Questions for Hummer Techs out there..

[h2sin]

Q#1: How much adjustment can be done to the rear bumper? Yesterday I noticed the right side of the rear bumper(where it meets the rear fender flare)is about 1/4 inch off compare to the left side. Dealer said the holes for the bumper support brace has to be modified http://www.elcova.com/infopop/emoticons/icon_eek.gif Any other solution to this problem?

Q#2: With AC setting maxed(recirculation on), what should the ac vent temp be at? Ambient temp is about 85ish

[h2sin]

Q#1: How much adjustment can be done to the rear bumper? Yesterday I noticed the right side of the rear bumper(where it meets the rear fender flare)is about 1/4 inch off compare to the left side. Dealer said the holes for the bumper support brace has to be modified http://www.elcova.com/infopop/emoticons/icon_eek.gif Any other solution to this problem?

Q#2: With AC setting maxed(recirculation on), what should the ac vent temp be at? Ambient temp is about 85ish

[intimidator]

question#1 is for a body man. question#2 all depends on the humidity.at 85f with 70% humidity at idle the outlet temp should be between 55 to 60f

[Hummertech]

Q#1. a 1/4 " difference is not very much. If your truck is under warranty, you can tell the dealer, ****in fix it.
If you would rather do it yourself, this is how I would do it if it was my truck. Get a floor jack, and a block of wood. Jack up the side thats a little low. Jack it up higher than it needs to be because you want to put a little bend in it. It will bend back a lot when you lower the jack. It may sound surprising, but you would be surprised how many things are actually fixed this way.

[LasVegas]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by intimidator:
question#1 is for a body man. question#2 all depends on the humidity.at 85f with 70% humidity at idle the outlet temp should be between 55 to 60f </div></BLOCKQUOTE>Intimidator...just exactly what does humidity have to do with it?

[LasVegas]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Posted by H2sin Q#2: With AC setting maxed(recirculation on), what should the ac vent temp be at? Ambient temp is about 85ish </div></BLOCKQUOTE>Humidity has nothing to do with it. In a fixed orifice R-134A system (h2s) you can expect a temperature split of between 17-20 degrees across the evaporator coil. That means if 85 degree air is entering somewhere between 65-68 degree air should be discharging. This of course will come down as the cabin temperature cools down. So the discharge temperature will vary depending on load. Once the cabin is at temperature, say 72 degrees you should be getting a discharge temperature of around 55 degrees if you're recirculating. If it's not on recirculation and bringing in some outside air it will be higher.

[Beastmaster]

Humidity affects how efficient the coils transfer heat.

The more humidity, the harder the A/C has to work.

IIRC, the general rule of thumb is that A/C units in vehicles will work 30 degrees lower than the ambient temp.

-Steve

[LasVegas]

Sorry guys...wrong. Humidity has nothing to do with it.

[PARAGON]

Sorry Jonahs, you are quite wrong here. Humidity effects the ability coils to transfer heat because higher humidity means that the condensing water vapor will collect on the coils and act like an insulator. It will effectively keep the coil from further reducing the temperature. It all has to do with relative humidity.

Air conditioning systems in your part of the world work much better than here in our part. As far as the recirculation is concerned, the vehicle is not a sealed compartment so relative humidity is not going to go down that significantly even during long trips on high with recirculate on.

Now when a tech is testing the temp at the outlet, relative humidity is even more important because the outside air IS what is going through no matter what.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Humidity is an element of A/C service that often gets overlooked. First, let's look at the word "humidity". Humidity can be described in two ways: humidity and relative humidity. Humidity is water vapor held in the air. Relative humidity, as defined by Webster, is "the ratio of the amount of water vapor actually present in the air to the greatest amount possible at the same temperature." As air temperature rises, its ability to hold moisture increases, which means hotter temperatures can retain more moisture.

Second, let's look at how humidity effects our comfort zone. The average person feels comfortable within a relative humidity of 40% to 50%. When relative humidity is higher than 50%, people feel hotter and muggier. The term "Heat Index" refers to how hot it "feels" when temperature and humidity are taken into consideration. An 80ºF day with 90% humidity will feel hotter than a 90ºF with 20% humidity.

As the A/C system cools, the evaporator core absorbs heat from the air inside the vehicle and transfers that heat to the air outside through the condenser. As the air cools, excess moisture condenses into water. The water coats the evaporator core, which affects its ability to absorb heat from the air. In a sense, the water acts like an insulator. However, as the humidity level drops inside the car, the air temperature will feel colder.

How will this affect temperature and pressure readings? As relative humidity increases, the difference between the duct and ambient temperatures will decrease. For example, an ambient temperature of 85ºF with low humidity could result in a duct temperature of 40ºF, but with high humidity may only produce a duct temperature of 55ºF. Also, high and low pressure readings will rise slightly as relative humidity increases. The rise in pressure is due to the fact that water contains more heat than air.
</div></BLOCKQUOTE>

[h2sin]

I took it to the dealer and asked them not to modify the support brace in any way, we'll see how close they can get it to match the other side just by shifting the bumper.

