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Thread: Help, No Heat Passenger Side only!

  1. #1
    Join Date
    Apr 2000

    Icon313 Help, No Heat Passenger Side only!

    2002 WJ 6cyl.

    no heat just blows cold air on all passenger side vents. From defrost to feet. drivers side works fine.

    what am I looking at, vaccuum lines, solenoids,relays,springs,gremlins?

    I'll search later working on remote start install right now.

  2. #2
    Join Date
    Aug 2003


    I assume it has the AZC! If so, I'd say another blend door broken. Check out the site.
    Many threads on the subject. Probably $800/$1200 to replace actuators and blend doors with the updated parts.
    Hope I'm wrong.

  3. #3


    But I am curious - you say it blows only cold. But when you set the AZC to Hi for the passengr side do you still get cold? Or is it then hot?

  4. #4
    Join Date
    Feb 2003
    east lyme, ct


    yup broken blend door just replaced one cuple weeks ago
    91 chero 37s
    98 5.9

  5. #5
    Registered wusthof's Avatar
    Join Date
    Oct 2004
    Van. BC Canada


    Hope you have warranty.......................happened to me as well - cost me a c-note. As soon as I fell in love with my WJ, I fell in love with the idea of an extended warranty as well ~ luckily I did :2inlove:

  6. #6
    Join Date
    Apr 2000


    Quote Originally Posted by tuckmoss
    But I am curious - you say it blows only cold. But when you set the AZC to Hi for the passengr side do you still get cold? Or is it then hot?

    NO HEAT. Always cold. :mrwave:

  7. #7
    Join Date
    Apr 2000


    Quote Originally Posted by wusthof
    Hope you have warranty.......................happened to me as well - cost me a c-note. As soon as I fell in love with my WJ, I fell in love with the idea of an extended warranty as well ~ luckily I did :2inlove:

    8/80,000 warranty is drivetrain only I believe.

    looks like $200.00 plus a Saturday for.............
    HVAC sub assemblies (most common failures)
    Cold air only / No heat on passenger and/or drivers side / Door travel too small / large
    TSB #24-001-04

    Date: 1/20/04

    Model Year(s): 1999-2004 kmama:

  8. #8
    Join Date
    Apr 2000


    Has anyone gotten creative and done surgery and Dremeled open an access hole to reach in and prop open blend door by hand then patch over the wound?!!

  9. #9
    Join Date
    Apr 2000


    more good is good....... :mypony:

    Home Main menu


    WJ climate controls

    WJ climate systems
    1999-2004 Grand Cherokee models feature either a Manual Temperature Control (MTC) or Automatic Zone Control (AZC). The Automatic control is available only on Limited or Overland models. The manual temperature control HVAC system uses a combination of electrical, and vacuum controls. The Automatic Zone Control HVAC system uses only electrical controls. These controls provide the vehicle operator with a number of setting options to help control the climate and comfort within the vehicle. Refer to the owner’s manual in the vehicle glove box for more information on the suggested operation and use of these controls.

    Both a/c heater control panels are located on the instrument panel inboard of the steering column and below the radio. Both control panels contain rotary-type temperature control knob(s), a rotary type mode control switch knob, a rotary-type blower motor speed switch knob and an air conditioning compressor push button switch. The rear window defogger push button switch is also located on a/c heater control panel. The AZC control panel also features a recirculation push button switch and a vacuum fluorescent display area.

    AZC operation

    The AZC control module uses infrared sensing technology to control occupant comfort levels, not the actual passenger compartment air temperature. Dual infrared sensors mounted in the face of the control unit independently measure the surface temperature to maintain customer-perceived comfort temperature under changing conditions. Dual Zone temperature control provides wide side-to-side variation in comfort temperature to exceed the needs of either front seat occupant. This sensing system replaces interior air temperature and solar sensors used to approximate direct sensing control through complex control programs.

    The AZC system:

    Communicates over the Programmable Communication Interface Multiplex System (PCI) Bus.
    Has dual infrared sensors, mounted in the AZC module face, which independently measure surface temperature to maintain occupant comfort levels.
    Has dual-zone temperature-controls to provide a wide side-to-side variation in temperature to meet the needs of either front seat occupant.
    Can be operated in a manual mode.
    Uses engine temperature data, received over the PCI Bus, for cold engine blower lock-out.
    Uses engine RPM data, received over the PCI Bus, for wide-open throttle A/C cut-out.
    Uses vehicle speed data, received over the PCI Bus, to determine air-flow over the condenser for optimum cooling performance.
    Uses Ambient Temperature Sensor data, received over the PCI Bus, to optimize comfort control.
    Provides an A/C request to the BCM when compressor operation is desired.
    Provides a request to the BCM when rear defogger operation is desired.

