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Neon AC compressor cycling
Chrysler Dodge, Plymouth, Jeep, Eagle, etc info/talk (rec.autos.makers.chrysler)
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#21
 
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Re: Neon AC compressor cycling -
07-06-2004
, 09:02 AM
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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. |
ballast resistor is a voltage divider, I asked him; "where the
voltage is divided to?"
Still waiting.
#22
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"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. By the way having previously lived in upstate New York for many years where 90+ inches of snow per winter was common, I would say that cold air does a pretty good job of holding moisture :0) |
That's OK, he's never had a carload of just-off-ice hockey players in
his car at -25C. They is plenty o' humidity there! And you are sure
glad to get some dehumidification from the AC.
And I know it happens, especially in the first gen. Neons because you
can feel the AC compressor engaging when your are cruising along the
highway.
Dan
#23
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PC Medic 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. By the way having previously lived in upstate New York for many years where 90+ inches of snow per winter was common, I would say that cold air does a pretty good job of holding moisture :0) That's OK, he's never had a carload of just-off-ice hockey players in his car at -25C. They is plenty o' humidity there! And you are sure glad to get some dehumidification from the AC. And I know it happens, especially in the first gen. Neons because you can feel the AC compressor engaging when your are cruising along the highway. Dan |
#24
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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. |
reputable companies.
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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? |
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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? |
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Read up on "Dew Point." |
that clouds can form at temps well below freezing. Read up on "airframe
icing."
Matt
#25
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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. |
Matt
#26
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In article <b06ke0h132ef40b8172718d6ev22n0ac7r (AT) 4ax (DOT) com>, nospam.clare.nce (AT) snyder (DOT) on.ca wrote: And what is the humidity/dew point when the snow on your boots melts into the floor mats, and the heater evaporates it back out? Are you suggesting that the low pressure switch reacts to events present inside the passenger compartment Clare? But to answer your question, if you have snow on your boots, you can be assured that the dew point is 32 or below since dew point can not be higher than ambient temperature. FWIW, a dew point of 32 is not considered to be high humidity. 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. |
freezing, underhood temps well above freezing, and yes, the compressor
DOES come on with the heater in the defrost position, or with the AC
turned on in the recirculating mode. 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
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When the A/C is functional I do not have the condensation problems I have when it is not - One MAJOR reason I fixed the AC on the Trans Sport last year, and the New Yorker 3 years ago. (and why I'll likely have to fix the daughter's Neon this year) Then it will be a good exercise for you to switch on the AC and then go observe the compressor clutch to see if it's engaged on the next 10*F day. (hint; if it's engaged, you didn't fix it correctly) |
#27
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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?" |
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.
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Still waiting. |
#28
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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." |
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 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.
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 - I mean it is not *always* below
the compressor lockout temperature, and certainly not for months at a
time. And for those places that are that cold continuously for months
at a time, well, that's life. Point is that a benefit that serves most
of the owners very well is derived.
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. 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).
Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")
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#29
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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... |
schematic of a voltage divider). Didn't even have to explain it for it
to be obvious.
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! =-----
#30
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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. |
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).
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By the way having previously lived in upstate New York for many years where 90+ inches of snow per winter was common, I would say that cold air does a pretty good job of holding moisture :0) How can that be if it's falling out of the sky and collecting on the ground? |
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
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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? |
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... |
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