"Auto" Climate Control

whaaaaa

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double post, whoops
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Jon Snow

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Or will we be forced to listen carefully for whether the compressor is clicking on and off?
According to Honda, the A/C in the new Civic uses some kind of new variable compressor technology that instead of just kicking on and off can scale anywhere in-between. Thus, it may be "on" most of the time, but could be using significantly less power. And it probably means you will not hear the compressor cycling on and off, and could be the explanation for why Honda no longer shows A/C status as a simple on/off light.
 

whaaaaa

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According to Honda, the A/C in the new Civic uses some kind of new variable compressor technology that instead of just kicking on and off can scale anywhere in-between. Thus, it may be "on" most of the time, but could be using significantly less power. And it probably means you will not hear the compressor cycling on and off, and could be the explanation for why Honda no longer shows A/C status as a simple on/off light.

Very interesting!!! Do you have a link I can read for more info by any chance?

I was going by ear just yesterday and manually flipping the a/c between auto and off, and it does seem that while climate is on fully auto mode the a/c is engaged most if not all of the time.
 

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Ok, so after some further testing with a better thermometer, I've found that the car's climate control is indeed off by around 7-8 degrees F, as was my initial guess. I'm not 100% confident in the accuracy of this thermometer, but it's clearly way more trustworthy than the unit I used for my previous test. I did hold it up to my home thermostat which was displaying a room temp of 69, and the instant read thermometer read 69.7, so close enough for this case. For all tests I positioned the thermometer carefully in the center console, making sure that it was not getting a direct air current from any vent, and making sure that the sensor was not coming into contact with anything except air. Just for extra confirmation, I also held the thermometer near the car's sensor under the steering wheel and saw identical readings. The thermometer is sensitive to 0.1 degrees, but due to practicality and reality I am just rounding to the nearest degree. In all cases, once reaching what the car believed to be its set point, the thermometer showed minor fluctuations of about 0.2 degrees in either direction.

First test, 40 degrees outside temp, drove about 20min with the climate control set at 70, beginning with a cold car. Reached destination, checked thermometer, and it showed 78 and holding pretty steady. I then sat in the parking lot for about 20min (wasting gas) to play with some finer adjustments. First I set the temp down to 65, while I watched the thermometer creep downward. To the car's credit, the temperature in the cabin began falling near instantly as soon as I made the adjustment. I kept watching the thermometer until it eventually leveled off at 73 after a couple minutes. Next I set the climate down just two degrees more at 63, and the thermometer leveled off at 71. Went down to 59, and the thermo leveled at a steady 67. Went back up to 68, and the thermometer predictably read as 76.

From this test it's clear that the sensor calibration was off by exactly 8 degrees, with maybe a margin of error of 1 or 2 degrees due to the nature of the thermometer I used. On the positive side, the climate control is extremely responsive and precise. With each adjustment the temperature rose and fell very rapidly, and once reaching its set point it held very steady with extremely minimal fluctuations. The only real issue here is that you have to subtract 8 degrees from the temperature you really want.

Next test, 35 degrees outside temp, cold car, started off this drive with the climate control set at 62 and went about 30min. Upon arrival checked the thermometer and it showed 69. Inched the control up to 64, and within 2 or 3 minutes the thermometer stabilized at 71. So this time the offset appeared to be 7 degrees, but I am willing to attribute that minor discrepancy from the first test to the thermometer more than the car, as 1 degree is well within a reasonable margin of error.

Final test (for now), 20 minute drive, 40 degrees outside, cold car, climate set to 65. Got home and thermometer read 72.

So again, the car's climate control is actually really nice and really precise, it's just offset by a whopping 7-8 degrees. Knowing this, it should be easy to compensate mentally and just keep the climate set to 60-65 for comfort, depending on the season and outerwear. On the other hand, that's a hell of an offset! Plus, the climate control's range only goes down to 58 before hitting max "Lo" which leaves very little room at the bottom if anyone should want it cooler than usual. At a setting of 58, I can expect the actual temperature in the car to maintain 65-66. I don't know why anyone would want to cooler than that really, but if they did, they should have the ability to go colder all the way down to 58 as it's supposed to be. I fully intend to badger my dealership service dept about this issue and bring all the evidence I can, and I encourage everyone else to do the same. The first time I mentioned it I was told that there was no way to calibrate the cabin sensor, which is kind of ridiculous if you think about it. Even with the outside thermometer, there's a user controllable adjustment where you can move it +/- a few degrees if you feel it's not accurate. If there's really no way to calibrate the climate sensor, I would be shocked, and then I would demand they get Honda to figure something out.

Granted all of my testing was done on cold days using the heat, and I remain curious how well it performs with cooling the cabin on hot days. I have a 60 degree and sunny day coming up next week, so I may park in the sun with the moonroof unshielded for a while to try to get the cabin temp up to 80-90 if I can, and then see what happens.
Excellent set of experiments. They match my results almost exactly. I'm not going to make a special trip to the dealer for this, but I will mention it the next time I take it in (for warranty item or maintenance). I too am looking for warmer days when I can see how it does handling the heat. Thanks again!
 

Jon Snow

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Very interesting!!! Do you have a link I can read for more info by any chance?
http://news.honda.com/newsandviews/article.aspx?id=8710-en

About 2/3 of the way down the page.