    Controls fan speed, providing 10 blower speeds in manual mode and infinite speeds in automatic mode.

    The Blower Motor Controller provides a 5.0 volt signal to the AZC Module over the Blower Motor Control circuit. The AZC Module provides a variable duty cycle ground to the 5.0 volt signal based on input from the blower switch. When the blower switch is set to LO speed, the AZC Module provides a short duty cycle (less time grounding the signal voltage). As higher blower speeds are requested, the AZC Module increases the duty cycle (more time grounding the signal voltage). When the blower switch reaches HI speed, the duty cycle increases to where the signal pattern is almost a flat line (with brief voltage spikes).

    Controls electronic door actuator operation.

    A simplified control system for operation of the mode, recirculation, and temperature control actuators provides positive positioning without the complexity of feedback from position sensors. The AZC Module knows the number of operating actuator revolutions required for full door travel as well as the number of actuator commutator pulses per revolution. Using these parameters, the AZC Module runs the actuator for the number of commutator pulses that correspond to the desired door position. To maintain accuracy, the system recalibrates itself periodically at known zero and full travel conditions.

    AZC system doors:

    Two, two-wire electronic blend door actuators.
    One, two-wire electronic mode door actuator.
    One, two-wire electronic recirculation door actuator.

    System revisons

    The 2003-2004 model year AZC Module is NOT interchangeable with 1999-2002 AZC Modules due to revised control software.

    AZC fault codes

    Fault codes are two-digit numbers that identify a circuit that is malfunctioning. The Automatic Zone Control (AZC) control module has a system self-diagnostic mode which continuously monitors various parameters during normal system operation. If a system fault is detected, a current and historical fault is recorded. When the current fault is cleared, the historical fault remains until reset (manually or automatically). Both the current and historical fault codes can be accessed through either the front panel, or over the Programmable Communications Interface (PCI) bus using a DRBIII scan tool, and the appropriate diagnostic information.

    The two different kinds of fault codes are:

    1. Current Fault Codes - Current means the fault is present right now. There are two types of current faults: input faults, and system faults.

    2. Historical Fault Codes - Historical or stored means that the fault occurred previously, but is not present right now. A majority of historical fault codes are caused by intermittent wire harness or wire harness connector problems.

    AZC self-diagnostic mode:

    1. To enter the self-diagnostic mode, depress the a/c and recirc buttons at the same time and hold. Rotate the left temperature control knob clockwise (CW) one detent.

    2. If you continue to keep the a/c and recirc buttons depressed, the AZC control module will perform a Segment Test of the Vacuum Fluorescent (VF) display. In the Segment Test you should see all of the display segments illuminate as long as both buttons are held. If a display segment fails to illuminate, the vacuum fluorescent display is faulty and the a/c heater control must be replaced.

    3. After viewing the Segment Test, release the A/C and Recirc buttons and the display will clear momentarily. If there are no fault codes, the “00” display value will remain in the VF window. Should there be 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. Record all of the fault codes, then see the Current and Historical Fault Code charts below for the descriptions.

    Clearing fault codes

    Current faults cannot be electronically cleared. Repair must be made to the system to eliminate the fault causing code. Historical fault codes can be cleared manually, or automatically. To clear a historical fault manually, depress and hold either the A/C or Recirc button for at least three seconds while the display is in the fault code mode of operation. Historical fault codes are cleared automatically when the corresponding current fault code has been cleared, and has remained cleared for 72 ignition cycles. The faults have been cleared when two horizontal bars appear in the Test Selector display.

    AZC fault codes
    Input faults 01 = IR thermister circuit open
    02 = IR thermister circuit shorted
    03 = Fan pot shorted
    04 = Fan pot open
    05 = Mode pot shorted
    06 = Mode pot open
    07 = IR sensor delta too large
    08 = Reserved
    09 = Reserved
    10 = One of four motor drivers has drive "A" shorted to ground
    11 = Engine air intake temperature bus message missing
    12 = Country code bus message missing
    System faults 13 = Mode motor not responding
    14 = AI (Recirc) motor not responding
    15 = Left temperature door not responding
    16 = Right temperature door not responding
    17 = Mode door travel range too small
    18 = Mode door travel range too large
    19 = AI (Recirc) door travel too small
    20 = AI (Recirc) door travel too large
    21 = Left temperature door travel too small
    22 = Left temperature door travel too large
    23 = Right temperature door travel too small
    24 = Right temperature door travel too large
    25 = Calibration check sum error
    26 = Engine coolant temp bus message missing
    27 = Vehicle speed bus message missing
    28 = Engine RPM bus message missing
    29 = OAT bus message missing
    30 = Display intensity bus message missing
    31 = VIN number bus message missing
    32 = Raw OAT buss message missing

