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Jeep Grand Cherokee A/C Heating Ventilation

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Comments

  • there is a relay and wire right under dash at passengers feet area.
    you will see wires and a connector. tap with hammer this is the controls box also jiggle wires that go into the white plastic connector.

    I have had the same problem and fixed it bye rewiring the white connector
  • I was having blower motor problems and traced it back to the resistor connector. When the motor stops working, if I move the connector wiring to the resistor around it will turn back on. So I bought the wiring repair kit and redid the wires and connector to the resistor but it is still not working. the old connector had melted the plastic away from the resistor cover too. Could that affect the connection? Now I can't even move the wires around for any heat and it is freezing.
  • msa3msa3 Posts: 6
    My 2004 Jeep Grand Cherokee intermitently blows warm and cold air at the same time. The dealer said it was a bad door in the dash and removed the dash and replaced it once under warranty and it still is doing the same thing and the warranty is over. When it does this all you have to do is shut the engine off and start it again and the problem goes a way until it happens again. It sometimes takes days or weeks to happen again.

    Also, something that just started happening is when you turn the vehicle off you hear what sounds like a vent door opening and closing coming from the passenger side under the dash.
  • blendorblendor Posts: 23
    If you have the Automatic Zone Control system (AZC) with the dual control system.

    Before you do anything else!

    The first thing you should do is use the AZC fault code system.

    To read the fault codes:
    1. Turn on the ignition switch.
    2. Turn on the AZC system. The temperature settings should be displayed for both sides.
    3. Simultaneously hold down the AC and the Re-Circ buttons.
    4. Then turn the driver’s side temperature (Left) control knob to the right (CW) one click.
    5. Then release the AC and Re-Circ buttons.

    If there are no fault codes, the “00” display value will remain in the window.
    If there are any codes, each will be displayed for one second in ascending numerical sequence (note: no effort is made to display faults in the order they occurred). The left side set temperature display will be blanked and the right side set temperature display will indicate current and historical codes (8 historical max) presently active.
    Once all codes have been displayed, the system will repeat the fault code numbers. This will continue until the left side set temperature control is moved at least one detent position in either direction, by pressing both the A/C and Recirc buttons at the same time, or the ignition is turned off.

    Also describe any symptoms you are having with your heating system.
    Like - Are you getting a good air flow thru your vent outlets?
    Can you direct the air flow to the different outlet vents?

    Post your fault codes and symptoms or send a message to Blen Dor.
  • msa3msa3 Posts: 6
    The code is 54. The cold and warm air coming out of the floor vents at the same time onnly happens about once every few months. The sound of a door opening and closing also happens intermitently. Is it possible it could be the heat control switch or something else causing the door to open and close?
  • blendorblendor Posts: 23
    The code 54 is a blend door problem.

    But I am confused with the description “Cold and warm air coming out of the vents at the same time”.
    Would that be cold air coming out of the vents on one side of the vehicle and warm air coming out of the vents on the other side of the vehicle?

    The sound of the doors opening and or closing is most likely the actuator motor putting tension onto the blend doors during the calibration process.
    Briefly, the calibration process happens every 20 ignition cycles, it is the computer finding the location of the two openings, which will let the computer know where to position the blend doors according to the temperature that was set on the display.

    Does the heating system work good, between the once every few months cold and warm air problem?
  • msa3msa3 Posts: 6
    The heating system does work very well. The cold air comes out of one floor vent and the heat comes out of the other,

    This happens when the heater is on, not when the air is on. When it happens all you have to do is turn the ignition off and restart the jeep and the problem corrects itself everythime.

    Also, when the door opens and closes it continues to happen after you shut the ignition off for awhile.
  • blendorblendor Posts: 23
    Which side of the vehicle does the heat come out?

    The door noise continuing after the ignition is turned off is a normal condition. As there is still current flowing after the ignition is turned off, the computer and other items like the clock, etc. are not controlled by the ignition switch.
  • msa3msa3 Posts: 6
    I am not sure which side the heat comes out of. It has been about a month since it did it. I will let you know as soon as it does it again. As far as the noise of the door opening and closing under the passenger side of the dash, it has never done that before? It just started doing that last week once and awhile. When it does it you can hear the creaping of the door opening and closing non stop for awhile.
  • Blend door failure is common on the GC and what you are observing is not unusual. The computer system goes through a calibration routine every twenty times the GC is started to "learn" the position of the blend doors and re-circ door. The creaking and straining noises you are are this calibration routine.