I was expecting lowered from the AC vent so 55-60 sounds about right. thanks for all the info http://www.elcova.com/infopop/emoticons/icon_smile.gif

[LasVegas]

Paragon...you are scientifically correct as are the others. The properties of refrigerant are constant...at a given pressure it has a given temperature, regardless of humidity. Humidity over the evaporator coil is turned to condensate water slightly above the temperature of the coil itself. Thus the discharge range of 17-20 air on/off the coil. So I will concede a slight effect but very little. The example in your quote is highly exaggerated. A portion of all air conditioning capacity is dedicated to humidity at about 50% relative humidity standard. The higher the humidity (latent load)the lower the sensible temperature difference across the coil. So I will correct myself and say it does have some effect but in the practical world not much. In a proper operating 134a system you'll still get 17-20 split across the coils across the humidity range. At higher humidity how the discharge temperature feels to the person is a totally different story. Humidity is so Insignificant my technicians don't even consider it when making diagnosis.

[PARAGON]

That's because you guys have no humidity. We train for our humidity whilst breathing in the womb. http://www.elcova.com/infopop/emoticons/icon_wink.gif

[LasVegas]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PARAGON:
That's because you guys have no humidity. We train for our humidity whilst breathing in the womb. http://www.elcova.com/infopop/emoticons/icon_wink.gif </div></BLOCKQUOTE>Again I'll have to concede you are really correct there. Typical 10-15% except for a couple times a year. I guess I was answering his question from the "practical" standpoint vs scientific standpoint. You are all correct.

[ROX]

What's the average temperature of the sun during a one year cycle? http://www.elcova.com/infopop/emoticons/icon_rolleyes.gif

[LasVegas]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by H2 Rocks:
What's the average temperature of the sun during a one year cycle? http://www.elcova.com/infopop/emoticons/icon_rolleyes.gif </div></BLOCKQUOTE>Hot

[PARAGON]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by H2 Rocks:
What's the average temperature of the sun during a one year cycle? http://www.elcova.com/infopop/emoticons/icon_rolleyes.gif </div></BLOCKQUOTE>That's kind of hard to answer. Where are you talking about? At the sun's core, at the surface, etc.

http://www.elcova.com/infopop/emoticons/icon_wink.gif http://www.elcova.com/infopop/emoticons/icon_biggrin.gif

[ROX]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LasVegas:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by H2 Rocks:
What's the average temperature of the sun during a one year cycle? http://www.elcova.com/infopop/emoticons/icon_rolleyes.gif </div></BLOCKQUOTE>Hot </div></BLOCKQUOTE>
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Originally posted by PARAGON:
That's kind of hard to answer. Where are you talking about? At the sun's core, at the surface, etc. </div></BLOCKQUOTE>

Hard to answer? YOU? Jonahs got it right! A+ http://www.elcova.com/infopop/emoticons/icon_biggrin.gif
What's the average temperature of the sun's corona during a one year cycle?
Answers must be typed in red, and between 5 and 2 billion words. http://www.elcova.com/infopop/emoticons/icon_wink.gif http://www.elcova.com/infopop/emoticons/icon_biggrin.gif

[PARAGON]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by H2 Rocks:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Originally posted by PARAGON:
That's kind of hard to answer. Where are you talking about? At the sun's core, at the surface, etc. </div></BLOCKQUOTE>

Hard to answer? YOU? Jonahs got it right! A+ http://www.elcova.com/infopop/emoticons/icon_biggrin.gif
What's the average temperature of the sun's corona during a one year cycle?
Answers must be typed in red, and between 5 and 2 billion words. http://www.elcova.com/infopop/emoticons/icon_wink.gif http://www.elcova.com/infopop/emoticons/icon_biggrin.gif </div></BLOCKQUOTE>Ok, I don't adhere to formatting requests. First, we have to determine what you mean by a one year cycle. Since, terrestially-speaking, a year is generally considered one revolution of the earth around the sun, it could also be mis-construed as one revolution of the sun itself, which is approximately 1 month.

Considering that you must be speaking of the Gregorian/Julian calendar we'll use the typical 365 day year that is commonly used now. On average the coronal portion of the sun, which extends millions of miles around the sun's surface, is at about 2,000,000 degrees Kelvin. This is with exception to coronal holes where the temperature is significantly lower. This average temperate is substantially higher that the average surface temperature of about 6,000 Celsius. Does this satisfy your curiousity?

Oh, by the way, http://www.elcova.com/infopop/emoticons/icon_wink.gif

[tower]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LasVegas:
Hot </div></BLOCKQUOTE>

Gosh, Jonahs. I hate for you to get corrected twice in one thread. But the actual correct response is "Damned Hot." Additionally, "Got Damned Hot!" is considered acceptable. http://www.elcova.com/infopop/emoticons/icon_biggrin.gif

[ROX]

Now I know about:
how humidity affects my A/C;
and how hot it must get in Mississippi! http://www.elcova.com/infopop/emoticons/icon_wink.gif http://www.elcova.com/infopop/emoticons/icon_biggrin.gif

