separate "hard button" for the compressor.
I understand this topic has been pretty much been COMPRESSED to death on this topic. I'm just adding another valid reason for vlad_a's original post.
One of the persistent problems with automobile A/C systems has always been that bad mildewy smell that occurs when you first start it up following a heavy use day. It's talked about on most auto message boards after almost every summer HVAC discussion.
From what I understand, it's caused by moisture building up on the coils of the evaporator core. If you normally just run the A/C right up until you shut the engine off, that moisture stays on the coils with SOME of it draining off onto the floor or street. However, depending on the design of the system, enough can remain for it to develop a bad smell which can blow into the cabin the next day.
The easiest "fix" for this has been to shut off the compressor a short time/distance before parking the vehicle. Doing this will eliminate much more of that moisture. I usually do this within a half mile of my destination and have been doing it for more years than I can remember...and I go back to the "pre-A/C" car days.
THIS is another reason Toyota should not have eliminated a "hard button" for the compressor or at the least not buried it as deep in the menu. Our other vehicles are an '09 Camry Hybrid and '09 Corvette, both with OEM NAV and each has a separate "hard button" for the compressor.
I understand this topic has been pretty much been COMPRESSED to death on this topic. I'm just adding another valid reason for vlad_a's original post.
05-27-13, 08:02 PM
#44
I've had more cars in my life than I can count and definitely understand what you're saying. However my 2010 (h) has nearly 50k on him now and probably the 1st car that hasn't had that issue. I'm not sure why but grateful. I do notice that the system on full automatic spends quite a bit of time on recirculation. Maybe that's the reason ??? Whatever Toyota/Lexus IMHO has it figured out. After parking in the garage, I do see a 'summer' puddle. I'm used to the interior smells now but recently a rider said it still looks and smell new. WOW
I'm a little surprised that no one has mentioned the other reason to shut off the compressor.
One of the persistent problems with automobile A/C systems has always been that bad mildewy smell that occurs when you first start it up following a heavy use day. It's talked about on most auto message boards after almost every summer HVAC discussion.
From what I understand, it's caused by moisture building up on the coils of the evaporator core. If you normally just run the A/C right up until you shut the engine off, that moisture stays on the coils with SOME of it draining off onto the floor or street. However, depending on the design of the system, enough can remain for it to develop a bad smell which can blow into the cabin the next day.
The easiest "fix" for this has been to shut off the compressor a short time/distance before parking the vehicle. Doing this will eliminate much more of that moisture. I usually do this within a half mile of my destination and have been doing it for more years than I can remember...and I go back to the "pre-A/C" car days.
THIS is another reason Toyota should not have eliminated a "hard button" for the compressor or at the least not buried it as deep in the menu. Our other vehicles are an '09 Camry Hybrid and '09 Corvette, both with OEM NAV and each has a separate "hard button" for the compressor.
I understand this topic has been pretty much been COMPRESSED to death on this topic. I'm just adding another valid reason for vlad_a's original post.
One of the persistent problems with automobile A/C systems has always been that bad mildewy smell that occurs when you first start it up following a heavy use day. It's talked about on most auto message boards after almost every summer HVAC discussion.
From what I understand, it's caused by moisture building up on the coils of the evaporator core. If you normally just run the A/C right up until you shut the engine off, that moisture stays on the coils with SOME of it draining off onto the floor or street. However, depending on the design of the system, enough can remain for it to develop a bad smell which can blow into the cabin the next day.
The easiest "fix" for this has been to shut off the compressor a short time/distance before parking the vehicle. Doing this will eliminate much more of that moisture. I usually do this within a half mile of my destination and have been doing it for more years than I can remember...and I go back to the "pre-A/C" car days.
THIS is another reason Toyota should not have eliminated a "hard button" for the compressor or at the least not buried it as deep in the menu. Our other vehicles are an '09 Camry Hybrid and '09 Corvette, both with OEM NAV and each has a separate "hard button" for the compressor.
I understand this topic has been pretty much been COMPRESSED to death on this topic. I'm just adding another valid reason for vlad_a's original post.
05-28-13, 02:24 AM
#45
Driver
I don't know about that mildew smell you guys are talking about - I've never experienced it, and that includes several years living in the tropics.
When I was trading in my 2006 RX350 earlier this year I had a colleague ask "why are you selling it - it's brand new isn't it?"
When I was trading in my 2006 RX350 earlier this year I had a colleague ask "why are you selling it - it's brand new isn't it?"