    The only elements in the GC HVAC system that differentiates between driver's and passenger side are the blend doors and a difference between passenger and driver's is usually an indication of blend door failure. Reading the HVAC codes will give you a definitive diagnosis.

    The intermittent operation is most likely a symptom of the system in the midst of failing. The doors are not totally broken...yet, but they will get there over time. Sorry for the bad news, but this is a flaw in the system design and replacing the doors is the only option.

    HeaterTreater
  • blendorblendor Posts: 23
    As we discussed previously you do have the #54 fault code which is a blend door problem.

    The sounds coming from the dashboard are most likely from the blend door shaft that has partially broken and is now making noises during the calibration process and or just the broken blend door moving during the temperature adjusting process.

    It sounds like the blend door problem is getting worse and possibly the other blend door will be breaking in the near future.

    Let me know what happens with cold air from one side and the heat for the other.
    It sounds like a blend door problem, but if you need more help,

    Search for the Blen Dor
  • msa3msa3 Posts: 6
    Can you provide the parts and procedure if I need to replace the doors and not lose the heat control for the passenger side?

    I believe you indicated this would involve removning the dash. I have done some extensive repairs to my sons BMW in the past with instructions he got off the internet.

    I am pretty mechanically inclined and have the time to do it as long as I have the step by step process.
  • steverstever Viva Las CrucesPosts: 41,990
    There are a few products available on places like eBay that offer repair kits that don't involve removing most the dash like the dealer fix does. Just some of the dash. :)

    A few of the vendors have come to CarSpace simply to tout their product, which is against our membership rules. You can find them easily enough with a net search if you decide to go that route.

    Moderator
    Minivan fan. Feel free to message or email me - stever@edmunds.com.

  • My 2003 apperars to have a bad temperature control rotary knob. (This vehicle does not have dual-zone control). I usaully get a blend of hot/cold air regardless of where I have the knob set. However, if I press on the knob or jimmy it a bit, the damper will move and air will be supplied at the desired temperature. Fan blower, mode selector, heater and AC all work fine...this is just a temp control issue...

    I've been reading this forum a while, but I have not seen a post describing a similar problem. Has anyone else experienced this, and what is the difficulty and $ of replacing this control?
  • The knob may be slipping and you will have to remove it and see if the connection is cracked. This happens a lot on the Ford F150's, but I'm surprised on the GC. It's just a variable resistance switch that the knob is turning and there shouldn't be enough resistance to strip the knob unless someone is trying to turn it past the end points.

    You can fully open the glove box and examine the actuator motor to the left of the glove box opening. When you turn the temp knob, the motor should move. The system is under computer control and will shut that motor down when it detects a system fault, so failure of the motor to turn does not necessarily mean a bad motor.

    The motor can be removed by removing two philips screws and pulling the motor straight back. Examine the motor connection and blend door axle to see if there is damage. The white axle going into the plenum box has a limit pin extending radially from the axle that is constrained between two stop points molded into the plenum box. Check that the limit pin is not broken and that you can turn the blend door axle easily with your fingers. You should be able to manually switch between heat and no heat with your fingers. You can check the motor with a 9V battery and a snap connector. Just touch the wires to the two terminals and the motor should turn, and reverse when you switch the wires.

