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Neon AC compressor cycling
Chrysler Dodge, Plymouth, Jeep, Eagle, etc info/talk (rec.autos.makers.chrysler)
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#31
 
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Re: Neon AC compressor cycling -
07-06-2004
, 08:24 PM
| nospam.clare.nce (AT) snyder (DOT) on.ca wrote: On Tue, 06 Jul 2004 13:02:27 GMT, Neil Nelson <nonelson (AT) sbcglobal (DOT) net wrote: Well, it's been a couple of years since Clare claimed that a ballast resistor is a voltage divider, I asked him; "where the voltage is divided to?" A standard ballast resistor in series with an ignition coil IS a voltage devider. The [ballast resistor] sees part of the voltage, the coil sees the rest. Get a voltmeter and try it. Or to be SURE you can see it, get two. Put one meter across the resistor, and one across the coil, and ground the negative side of the coil (like closing the "points"). You will see, on a typical system, (lets say on a vehicle using a Napa IC107 coil and its associated resister) 5 volts across the resistor and 7 volts across the coil with 12 volts supplied... Yep - the load (coil) acts as the bottom resistor (in the traditional schematic of a voltage divider). Didn't even have to explain it for it to be obvious. |
pictures (like a comic book) isn't even enough.
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Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x") -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#32
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"Neil Nelson" <nonelson (AT) sbcglobal (DOT) net> wrote in message news:nonelson-305E09.07591106072004 (AT) newsclstr01 (DOT) news.prodigy.com... In article <jZuGc.22711$mN3.18235@lakeread06>, "PC Medic" <NOT (AT) home (DOT) net> wrote: "Neil Nelson" <nonelson (AT) sbcglobal (DOT) net> wrote in message news:nonelson-C491E5.21312605072004 (AT) newssvr28 (DOT) news.prodigy.com... In article <ccctsn018l9 (AT) enews4 (DOT) newsguy.com>, Matt Whiting <whiting (AT) chilitech (DOT) net> wrote: Well, I doubt that virtually all of the car makers would recommend a practice that didn't do anything. Your "virtually all" is more like an old wives tale. I know my compressor will run in fairly cold weather if I simply select defrost. Well Matt, what exactly is "fairly cold?" 60*F? 50*F? 40*F? 35*F? As air cools it becomes more dense, if the air is more dense it can not hold as much water vapor, if it can't hold much water vapor, what is the point of running the AC compressor in an attempt to dehumidify the intake air? Read up on "Dew Point." Well both our Camaro (GM) and Caravan (Chryco) owner manuals state that the compressor will automatically engage when defrost is selected to provide more efficient operation. Yup, automatically. (think about that) I never said that the AC compressor wouldn't engage when defrost was selected. But that doesn't mean that it will always come on no matter what the outside temperature is, because it won't if the temperature is low enough. Well what do *you* consider low enough. I know from my years in New York that that the compressors on my newer vehicles engaged when in the defrost mode even in some pretty damn cold whether (as in well below freezing). "southerners" should not pretend to be authorities on things they know |
(particularly if non pilots) should not advise pilots on things like
dew point.
#33
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Your "virtually all" is more like an old wives tale. Typically, old wives tales aren't writting into owner's manuals from reputable companies. |
the owners manuals from both my 95 Dakota and 98 Intrepid.
No mention what-so-ever in either owners manual WRT running the
AC system in winter for any of the reasons that you cite.
Since Bill Putney has a vehicle almost identical to one of these,
I invite him to check -his- owners manual to see if there is any
mention of running the AC in winter to keep the seals lubricated.
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I know my compressor will run in fairly cold weather if I simply select defrost. Well Matt, what exactly is "fairly cold?" 60*F? 50*F? 40*F? 35*F? 20F |
system will be 18.4 PSI, a typical R-134a system low pressure cut
out switch will open at 22 PSI, for an R-12 system at 20 degrees
Fahrenheit, the system will be at 21.0 PSI, a typical R-12 low
pressure cut out switch will open at 26 PSI.
