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Car Forum / Dodge / Dodge Cars / March 2007A/C & defroster issue
In my 2004 Dodge Caravan, if the heat-A/C system selector is set to any (ventilation output) position other than defrost, I can slide the temperature selector all the way down (cold) and all I'll get is untreated outside air unless I deliberately hit the A/C button. However, if the selector is turned to the defrost (windshield) position, the A/C will automatically come on if/when the temp selector gets close enough to the cold end. Is there any way to disable this automatic connection between the A/C compressor clutch and the defrost selector? I'd really like to be able to get just plain outside air through my defroster vents and I can always hit the A/C button if/when I want A/C (just like for any other ventilation position on the selector dial). Thanks. > In my 2004 Dodge Caravan, if the heat-A/C system selector is set to any > (ventilation output) position other than defrost, I can slide the [quoted text clipped - 9 lines] > position on the selector dial). > Thanks. The A/C compressor "on" with the defroster button pushed is designed to come on for safety reasons. It is there to pull moisture out of the car and keep condensation off the windshield. There is no setting that will by pass this function. Glenn Beasley Chrysler Tech > The A/C compressor "on" with the defroster button pushed is designed to come > on for safety reasons. It is there to pull moisture out of the car and keep [quoted text clipped - 3 lines] > Glenn Beasley > Chrysler Tech Glenn, i thinnk that design might be a great idea but it is one of the useless desings I know. when people need the put the blower to the defrost mode, usually it is colder outside. People donot want cold air blow to their face so they put it in hot position which disables the AC. so AC runs but does not do anygood. Am i right? On Mon, 12 Mar 2007 14:24:34 -0700, uccoskun wrote: >> The A/C compressor "on" with the defroster button pushed is designed to come >> on for safety reasons. It is there to pull moisture out of the car and keep >> condensation off the windshield. There is no setting that will by pass this >> function. > Glenn, i thinnk that design might be a great idea but it is one of the > useless desings I know. when people need the put the blower to the > defrost mode, usually it is colder outside. People donot want cold air > blow to their face so they put it in hot position which disables the > AC. so AC runs but does not do anygood. Am i right? No, you are not. Did you miss the part above regarding "pull moisture out..."? There's more to A/C than cooling...  Signature"Ubuntu" -- an African word, meaning "Slackware is too hard for me". > > AC. so AC runs but does not do anygood. Am i right? > > No, you are not. > > Did you miss the part above regarding "pull moisture out..."? There's > more to A/C than cooling... The analogy for the pulling moisture is same for the removign condensation. The people put it on heat/warm settign so they bypass the evaporator of AC. So it does not make any difference if you run the AC because no air flows thought the ac part. May I ask you if you put the blower in hot or cold setting when you try to remove moisture in a cold day. You either use AC explicitly to remove moisture on hot days, or you donot care because it does not block your view. Thanks, In article <1173807184.969823.303620@s48g2000cws.googlegroups.com>, > > > AC. so AC runs but does not do anygood. Am i right? > > [quoted text clipped - 7 lines] > the evaporator of AC. So it does not make any difference if you run > the AC because no air flows thought the ac part. The only way the evaporator is going to be bypassed is if you whack at it with a saws-all. I've had plenty of HVAC cases apart, I have yet to see one where the intake air doesn't flow thru the evaporator first. There simply isn't enough space available to have separate air intakes for the heater core and the AC evaporator. > May I ask you if you put the blower in hot or cold setting You don't put the "blower" in hot or cold setting, the blend door determines how hot or cool the output air is going to be. The "blower" settings simply determine how many CFM of air will be moved. > when you > try to remove moisture in a cold day. You either use AC explicitly to > remove moisture on hot days, or you donot care because it does not > block your view. You totally misunderstand how a HVAC system works on any vehicle built in the last 30+ years. AC and heat(defrost) can (and do) run together. > The only way the evaporator is going to be bypassed is if you > whack at it with a saws-all. > I've had plenty of HVAC cases apart, I have yet to see one where > the intake air doesn't flow thru the evaporator first. > There simply isn't enough space available to have separate air > intakes for the heater core and the AC evaporator. Maybe I should take apart my part to see how the air flows through the ducks. > > May I ask you if you put the blower in hot or cold setting > > You don't put the "blower" in hot or cold setting, the blend door > determines how hot or cool the output air is going to be. > The "blower" settings simply determine how many CFM of air will > be moved. Putting blower to hot position is an honest mistake but I expect you/ anybody to figure out what I meant. What I meant is Blending door button (I'm sure it has a special name for it also, but please try to understand what I mean). > > when you > > try to remove moisture in a cold day. You either use AC explicitly to > > remove moisture on hot days, or you donot care because it does not > > block your view. You are kinda right because today even it is at 65s here, I got moisture on my windshield due to rain. So I accept you can get moisture on winshield even on hot weathers. > You totally misunderstand how a HVAC system works on any vehicle > built in the last 30+ years. AC and heat(defrost) can (and do) > run together. Summary: If we follow air from out of the car to inside , The air first passes through AC evaporator, then depending on the positon of blending valve bottun, The air might pass through heater core or bypass the heater core. And then the air is sent directly to air ducks. IS it right? What I thought is, AC evaporator and Heater core are sitting paralel to each other. Blendign valve sends the air either to evaporator or heater core or both depending on setting. and then the air is sent to air ducks. I guess the flow diagram I mention latter is wrong. Did I get it this time. On Tue, 13 Mar 2007 10:33:05 -0700, uccoskun wrote: >> > AC. so AC runs but does not do anygood. Am i right? >> No, you are not. >> Did you miss the part above regarding "pull moisture out..."? There's >> more to A/C than cooling... > The analogy for the pulling moisture is same for the removign > condensation. The people put it on heat/warm settign so they bypass > the evaporator of AC. So it does not make any difference if you run > the AC because no air flows thought the ac part. Wrong again, kiddo. The AC compressor can run regardless of the temperature setting. That's how it works. > May I ask you if you put the blower in hot or cold setting when you > try to remove moisture in a cold day. You either use AC explicitly to > remove moisture on hot days, or you donot care because it does not > block your view. I put my *temp control* on warm, and the *blower* to a speed setting appropriate for the conditions (usually high when first starting the car with moisture on the windshield). Again, the vehicle AC system *will* remove moisture from the air, regardless of whether you have the temperature setting on "cold" or "hot". Signature"Ubuntu" -- an African word, meaning "Slackware is too hard for me". In the old days it was a general piece of wisdom that if your defroster wasn't de-fogging your windshield well enough or fast enough, you activated the A/C, even with the temp on high, to help dry things out. However, since I know that, I would like to be able to *choose* to do that or not. I really would like to be able to get plain fresh air through my defroster vents, but apparently the designers have decided that I'm incompetent and have automated things the way they feel it should be done. Short of rewiring the car from the ground up, including completely re-programming the brain that seems to be in control of *everything*, I guess I'll have to live with the "you're an idiot -- leave everything to us" design... > On Tue, 13 Mar 2007 10:33:05 -0700, uccoskun wrote: > [quoted text clipped - 24 lines] > Again, the vehicle AC system *will* remove moisture from the air, > regardless of whether you have the temperature setting on "cold" or "hot". |
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