    Input faults 33 = IR thermister circuit was open
    34 = IR thermister circuit was shorted
    35 = Fan pot was shorted
    36 = Fan pot was open
    37 = Mode pot was shorted
    38 = Mode pot was open
    39 = IR sensor delta was too large
    40 = Reserved
    41 = Reserved
    42 = One of four motor drivers had drive 9A9 shorted to ground
    43 = Engine air intake temperature bus message missing
    44 = Country code buss message missing

    System faults 45 = Mode motor was not responding
    46 = AI (Recirc) motor was not responding
    47 = Left temperature door was not responding
    48 = Right temperature door was not responding
    49 = Mode door travel range too small
    50 = Mode door travel range too large
    51 = AI (Recirc) door travel range too small
    52 = AI (Recirc) door travel range too large
    53 = Left temperature door travel too small
    54 = Left temperature door travel too large
    55 = Right temperature door travel too small
    56 = Right temperature door travel too large
    57 = Calibration check sum error
    58 = Engine coolant temp bus message missing
    59 = Vehicle speed bus message missing
    60 = Engine RPM bus message missing
    61 = OAT bus message missing
    62 = Display intensity bus message missing
    63 = VIN number bus message missing
    64 = Raw OAT bus message was missing
    65 = Reserved
    66 = Reserved
    67 = Reserved

    Calibrating AZC door actuators

    Calibrate the door actuators after making any repairs to the AZC system. To calibrate the door actuators proceed as follows:

    1. Turn the ignition on.
    2. Set the AZC to automatic.
    3. Turn the ignition off.
    4. Remove the IOD fuse from the Power Distribution Center. Wait several seconds, and then install the IOD fuse.
    5. Turn the ignition on. Do not touch any of the AZC controls for at least one minute to allow the calibration function to run to completion.

    Every 20 key cycles the AZC head initiates a re-calibration routine which identifies pulse counts required to achieve full door travel. Also during this routine all modes and functions are validated as functional. When the self calibration routine is complete, the control head resets itself to its last settings.

    The air conditioning compressor will engage in certain modes to cool and remove moisture from air entering the passenger compartment. The AZC control, when it is not set in the auto mode, always defaults to A/C enabled. The LED illuminates when the control requests A/C. The customer must toggle A/C off by depressing the button every time he turns to manual mode or the A/C is enabled. Additionally, when the vehicle is off for a "calibratable" amount of time, automatic A/C is again enabled and the customer must again force it off by depressing the button.


    (Under construction)

    Change in outlet temperature from desired setting - 1999-2001 models (see TSB # 2400701)

    Cold air leaking into passenger compartment foot well - 1999-2000 models (see TSB #242599)

    Condensation on exterior of heater housing - 1999-2000 models (see TSB #240699A)

    Heater A/C system changing to defrost mode when accelerating - 1999-2000 models (see TSB # 242499)

    Reduced airflow from center outlets - 1999 models (see TSB # 240799)

    Temperature coming from the HVAC system blows cold air only. - Air temperature remains cold regardless of the position of the temperature knob. Observe the temp door actuators on the HVAC housing while rotating the temp knob. If the actuators rotate, but the air temp does not change, the problem could be a broken temp door or temp door stop. Blend doors and doorstops are available through the Mopar Parts. The part number of the doorstop is 05012711AA.

    Temperature fluctuation in the automatic mode - 1999 models (see TSB #241699. Involves AZC module recalibration. Also addresses having to set the temperature too high or low to maintain a comfortable passenger compartment, constantly having to adjust the temperature setting when in automatic mode and temperature overshoot in automatic mode).

    Water drips onto the passenger floor when air conditioning is on - Ensure the condensation drain is free of restriction. High temperature and humidity will promote condensation buildup on the exterior of the HVAC housing. Self adhesive foam tape is available that will help absorb water droplets that may form on the HVAC housing. Dry the areas where water condensation is the most. Carefully install self adhesive foam tape Part # 05015245AA.

    Whistling sound from heater blower - 1999 models (see TSB # 240899)


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  10. #10
    Join Date
    Apr 2000


    I codes 52 and 56.