Guess what isn't going to happen at 20 degrees Fahrenheit?
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| As air cools it becomes more dense, if the air is more dense it can not hold as much water vapor, if it can't hold much water vapor, what is the point of running the AC compressor in an attempt to dehumidify the intake air? Air can hold enough water vapor to form fog at subzero temperatures. Read up on "Dew Point." I'm a pilot and know a fair bit about dew point. I know enough to know that clouds can form at temps well below freezing. Read up on "airframe icing." |
Dodge/Plymouth Neon?
#34
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Yup, automatically. (think about that) I never said that the AC compressor wouldn't engage when defrost was selected. But that doesn't mean that it will always come on no matter what the outside temperature is, because it won't if the temperature is low enough. What's "low enough?" |
below the low cut out switch's trip point, for an R-12 system, 30
degrees will put the system pressure below the low cut out
switch's trip point.
System architecture will usually have either a low pressure
switch mounted in a low pressure line under the hood, a
evaporator temperature switch mounted in the evaporator case or
in the case of the Neon (and many other Chry-Co vehicles) both
wired in series to the compressor clutch.
#35
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What causes the heavy condensation on the windshield/backlight when you leave the car sit? Heavy condensation when the car sits would suggest temperatures well above freezing, which is not what was being claimed when Matt suggested running the AC in winter. Incar temperatures far above frezing, and outside temp of well below freezing, underhood temps well above freezing, |
Clare's planet. Go back to the part where you claimed "heavy
condensation on the windshield/backlight when you leave the car
sit?"
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and yes, the compressor DOES come on with the heater in the defrost position, or with the AC turned on in the recirculating mode. |
up...
<good gawd>
....and understanding this discussion....
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Can not vouch for coming on in standard fresh air mode, but I'm sure it has. (on my New Yorker and on the Trans Sport |
Just take those laws of physics and chuck 'em right out the
window.
#36
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On Tue, 06 Jul 2004 13:02:27 GMT, Neil Nelson <nonelson (AT) sbcglobal (DOT) net wrote: In article Pine.GSO.4.58.0407060001430.15475 (A...ngin.umich.edu>, "Daniel J. Stern" <dastern (AT) 127 (DOT) 0.0.1> wrote: Well, y'know, Neil, in Clare's little world -- I caught myself wondering the other day what color the sky is there -- all kinds of things are possible. The normal laws of physics and function just don't apply. Evaporators and radiators require replacement just because the condenser's got a leak, in his world, so surely it must be within the realm of possibility in that bizarre place for an MVAC LPCO to detect the dew point inside the passenger compartment. Well, it's been a couple of years since Clare claimed that a ballast resistor is a voltage divider, I asked him; "where the voltage is divided to?" A standard ballast resistor in series with an ignition coil IS a voltage devider. The coil sees part of the voltage, the coil sees the rest. Get a voltmeter and try it. Or to be SURE you can see it, get two. Put one meter across the resistor, and one across the coil, and ground the negative side of the coil (like closing the "points"). You will see, on a typical system, (lets say on a vehicle using a Napa IC107 coil and its associated resister) 5 volts across the resistor and 7 volts across the coil with 12 volts supplied. If you are still waiting for the answer it's because you didn't read your mail back then. |
Still waiting.
um, Clare...
Dropping voltage doesn't mean that it has been divided.
#37
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As air cools it becomes more dense, if the air is more dense it can not hold as much water vapor, if it can't hold much water vapor, what is the point of running the AC compressor in an attempt to dehumidify the intake air? Read up on "Dew Point." That is *exactly* how air conditioning lowers humidity - it cools the air before it gets to the heater, even more moisture condenses out (that "dew point" thing), then it gets heated up, so you end up with even dryer warm air. It might seem that cooling it only to have to heat it again would be counterproductive. However, the reality is that under many situations, the total effect of pre-cooled and then heated is greater than simply heating if the purpose is to keep moisture from condensing onto the windshield and decreasing visibility (it's a safety thang). |
the ambient air temperature is already low and the dew point is
so low that there is very little moisture content to begin with
(like Matts 20*F cite)
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The only reason that the mfgrs. put a limit on outside temperature before the compressor is disabled is to protect the compressor from damage. Otherwise, the a.c. would be allowed to run in defrost mode at the colder temps. |
where the AC compressor is not allowed to run because the system
pressure would be so low so as to lock the compressor out.
