I'm new to the forum and hoping you guys can help me keep from taking my out of warranty van to the dealership. I have a 2005 Dodge Grand Caravan that has intermittant issues with the air exiting from the vent ducts, then changes to the defrost and floor, and then back to the vent. All within approx 10 sec. The vent indicator light stays lit and does not change from defroster to vent and etc. The rear air is unaffected. The engine rpm makes no difference when it is acting up and changing from vent to vent. This is very intermittant and does not stay broke. I don't know if this would be a vacuum issue or something else. Any ideas?
Thanks, Kevin

 

Welcome to DFAUTOMATIC TEMPERATURE CONTROL (ATC)
Comfort temperature or perceived temperature is affected by air flow, sun levels on exposed skin, etc. The air temperature may be higher or lower than the comfort temperature. The automatic temperature control (ATC) system uses two infrared sensors in the instrument panel center stack to measure the temperature of the front occupants in order determine their comfort level relative to their selected comfort temperature. The integral HVAC computer adjusts temperature and air flow rates to maintain the customer-perceived comfort temperatures. The air temperature in the passenger compartment may be slightly higher or lower than the comfort temperature at any time. For instance, on sunny summer days the air flow will probably be cooler than the comfort temperature; on cold or cloudy days and at night it will probably be slightly warmer.

The Three-Zone ATC system uses the infrared sensors located in the instrument panel center stack along with an offset calibration strategy to meet the comfort requirements of the rear seat occupants.

FRONT CONTROL PANEL
AUTO HI/LO – This system features two sets of automatic control logic that allow either a rapid cool-down rate or a somewhat slower cool-down rate with less fan noise. HI-AUTO controls the system to reach its assigned temperature quickly with a higher fan speed. LO-AUTO controls the system to reach its assigned temperature somewhat slower with less fan noise. Both modes will automatically engage auto recirculation.
DEFROST – The defrost function must be manually selected to direct air flow to the windshield to remove fog or ice. The ATC system cannot automatically sense the presence of fog or ice on the windshield.
RECIRC – The RECIRC button will close the air inlet door. If the system is in auto recirc (indicator being displayed automatically), pressing the manual recirc button will disable the auto recirc function until one of the auto keys are pressed or the ignition is cycled. If Auto HI/LO is pressed while manual recirc is active, manual recirc will be deactivated.
REAR WINDOW DEFOGGER – Pushing the button sends a PCI bus message to the intelligent power module which controls the rear window defogger and side view mirror (if equipped) circuitry. The defogger function will be active for 10 minutes and can be turned off by a switch press. The defogger will function while the control is in the ON mode.
FAN/MODE – The Fan and Mode ***** have 17 manual selectable positions. Manually changing either of the rotary ***** for mode or fan speed settings makes control of that blower motor manual. If only one is changed manually, the other remains under automatic control. Pressing the HI-AUTO/LO-AUTO rocker switch restores full automatic control.
BLOWER DELAY TIMER – The word DELAY is displayed at start-up to signify that the system is waiting so that cold air will not be blowing. This tells the operator that it is unnecessary to turn the system off, raise the temperature setting or turn the fan speed setting down to prevent cold air from blowing. A countdown in minutes and seconds until the engine is warm enough to begin delivering heat to the passengers alternates with the DELAY message at 25 second intervals. This countdown is based on actual measurement of the rate of engine coolant temperature change. During the delay time, mix mode is selected and the fan operates at a low speed to keep the windshield fog free.
REAR CONTROL (Three-Zone only) – When the Rear System control **** is moved to the OFF position, there will be a delay of approximately 1 second before the system actually turns off. This delay is to prevent an undesired blower dropout if the **** is moved through OFF to the other selections.
REAR CONTROL PANEL – THREE ZONE ATC SYSTEM
Primary control of the rear compartment heating-A/C system for the Three-Zone ATC system is in the instrument panel center stack. This control allows the driver to turn the rear heating-A/C system off, or allows the intermediate seat occupants control of the rear system by switching to the REAR position, or provides fully automatic control based on the temperature setting shown on the front control display.

REAR CONTROL – Selecting automatic control of the rear unit at the instrument panel, illuminates a Locked Padlock in the rear control panel display. Selecting REAR activates the rear control panel and the Padlock then appears unlocked.
FAN **** – The rear fan control has Off and AUTO positions and a range of manual speed settings that override the AUTO setting.
MODE **** – The mode control allows intermediate seat occupants to manually override the automatic mode and select any balance of air flow between overhead and floor outlets from full overhead to full floor.
SET TEMP – The rear set temp control will operate identical to the front controls. If the front control rear set temp button is pressed simultaneously with the rear control head, then the front control head press events shall have priority, i.e. if the front user presses Rear Set Temp down and the rear user presses Set Temp up, then the rear set temp will decrease.

 

Thanks Master Tech for posting the info. I've owned this van since it was new in 2005, so I'm somewhat familiar with it's basic operations. This issue of the air changing to different vents, usually upon startup is something new it's doing. On a hot 90 degree day when the system is set to auto high it will intermittantly switch to defrost and then floor and then out the correct vent. (a few times, one right after the other) When failed and starts switching to the defrost, it is very obvious because the blower is running at max speed when calling for maximum cooling. (It's loud when it jumps to defrost or the floor) The dealer said that they could hook up a scanner or something to see what it's done in the past but no guarantees. I don't know if that auto climate system reports failures or trouble areas or not. Do you know?
Thanks- Kevin.

 

Master Tech, I think I didn't reply to your post properly so I will copy and past it here.
Thanks Master Tech for posting the info. I've owned this van since it was new in 2005, so I'm somewhat familiar with it's basic operations. This issue of the air changing to different vents, usually upon startup is something new it's doing. On a hot 90 degree day when the system is set to auto high it will intermittantly switch to defrost and then floor and then out the correct vent. (a few times, one right after the other) When failed and starts switching to the defrost, it is very obvious because the blower is running at max speed when calling for maximum cooling. (It's loud when it jumps to defrost or the floor) The dealer said that they could hook up a scanner or something to see what it's done in the past but no guarantees. I don't know if that auto climate system reports failures or trouble areas or not. Do you know?
Thanks- Kevin.

 

I own a 2001 se but all the lights went out in it except the far right one. Is there any way to replace the lights? I have it out of the van but cant get the back off of it.

 

disconnect the battery for 10 mins and see if it stops.

 

I'll try it. It may take a week or so before I can say it helped or not because of its intermittant nature. Thanks very much for your time Master Tech!!
-Kevin

 

Hi Kevin
Sorry I was out of town,If you still have warranty on the van. I would have the dealer hook up the DRB3 and ck for stored or active codes in hvac system.

 

Master Tech,

I have had this exact issue on my 2007 Grand Caravan. It would change vents several times and then stop on the selected one (most of the time). Eventually, the selector would no longer change vents, ever. It was stuck on the "normal" in your face vents. I just disconnected the battery to reset an error code for the EGR valve that I replaced and, voila! It works again. Is this a known issue, and how can I fix it?

 

I've been searching for an answer for this for quite some time now. I own a 2007 Grand Caravan. For whatever reason, the air exiting the vents in the rear of the vehicle is uncomfortably hot. Doesn't matter what temperature we set the vents to, the temperature never changes...even with A/C on. The temperature controls for the front of the vehicle seem to work fine, to include A/C. The air blowing out in the back is DEFINITELY not the same temperature as the air outside. It's being heated before it enters the vehicle. For now, our fix has just been to drive with the front vents on. Trying to get this fixed before the dreaded summer months hit. Anyone seen this before?