  11. #11
    Join Date
    Jun 2001
    Providence, RI


    Quote Originally Posted by BOMBER
    I codes 52 and 56.
    Yup; follow the blend-door writeup in the FAQ, or read the numerous complaints that will come up with a search.
    Bob Barry
    '02 Overland

  12. #12
    Join Date
    Oct 2005
    Vancouver Canada


    Yep....$831.00 later and now I have heat.....holy F-ing s--t!!!! Got the stealership to fix it on Thursday, 6 hours labour at $100/hour plus parts and tax.
    Why doesn't a lawyer get a hold of this along with the warped rotor problem ($300 in May) and give it to DC up the A$$ to make them pay a portion....the mechanic that did mine has done 15 JGC since September!!!

    Cheers all,

  13. #13
    Join Date
    Dec 1999
    Sugar Hill, Georgia


    I've got the same problem with my dual climate control, passenger side gets zero hot air, driver side is nice and toasty...

    What is it that causes it and how difficult is it to replace? Also, the blower at the passenger's feet vibrates like hell even with the knob on low...
    Jeff Baker at
    2000 Sienna Red WJ 4.7, QTII, Ltd. 4" lift (2" Daystar BB w/ 2"OME HD Springs), Bilstein 5100's (JKS: BPEs and Top shock mounts), OME SD40, ORGS adj. track bar, BFG A/T KO's (265/75/16), ORGS Rock rails, Turbocity Air intake w/ K&N cone, 3" Kolak Exhaust, 9005/9006 Silverstars.

  14. #14


    Buff here's what it says on

    A very common problem in 1999-2004 model Grand Cherokees has been weak blend and recirculation doors in the HVAC systems. The doors are turned by a motor attached to the bottom of the door at the end of a hinge shaft. The motor stops turning when there is enough physical resistance from the door stopping against its housing. This puts stress on the shaft/door junction and over time strips the shaft so that it spins almost independently of the door. The motor then experiences little resistance and keeps turning, which sends the "travel too large" code.

    In January of 2004 Jeep issued an informational TSB (#24-001-04) which introduced newly designed sub assemblies. The newly revised assemblies have stop tabs that stop the motor from turning, instead of relying on the weak shaft/door contact. It is recommended that the respective sub-assembly be installed if a blend air door(s), a recirculation door, a door link, or a sub-assembly housing requires replacement. The table below provides the part numbers for the new HVAC sub-assemblies.

    04' WJ Laredo
    Kenwood mp425 cd/mp3/wma Headunit, Kenwood SR903 Sirius Receiver,RF Punch P2002 Amp,RF Punch 10" Sub Box
    AVS In channel ventshades
    245/75-16 MTR's
    Rusty's 2" BB
    ARB Front Bumper
    PIAA 520 driving lights
    K&N 77 series FIPK
    Hypertech Power Programmer

  15. #15
    Join Date
    Dec 2004
    Fayetteville, North Carolina


    Just did a set on Saturday, one of the only three big problems with owning a WJ Rotors warping, axle noises and a dual zone ac system that craps out when the weather changes.
    The Fleet
    92 XJ Rusty's 4.5" lift with spacers and RE Boomerang shackles, Dana 30 with a Lock Right 4.56 gears, 2000 XJ front brakes, Chrysler 8.25 with 2000 XJ axle shafts and Trac Lock, ZJ rear disk brakes, 35" BF Goodrich Mud Terrains, NP 242 case, Borla Header Rusty's 2.5 inch Cat- Back exhaust with Flowmaster muffler, Products for Power High Flow 2.5 inch Cat
    03 Ram 1500 5.9L 4X4 Off Road Package(tow rig) 28570R17 BF Goodrich All Terrains, Flowmaster Dual exhaust
    05 KJ Wife's Jeep 3.7L 42RLE NP 231 Chrysler 8.25
    93 Mustang speed project
    94 XJ new project

  16. #16


    I'm now having this problem, with the pasenger side of course. I'll ask the question again, has anyone gotten creative and figured out a way to fix it without removing the dash? Or, just figured out a way to manually "patch" it (manually moving the door from ac to heat?)?
    I did a couple things to make life a little better since I don't have a grand laying around or 8+ hours of free time. I stuffed a couple socks in the passenger floor vent. I also figured out that if you don't turn the climate control to auto, and just put it on floor (or wherever you want it) and hit the recycled air button it only blows air thats the same temp as inside the jeep, and not cold ass air from outside (I may remove the sock now that I figured this out).


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