[LasVegas]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Posted by Tower...Gosh, Jonahs. I hate for you to get corrected twice in one thread. </div></BLOCKQUOTE>Whoa Tower. Let's not get hasty with the corrected word. I answered a question by H2Sin on discharge temperature. He didn't ask for the principles of air conditioning or how does humidity affect my system. Commercial buildings are designed for peak loads and extreme latent heat and then the DX (direct expansion) controlled by unloaders, bypass or other controls. Well designed vehicle systems are likewise designed for peak loads because of their extreme varying conditions, radiant heat, etc. and inexpensively controlled by cycling the compressor. They can do that because it's externally driven by the engine. Out of curiousity I connected my thermistor to the center duct for a day. During balanced operation it maintained a solid 20 degree split across the coil and at heavy load after sitting in the sun all day got as high as a 31 degree split for a short while. I then drove it through the car wash and had it call for maximum cooling. I'm sure you can guess the humidity and the split didn't change over 1 degree. The discharge temp actually went down but that's because of the lower ambient inside the car wash. Humidity DOES affect a/c but that wasn't the question and if the vehicle system is designed well you shouldn't notice a large change in discharge temperature. But then again, what do I know. I'm sure Google takes precedence over the 52,000 a/c service calls we've run the last 4 years. http://www.elcova.com/infopop/emoticons/icon_biggrin.gif

[PARAGON]

<TABLE width="100%" border=1><A href="#tab2-817504">
<H4><FONT color=#254164>A/C Performance Table</FONT></H4></A>
<TBODY>
<TR>
<TH vAlign=bottom align=middle rowSpan=2>
<Font size=1>

Ambient Air Temperature</P></TH>
<TH vAlign=bottom align=middle rowSpan=2>
<Font size=1>

Relative Humidity</P></TH>
<TH vAlign=bottom align=middle colSpan=2>
<Font size=1>

Service Port Pressure</P></TH>
<TH vAlign=bottom align=middle rowSpan=2>
<Font size=1>

Maximum Left Center Discharge Air Temperature</P></TH></TR>
<TR>
<TH vAlign=bottom align=middle>
<Font size=1>

Low Side</P></TH>
<TH vAlign=bottom align=middle>
<Font size=1>

High Side</P></TH></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

13-16°C (55-65°F)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

0-100%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

200-283kPa (29-41psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

945-1234kPa (137-179psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

11°C (52°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle rowSpan=2>
<Font size=1>

19-24°C (66-75°F)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

Below 40%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

228-310kPa (33-45psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1082-1413kPa (157-205psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

14°C (57°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

Above 40%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

248-338kPa (36-49psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1131-1469kPa (164-213psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

15°C (59°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle rowSpan=3>
<Font size=1>

25-29°C (76-85°F)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

Below 35%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

276-379kPa (40-55psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1303-1696kPa (189-246psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

18°C (64°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

35-60%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

276-379kPa (40-55psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1310-1709kPa (190-248psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

18°C (64°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

Above 60%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

290-400kPa (42-58psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1358-1765kPa (197-256psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

19°C (66°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle rowSpan=3>
<Font size=1>

30-35°C (86-95°F)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

Below 30%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

317-434kPa (46-63psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1544-2006kPa (224-291psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

22°C (72°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

30-50%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

324-441kPa (47-64psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1558-2034kPa (226-295psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

22°C (72°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

Above 50%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

365-510kPa (53-74psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1675-2179kPa (243-316psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

26°C (79°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle rowSpan=3>
<Font size=1>

36-41°C (96-105°F)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

Below 20%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

400-552kPa (58-80psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1917-2503kPa (278-363psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

28°C (82°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

20-40%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

393-546kPa (57-79psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1910-2496kPa (274-357psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

28°C (82°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

Above 40%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

400-552kPa (58-80psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

1910-2496kPa (277-362psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

28°C (82°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle rowSpan=2>
<Font size=1>

42-46°C (106-115°F)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

Below 20%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

448-621kPa (65-90psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

2172-2834kPa (315-411psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

31°C (88°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

Above 20%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

462-634kPa (67-92psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

2220-2896kPa (322-420psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

32°C (90°F)</P></TD></TR>
<TR>
<TD vAlign=center align=middle>
<Font size=1>

47-49°C (116-120°F)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

Below 30%</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

531-731kPa (77-106psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

2379-3116kPa (347-452psi)</P></TD>
<TD vAlign=center align=middle>
<Font size=1>

43°C (109°F)</P></TD></TR></TBODY></TABLE>

[PARAGON]

I would just leave this alone Jonahs. I'll ignore the smartass google remark.

The table above is for the '03s A/C system. It is the max temp given ambient air temperature and relative humidity. You asked Intimidator what humidity had to do with it. Then proceeded to tell everyone they were wrong when they tried to explain it. Now you fling an insult and then attempt to cover up and say that the original question had nothing to do with humidity.

I guess all of the automotive climate engineers should just bow to your car wash experiments and forget the science behind their A/C performance table.

[LasVegas]

Not trying to cover anything but God man, get a sense of humor. They're those that live in the engineer world and those in the practical world. And it wasn't an insult. Get the http://www.elcova.com/infopop/emoticons/icon_biggrin.gif. Sheesh