Civic AC heading for lawsuit?

  1. Gruber

    Gruber Senior Member

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    Definitely don't set the fan speed to high to check the vent temperature.

    I don't think you can count on 40 F temperature drop by any properly working AC system, auto or home. This is certainly not typical and not as it should be. If you do see 40 F cooling, it might be in reference to the temperature outside, while you are recirculating, so it's not what you are supposed to be measuring. You should in this case measure the difference from the temperature inside the car. Or it is actually cooling too much and at risk of freezing over the evaporator, which should never happen. Generally, after it gets steady after some 15 minutes, the temperature difference between inlet and outlet should not be much more than 20 F and if it's 15 F it's still fine.

    While always cooling by up to 20 F, the ability of the system to maintain a comfortable temperature on very hot and humid days depends on the size of the system, which practically means more pounds of refrigerant. Outside temperature might be 130 F and the temperature inside the car set to recirculation could be a cool 65 F. That doesn't mean that the delta T is 65 F. In this case the temperature of the air out of the vents might be 45 F, only 20 F difference from the inlet air.

    AC systems tended to be bigger in older good cars and in luxury cars at any time, so they would provide adequate cooling even on extremely hot and humid days, but the temperature difference between inlet and outlet air in a properly working AC in steady state should still never significantly exceed 20 F.

    Some Honda civics in the XX century had about twice or more refrigerant than today. And in the early 90's it was still R12, which has more cooling capacity per pound than R134a. There are many ways of saving energy when less than maximum cooling is needed, but no breakthrough was invented since 40 years ago to make 15 ounces of refrigerant have the same cooling power as 30+ ounces.

    https://www.techchoiceparts.com/refrigerant-and-oil-capacities/honda
     
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  2. SCOPESYS

    SCOPESYS Senior Member

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    I have always consider 40F to be the top range of differential temperature, both in the House A/C, and in the cars.
    Both our House A/C, the 2018 Si, and the 1987 Maxima achieve close to this when they are working correctly.

    You go on to say that 20F is more typical .. are you sure you don't mean 20C ??

    I was testing my Maxima yesterday, it was 95F outside, and about 90% Humidity (Baltimore weather suck at this time of the year), and I was getting 60F out of the A/C vent on low fan speed. Thats a 35F differential , which is quite good for the 32 year old Maxima, which has not had its R134a refrigerant re-charged for the past 3 years.
    (It was even better than that some 20 years ago, when it was still R12, but those days are long gone )

    Later that day, we went for a 1 hour trip in the SI, and while I did not have the thermometer with me, the cold are coming out of the vents, felt even colder than the Maxima, so much so, that after a time, it was more comfortable to turn back the cooling - that cold air can actually become painful !!

    BTW: Looking at my SI's Condenser, the condenser look Pristine, no sign of any bending or distortion of fins, and certainly no stone damage (yet).

    I do plan to add a fine wire mesh to the air intake for the Condenser, because I am probably on borrowed time, and it may only take one rouge stone to cause a leak.

    However, my belief at the moment, is that most of these Civicx refrigerant leaks are cause by stress cracks developing in what is basically a very lightweight and delicate condenser, and associated pipes and joints.
     
  3. frontlinegeek

    frontlinegeek Senior Member

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    The overriding factor is heat energy saturation at the absolute level. Hot humid air is very difficult to push more heat into. Once, down in Orlando, when we rented a house for vacation, the instructions on what to set the house to for temp stated in no uncertain terms to not go below 76F or the system risked icing and that we would be on the hook for the service call.

    At my house, with a geothermal heat pump, I can set the temperature to 68 and leave it regardless. And we do get mid to high 90s with 75% or higher humidity where I live, in the summer. The ground is at such a massive temperature delta compared to what I am pushing down there, it is no issue for the GHP at all.

    Of course, no ground option is available to an automobile :)

    A 20 F delta would be reasonable for most air to air systems at the upper RH levels. Cooling the air from 90 to 70 with a greatly reduced cabin humidity level would feel fantastic. Even 95 down to 75 at say only 35% RH would be a treat. 20 C would be both crazy and uncomfortable. 32C is basically 90F. I would not want my car to be 12C/54F. 12C in the center console vents deep in with a long reach thermometer, sure. But certainly not the whole cabin temp.
     
  4. TheKevinlyFather

    TheKevinlyFather Senior Member

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    Central Ohio, but yes it has been quite humid lately. Yesterday wasn't bad, but was still hot. Could be weather related for sure.
     
  5. SCOPESYS

    SCOPESYS Senior Member

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    Congrats on the Geothermal system .. a great way to go both now and into the future.
    If you can power your Geothermal system with Solar, you can't get much better than that for low cost heating & cooling.

    Many people forget that it is AIR CONDITIONING, not just Air COOLING.
    Get rid of the Humidity, and that's the major part of the battle to FEEL cooler.

    DRY heat is a lot more tolerable than HUMID Heat !!
     