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In most geographical areas, a.c. inherently runs enough during the winter months to get the benefits to the compressor that Matt talks about from being in the defrost mode - |
air conditioning during the winter -months- but that is not the
question, the question concerns winter -conditions-, i.e., cold
temperatures, cold enough that the ambient temperature puts the
system pressure below the low pressure switch's cut out point.
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I mean it is not *always* below the compressor lockout temperature, and certainly not for months at a time. |
and Montana and New York and Alaska and probably quite a few
other states not to mention large parts of Canada.
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And for those places that are that cold continuously for months at a time, well, that's life. |
premise.
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Point is that a benefit that serves most of the owners very well is derived. |
part of Matt's premise.
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Years ago, when a.c.'s were not as common in autos, and the controls were truly manual without computer over-rides and complex algorithms, and the a.c. was not integrated into the defrost mode, the manufacturers indeed did advise the public to run the a.c. occasionally during the winter months for the reasons Matt cited. |
directed at owners of much older vehicles.
Seen many 1962 Dodge Noens?
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With the automatic operation in defrost mode, it isn't necessary to give that advice, and you don't hear it anymore, and the public is less informed about the situation altogether (i.e., very few people are even aware that the compressor runs automatically in the defrost mode, even if they know what a compressor is). |
you're saying that they don't.
I'll side with you on this one but do me a favor, check the
owners manual for your Concorde and see if there's a specific
recommendation about running the AC compressor in the off months
to keep everything lubed.
One last thing... On those old cars where it was recommended to
run the AC in winter, why is it that evaporator freeze up (as in
blocked solid by ice) was not a concern?
Is it possibly because under winter conditions, there wouldn't be
enough moisture content in the air for it to be a concern?
(round and round we go)
#38
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Yup, automatically. (think about that) I never said that the AC compressor wouldn't engage when defrost was selected. But that doesn't mean that it will always come on no matter what the outside temperature is, because it won't if the temperature is low enough. Well what do *you* consider low enough. I know from my years in New York that that the compressors on my newer vehicles engaged when in the defrost mode even in some pretty damn cold whether (as in well below freezing). |
them.
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How can that be if it's falling out of the sky and collecting on the ground? Certainly isn't *DRY* ice coming down! Where do you think all that moisture that is creating the snow is coming from...the humidity in the air. When humidity level and dew point meet ...viola! moisure. Warm temp = Rain Cold temp=snow |
holding moisture. Snow is not moisture held in the air, it has
already precipitated out.
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Or are you now saying that running the AC in the defrost mode will somehow help clear a windshield covered in snow? It certainly helps clear any fog/frost that may have formed on the inside of the glass and defogs much quicker. |
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I'm really just trying to understand how poorly ya'all have thought this out... Likewise |
#39
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For some of the thick skulls on this group explaining it, with pictures (like a comic book) isn't even enough. |
as 'divided' voltage. (yes I did)
here guys;
http://www.allaboutcircuits.com/vol_1/chpt_6/1.html
scroll down about 1/3rd of the page.
#40
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"southerners" should not pretend to be authorities on things they know nothing about - like winter, and heaters, and frost. And they (particularly if non pilots) should not advise pilots on things like dew point. |
fly back in the 70s.
On the other hand, if you know the maximum altitude ever achieved
by a Dodge/Plymouth Neon, please tell us. Otherwise, you're
still as full of shit, still as washed up as you always have been.
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