    From your description, I'd be concerned with checking the knob closely. If the connection is cracked, you should feel a "bump" in the knob when you turn it. This would be a sign of a cracked connector that is not engaging the switch. You should also be able to feel an end point to movement. If the knob spins 360 degrees, the connection is broken. If nothing else, remove the knob and use a pair of pliers... Just kidding, a broken knob should be easy to fix with epoxy and a couple of loops of wire around the knob connection.
  • Hey, I have a 2003 Jeep Grand Cheorekee Limited and for awhile now I havn't had heat but the a/c worked fine. But lately my a/c only works when driving fast. The faster I drive the more cool air comes out but when I'm idlle, nothing comes out. I can't control the air ither, if I drive fast the a/c is blowing fast and I can't turn it lower it blows fast if its on and I'm driving fast (50 mph +). I was wondering what the problem could be.
  • This sounds like a problem with the re-circ door. This door has two positions, block external intake vent forcing air to be pulled in from the internal vent, and block internal vent forcing air to be pulled in from the external vent. When the door breaks, it can fall down or hang in the center position leaving both the external vent and internal vent open. At highway speeds, air will flow into the external vent and out of the internal vent...like having a window rolled down all the time. In your case, it sounds like the door may be broken and has fallen down and is partially blocking air intake to the fan motor. You can see the intake port behind the glove box or run another simple test. With the fan on full blast, check the air flow into the external vent between the hood and windshield. With re-circ off, you should feel air being pulled into the vent, and the flow should stop with re-circ on. There are aftermarket repairs to address and fix the re-circ door and a video on youtube.

    HeaterTreater
  • blendorblendor Posts: 23
    Giving your symptoms is only a part of the diagnosing process.

    The 99/04 Jeep GC Limited has a fault code system you can read. The fault code system is an excellent place to start the diagnosing process.

    Since you have the Automatic Zone Control system (AZC)
    The first thing you should do is check the AZC fault codes.

    To read the fault codes:
    1. Turn on the ignition switch.
    2. Turn on the AZC system. The temperature settings should be displayed for both sides.
    3. Simultaneously hold down the AC and the Re-Circ buttons.
    4. Then turn the driver’s side temperature (Left) control knob to the right (CW) one click.
    5. Then release the AC and Re-Circ buttons.

    If there are no fault codes, the “00” display value will remain in the window.
    If there are any codes, each will be displayed for one second in ascending numerical sequence. Once all codes have been displayed, the system will repeat the fault code numbers. This will continue until stop the process by moving the left side set temperature control one click in either direction, by pressing both the A/C and Recirc buttons at the same time, or the ignition is turned off.

    Record all of the fault codes and also describe any symptoms you are having with your heating system.
    Like - Are you getting a good air flow thru your vent outlets?
    Can you direct the air flow to the different outlet vents?

    Post your fault codes and symptoms.
    I’ll interpret them for you and advise you on how you could repair your heating system.

    Blen Dor
  • Certainly reading the codes is not going to hurt anything, but you already have most of the information that you need. Assuming that the heater lines are getting hot and the fan is blowing, lack of heat on either or both sides of the GC is a 99.9% indication of a broken blend door. The problem is pervasive on the GC and almost a knee jerk diagnosis. Reading the code and getting a 54 and/or 56 will take you from 99.9% to 100%

    Virtually every GC in your year range is going to throw a 52 code for re-circ door travel too large. The re-circ door is larger and stronger than the blend doors and will "bend" before it breaks. The computer system will detect that the movement is out of spec, but this doesn't necessarily indicate that it is broken. It WILL break over time once you see the 52 code, but it can go another year or so with perfectly normal operation even with the code. The physical examination tests that I posted in the previous answer will tell you definitively what's going on with the re-circ door. The code will only alert you that the door is in the process of breaking and could possibly be broken already. I'd suggest that you just skip the re-circ door code and go straight to physical examination. Guys trying to sell you something based on just reading codes are either uniformed or scamsters.

    HeaterTreater
  • Thanks for the advice. I did the fault code process and got 52, 54 and 56.
  • My question is what should I tell the people at the car repair shop in how to fix my car so I am not overcharged or charged for things I dont need done.
  • Your mechanic at the car repair shop will most likely want to follow the dealer recommended repair for the blend doors. This requires removing the steering wheel, steering column, complete dash, evacuating the AC refrigerant system, draining the radiator and finally removing the plenum box so that it can be opened into two halves and the blend door replaced with more OEM plastic that will break again. Expect the price to range between $800 and $1200. While it's apart, it's probably a good idea to make sure that both the blend doors and re-circ door are replaced, and check the heater core and AC evaporator core for any signs of corrosion. After going this far, it's not a bad idea to just replace both of these components.

