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Jeep Grand Cherokee A/C Heating Ventilation

371 messages,  Last post on Oct 27, 2009 at 2:04 PM

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What is this discussion about? Jeep Grand Cherokee, Heating / Cooling, SUV


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#316 of 371
2003 Grand Cheorekee with A/C and Heat problems by matthewbowes86
Apr 21, 2009 (11:29 am)
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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.
#320 of 371
2003 Grand Cheorekee with A/C and Heat problem [matthewbowes86] by heatertreater
Apr 22, 2009 (7:39 pm)
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Replying to: matthewbowes86 (Apr 21, 2009 11:29 am)

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
#321 of 371
Re: 2003 Grand Cheorekee with A/C and Heat problems [matthewbowes86] by blendor
Apr 23, 2009 (6:21 am)
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Replying to: matthewbowes86 (Apr 21, 2009 11:29 am)

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
#322 of 371
Jeep Grand Cherokee Heater AC by heatertreater
Apr 24, 2009 (3:05 pm)
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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
#323 of 371
Re: Jeep Grand Cherokee Heater AC [heatertreater] by matthewbowes86
Apr 24, 2009 (5:24 pm)
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Replying to: heatertreater (Apr 24, 2009 3:05 pm)

Thanks for the advice. I did the fault code process and got 52, 54 and 56.
#324 of 371
Re: Jeep Grand Cherokee Heater AC [heatertreater] by matthewbowes86
Apr 24, 2009 (5:26 pm)
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Replying to: heatertreater (Apr 24, 2009 3:05 pm)

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.
#325 of 371
Grand Cherokee Heater Repair by heatertreater
Apr 24, 2009 (10:54 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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