  6. BriteBlue

    BriteBlue Senior Member

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    Here's a chart from one of my other cars. It lists the Maximum Allowable vent outlet temperature & it's about 40 degrees cooler than the Ambient temperature in all cases.

    AC temps.jpg
     
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  7. SCOPESYS

    SCOPESYS Senior Member

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    Interesting it doe not mention Humidity, or whether this maximum Low Temperature is to be measured with the car stationary, or moving, or at what Fan speed , but it does correctly indicate what general cooling one should be looking for.

    In any case, for those with a defective Gen X A/C, even 10 degrees cooler than ambient might be welcome !!
     
  8. BriteBlue

    BriteBlue Senior Member

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    I only copied the temperature part of the chart but they do list all the high & low pressures for the respective temperatures. It also states "High humidity reduces the evaporator’s ability to cool the air. During periods of high heat and humidity, an air conditioning system will be less effective." They do mention connecting the manifold gauges & keeping the engine at 1,000 RPM.with the AC clutch engaged. IOW there is more info than just the small part I posted.

    The manual says "Air temperature in test room and in vehicle must be 21° C (70°F) minimum for this test".
    ² A/C ON
    ² Panel Recirculation
    ² Temperature to full cold
    ² High blower
     
  9. Gruber

    Gruber Senior Member

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    #114 Gruber, Jul 17, 2019
    Last edited: Jul 17, 2019
    Seriously? If you have the home A/C set to 76 F and this is the temperature in the house, you would expect the vents to blow 36 F air? This could happen if the system is oversized, air filters are clogged, or the fan is slow.It would be close to the coil evaporator freezing. Many businesses such as restaurants set their AC to 70 C or so. They would freeze their evaporators if they could achieve a 40 F difference.

    For home A/C the magic numbers repeated in dozens of different internet advice sites are 14 to 20 degrees Fahrenheit difference between the return (room) air and the vent air. Above or below this range indicates potential issues. Of course building A/C is designed to always recirculate air, so they are relatively smaller.

    https://www.lowes.com/cd_Test+Your+...bility_1351517191983_ng+Ability_1351517191983

    With cars everything depends on the fan speed and the air humidity. Indeed with the slowest fan speed (depending on how slow is slow) and a high capacity AC system the vent air temperature may go really low, almost to the actual evaporator temperature. But I don't see how the Honda A/C performance charts like above can be independent of the air humidity. I doubt you will reach these temperatures in a 10th gen Civic at muggy conditions.

    For example, to bring the outside air from 95 F, 85% RH to quite comfortable 75 F, 50% RH, over five times more energy is needed to condense the excess water then to cool the humid air. To cool one civicxload of air (about 4 kg of air fits inside) between these conditions, the heat of condensation of about 90 g (3+ oz) of water must be removed. (Where I am the air humidity is "only" 79% now but it was 87% earlier today).
     
  10. Gruber

    Gruber Senior Member

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    Ok, so this is with recirculation and high fan. So the numbers in the table probably reflect the lowest temperature that the AC will get to after some time (when taking in already cooled inside air). Not what it can do instantaneously with the ambient air.
     
  11. BriteBlue

    BriteBlue Senior Member

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    The table states Maximum Allowable temperature. That would mean the temperature should actually be cooler.
     
  12. BriteBlue

    BriteBlue Senior Member

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    I just got this email from the company that services our house AC.

    "Air Conditioners are designed to keep your home up to 20 degrees cooler than the outside temperature and are sized based on regional summer temperatures."

    "Your unit was designed and sized for the average regional temperatures we experience 98% of the time. Turning down your thermostat will not make it blow colder air. Set the thermostat to the temperature you want to achieve and leave it set there."

    "When outside temps reach near or over 90 degrees, it is normal for the temps to go up in your home during the hottest part of the day."

    I might add - when the AC tech was at our house a couple years ago he said the air coming out of the vents should be 55-60 degrees. At the time our inside temp was 75 degrees and a first floor vent was blowing out 56 degrees and a second floor vent was blowing out 59 degrees. I should have taken notes on the outside temp & humidity but didn’t think of that at the time.
     
  13. frontlinegeek

    frontlinegeek Senior Member

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    Thanks! We built with that as part of the build and the ROI was less than 5 years. Longer term, we are planning for solar with grid tie and grid down backup but the panels will be the last part as I want to wait for higher efficiency panels than what is available now. Specifically waiting for the next leap of 10% more absolute efficiency, so from the 20-22 now to in excess of 30.

    For sure! I got Vegas off my bucket list this spring and got to experience desert heat for the first time and can totally relate.
     
  14. Gruber

    Gruber Senior Member

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    No kidding. You can spend quite some time quite comfortably in dry air at the temperature exceeding water boiling point (over 100 C or 212 F), but if you add water, you will get out pretty quickly.
     
  15. Sitio23

    Sitio23 Senior Member

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    #120 Sitio23, Jul 18, 2019
    Last edited: Jul 18, 2019
    So I just got my quote to replace the AC in my car. Picture attached. Seems a bit steep if you ask me.

    IMG-1410.JPG
     
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