Climate Control Systems
For the first time ever, all Civic models have a standard automatic climate control system. The new system offers a 10-percent improvement in warm-up time compared to the previous system and now features a refrigerant with a much lower GWP (Global Warming Potential). To help conserve energy, the system employs a new Variable Displacement Compressor (VDC). Unlike a conventional compressor which can only operate at 100-percent and must be switched on and off frequently to conserve fuel when the cooling load is relatively low, the VDC can vary its output based on the cooling needs, resulting in greater efficiency, reduced drag on the engine and smoother climate-control performance.
 


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Excellent set of experiments. They match my results almost exactly. I'm not going to make a special trip to the dealer for this, but I will mention it the next time I take it in (for warranty item or maintenance). I too am looking for warmer days when I can see how it does handling the heat. Thanks again!
It was warm today so I experimented with the AC for the first time. Does anyone know what the temperature of the air should be leaving the vents for a car with a correctly operating AC (adjusting for external temperature and relative humidity)? My vents were pushing air at about 48F (measures with digital, instant-read thermometer). I had ECO off.
 

whaaaaa

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It was warm today so I experimented with the AC for the first time. Does anyone know what the temperature of the air should be leaving the vents for a car with a correctly operating AC (adjusting for external temperature and relative humidity)? My vents were pushing air at about 48F (measures with digital, instant-read thermometer). I had ECO off.
I'm not an expert, but that sounds about right, depending... Output temp doesn't actually tell you much without knowing the intake temp. Some cursory googling shows that a functioning a/c should cool the intake air by around 20 degrees, provided you're measuring the temperature at the correct point and not actually getting a reading of a/c air mixed with cabin air.

That said, the Civic a/c seems like a pretty smart/complex unit what with the variable compressor I just learned about, so I wouldn't be surprised if it scales back its cooling power when the outside temp is not super hot in order to conserve gas.

I think the more relevant question is, did the a/c cool the car to your chosen set point successfully? (factoring in the 6-8 degree offset, of course)
 
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whaaaaa

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So after a few more days of testing, including a couple warm days, the offset seems to be consistent at 6-7 degrees. I've been keeping my climate set to 62-64, which keeps the actual cabin temperature at 68-70. I got to test it out on a hot sunny day, and the a/c with the variable compressor worked beautifully, accounting for the exact same offset as when heating. It was 70 degrees outside, and 100 degrees in the cabin when I got in. Set the climate to 64, and it cooled down to exactly 70 degrees and maintained it right there.

If I had only been driving this car in a hot climate and had no winter heating situations to compare it to, I can understand why it might seem to some people that the a/c is not blowing cold enough and might be broken, when in fact it's just that the cabin sensor is off by a good bit and the a/c actually works just fine.

I'm actually surprised this issue isn't getting more attention, as climate control is something that everyone uses at all times pretty much, and a calibration difference of 6 degrees from expectations is very noticeable. I wish some people would chime in who are not actually experiencing this same issue, to shed some light on whether this is widespread and uniform across all 2016 civics, or just a small subset.
 

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So after a few more days of testing, including a couple warm days, the offset seems to be consistent at 6-7 degrees. I've been keeping my climate set to 62-64, which keeps the actual cabin temperature at 68-70. I got to test it out on a hot sunny day, and the a/c with the variable compressor worked beautifully, accounting for the exact same offset as when heating. It was 70 degrees outside, and 100 degrees in the cabin when I got in. Set the climate to 64, and it cooled down to exactly 70 degrees and maintained it right there.

If I had only been driving this car in a hot climate and had no winter heating situations to compare it to, I can understand why it might seem to some people that the a/c is not blowing cold enough and might be broken, when in fact it's just that the cabin sensor is off by a good bit and the a/c actually works just fine.

I'm actually surprised this issue isn't getting more attention, as climate control is something that everyone uses at all times pretty much, and a calibration difference of 6 degrees from expectations is very noticeable. I wish some people would chime in who are not actually experiencing this same issue, to shed some light on whether this is widespread and uniform across all 2016 civics, or just a small subset.
I agree (same experience). By the way, when you have your system set on Auto, does the Climate Control display show whether the AC is actually on or not? I think the AC is on, but it is not indicated on the display unless I manually turn it on (which also turns Auto off).
 


whaaaaa

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I agree (same experience). By the way, when you have your system set on Auto, does the Climate Control display show whether the AC is actually on or not? I think the AC is on, but it is not indicated on the display unless I manually turn it on (which also turns Auto off).
Same here. It shows as being neither on nor off, however I can hear the compressor going. It's quiet, but noticeable when you manually force it off and then back on by hitting auto again. Kind of annoying as the 2013 civic did show whether the a/c was engaged or not while on auto, but maybe removing that visibility has something to do with the new variable compressor as it's now designed to be engaged most if not all of the time anyway. I do get the indicator light telling me whether the system is in recirculation or fresh air mode, however.
 

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Any fix from Honda on this problem? Does the 2017 Civic have the same problems with climate control.
I have 2016 EX Sense made in August and has the same problem as described by whaaaaa.
 

whaaaaa

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Any fix from Honda on this problem? Does the 2017 Civic have the same problems with climate control.
I have 2016 EX Sense made in August and has the same problem as described by whaaaaa.
Should have followed up on this long ago, but somehow, strangely, the Auto climate seems to have somewhat sorted itself out for me. All summer long I was able to set my car to a nice 68-70, and the cabin temperature seemed to hit that mark more or less accurately. Waiting for it to get cold out again so I can see if the heating system operates any differently than when the car was brand new.
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