    The alternative to the dealer recommended process is an aftermarket solution that cuts into the box with a dremel tool and replaces the door with metal at a fraction of the dealer cost. The solution has been successfully deployed on thousands of GC's and is a proven reliable repair. A video of the process is available on youtube and you can search Grand Cherokee blend door to find it. Certainly the aftermarket fix could be installed by a "mom and pop" garage, but most likely you will need to find and order the components and specifically push the shop to execute the fix you choose. There is always a little reluctance to do anything that is not a standard Chrysler repair process. Note that the process is relatively simple and you might well decide to do it yourself.

    HeaterTreater
  • Thanks for all this feedback. So what would you reccommend I tell the mechanic when I bring my car into get fixed, so I do not incur any costs I shouldnt be incurring.
  • Your mechanic will most likely not have any solution for you other than replacing the blend door per the factory recommendation. As outlined above, this is an expensive proposition. There is an aftermarket alternative that you could either install yourself or take to the mechanic with instructions and a request that he do the installation. You will have to do the searching yourself since this forum does not condone direct links to aftermarket products.

    HeaterTreater
  • blendorblendor Posts: 23
    Glad you took my advice and read your fault codes.
    That has given you an excellent place to start

    Your description in post #316 of the air flow only comes out of the vents when driving and nothing when stopped. That sounds like you could also have a blower problem.

    Can you hear the blower working?
    Can you hear the blower working and no air is coming out of the vents. (When the vehicle is NOT moving) If this is happening – that is a symptom of the broken recirculation door - not a blower motor problem.

    In your previous post #323 your fault codes were 52, 54, 56.
    The #52 is a recirculation door problem. The 54 is the driver’s side blend door problem and the #56 is the passenger’s side blend door problem.

    As you probably already know, replacing the blend doors requires the HVAC box to be removed from the vehicle and taken apart. Most of the labor cost is in process of removing and replacing the HVAC box.

    So about the only thing you could tell the mechanic is that you have read the fault codes and replacing anything more then the recirculation door and the blend doors will require you to visually check the part before giving approval.

    Good Luck
  • I have a 1995 Jeep GC limited with a ATC heat AC system. The blend door motor goes to the hot air extreem and will not return. The blend door motor has a 5-pin connector. My Haynes service manual does not show the wiring diagram for this system. I found an old 2-pin motor made up a polarity revearse switch with a momentary push button to apply power. With the 2-pin motor installed the switch in one position holding the push button for 8-seconds (the time it takes for the motor to travel from one extreem to the other) gets me hot air. Selecting the reverse polarity on the switch haolding the pushbutton for 8-seconds get me very cold air. So my heat and AC systems are working and I am left with a controller problem. I beleive the blend door 5-pin motor should be controlled by the temperature control dial. Could anyone tell me where I could get a wiring diagram for the ATC showing the 5-pin blend dooor motor?
    Mikes_fixit
  • The actuator motor has internal circuitry to determine the extents of movement and feeds that information back to the control system. The problem with this particular motor is that if it is allowed to move unconstrained, it will spin itself to a "point of no return". If the blend door or plastic axle connection break, the motor will turn to a point where the internal electrical wipe tangs make no connection and the motor goes into permanent sleep mode and cannot correct itself. There is an aftermarket kit that replaces the plastic connector between the metal blend door axle and the metal motor connection. The kit also includes complete instructions on how to disassemble the actuator motor, re-index the gears, and bring it back to life. It's next to impossible to find a replacement motor unless you can find one in a junk yard.

    HeaterTreater
  • skinsfan1skinsfan1 Posts: 8
    I have a 2000 Jeep GC limited. Within the last two days, the vents on the driver's side of the vehicle will only blow hot air (with a/c on, or venting fresh outside air). The passenger side works fine. I've scanned this post and wonder if this is a blend door issue? Haven't tried the error codes yet, but will later this week. Any thoughts?
  • blendorblendor Posts: 23
    It sounds like a blend door problem! But, you should always read the fault codes before starting any repairs to the HVAC system.

    Blen Dor
  • skinsfan1skinsfan1 Posts: 8
    I checked the fault code system as you recommended. I received two: 15 and 53. Can you advised on what they mean? and how to fix. BTW the instructions were perfect!!
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