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SUVs Jeep Cherokee and Jeep Grand Cherokee Jeep Grand Cherokee A/C Heating Ventilation
372 messages, Last post on Oct 27, 2009 at 2:04 PM
You are in the Jeep Cherokee and Jeep Grand Cherokee Forum. Your Hosts are steve_ & tidester
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Replying to: matthewbowes86 (Apr 21, 2009 11:29 am) 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 |
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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
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Replying to: heatertreater (Apr 24, 2009 3:05 pm)
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Replying to: heatertreater (Apr 24, 2009 3:05 pm) |
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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
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Replying to: heatertreater (Apr 24, 2009 10:54 pm)
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Replying to: matthewbowes86 (Apr 27, 2009 2:02 pm) HeaterTreater |
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Replying to: matthewbowes86 (Apr 24, 2009 5:24 pm) 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 |
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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
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