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Jeep Grand Cherokee A/C Heating Ventilation



  • blendor,

    My brother in law is experiencing this problem in his '02 Jeep Grand Cherokee Limited as well. I lowered the glove box and located the grill or grid area and did not see the gray foam door. I am assuming that this is why his airflow is restricted, however the defrost and floor vents seem to blow just fine. My question would be if the gray door has indeed fallen down to block the air how do I remove the door in question?
  • all the air comes out through the defrosted only. how do I fix this problem?
  • I just had this problem fixed on my 2001 Grand Cherokee Laredo. I had a vacuum leak under the battery. This also fixed my cruise control that wasn't working. My mechanic charged me 85 bucks to fix it.
  • Hi Barry. My 1999 Grand Cherokee Limited I believe needs the fan relay replaced. I put a new radiator, thermostat and water pump in and it is still overheating. The dealership will charge $95 to do a diagnostic on my car to find the problem. I of course cannot afford to do that. I have read alot of posts on this problem and see in your post that the mechanic you used did it for $200 and had to order the relay from the dealer. I have looked online and have found that most of the auto parts stores carry the kit to replace it. Is this something I have to buy from the dealership? Can an average mechanic replace it or is it difficult to do? Sorry for all of the questions. Any help will be appreciated.
  • I own a 2002 Jeep GC. Recently the A/C went from cold to cool to warm. We added freon,pulled the vacuum, added more freon and it's still not cooling. The compressor is working good. This is a 4.7L V8. Please help, the temp outside is nearly 100!
  • nigbonigbo Posts: 4
    Don't forget guys the tip I posted way back in this thread - once you have your AC sorted - run the unit on air conditioning mode for at least 20 minutes a week - summer AND winter. The gas circulation lubricates the seals and keeps it sealed. If you don't do this - the seals fail and you can gas it up as often as you like - it will leak out !!

    I have never seen this advice anywhere in a car makers instruction book. I had my Grand Cherokee '99 4.7L v8 AC rebuilt by Kings Jeep dealers after it was found to have failed @ 5 years ago and have studiously kept to the rule of run the unit on air conditioning mode for at least 20 minutes a week - summer AND winter ever since - and its never needed gassing up since then and works well to this day.

    This tip i got from an air conditioning expert - so why doesn't it appear in any car book advice?
  • had a problem recently with the heater blowers ...all you could get was cold air .read on the forum that it would probably be the blend doors....... didn't bother fixing it as it was our summertime and never needed any heat inside the car..........but now the heater has started working again ,but it is always hot even when you turn the temp knob down it is way too hot ..also when i turn the a/c on it is still hot air blowing out of the heaters...
    anyone any thoughts
  • tuggajbtuggajb Posts: 646
    blend doors that is why they call them blend doors they blend cold and warm so you can have the temp that you want
    when the support shaft brakes then you have uncontrolled temps
    search blend doors on internet
  • I have a 2004 GC where the A/C blows cool (not cold) on the driver's side and almost warm on the passenger side. What's my problem, and can I fix it myself?
  • Hello. I have similar problems. At first the passenger side heat stopped working and then here recently, the driver's side heat stopped as well. The problem is probably the blend doors. This is unfortunately a problem that ALL Grand Cherokees have. :mad:
    You can find more posts on here about it or go to the Jeep forum pages and it will have info as well. I have found that I get ALOT more help on the Jeep forum pages. There is a kit you can buy off E-Bay or online for about $125.00. The only problem with that is that you have to cut a small opening under the passenger side to get to the blend doors. I haven't done it yet, but I ran a diagnostic on the problem and that is what it said the problem is. When I get the money to fix it I will get someone who knows what they are doing to do the actual work on it. It will be getting cold soon and I sure want heat this winter. I hope I was some help to you. If you need more help, let me know. I can probably find how to run the diagnostic on it again if you want to try that. Unfortunately, this is only one of SEVERAL problems I am having with my Grand Cherokee. :sick:
  • i have 2001 Jeep GC laredo what is the name of the vacuum line under the battery box. So i can order it from the JEEP dealership.
  • hello anyone,
    I have a 1998 cherokee sport 4x4, the a/c will turn on fine but some times will cut off afer a while and some times will run just fine, when it cuts off I have to turn the a/c off for a few minutes and turn it on and it will run fine again. any Ideas as to why? I would appreciate the help,
  • Hello,

    I have a 2002 JGC 6.0 2WD. 1st it only blew cold air from the driver side and middle. The passenger side only blew cool air. I then got a recharge and it didn't take at all. After that the system only blew out warm air and no cold at all. The heater works fine. I checked the motor and its working. i checked the pin for the blend doors at that is ok. The compressor kicks on. Now, air only comes out of the defroster and no other vent. I was able to remove the radio cluster and look at the middle vents. I was able to push back the door and air did come out. I just need some help in looking for what to do. I have a 3month old and it gets pretty out and don't like him to be in the car. all help is much appreciated.
  • tuggajbtuggajb Posts: 646
    sounds as if the vacuum hose under the battery has took a c**ap dont have vacuum to the control check all hoses coming off the engine
  • Hello Ckn3103:

    Congratulations on the new baby!

    The 99/04 Jeep Grand Cherokee’s HVAC system does not have vacuum lines. All moving parts are operated with electric actuator motors.

    The AC not working properly could be a number of things, from a minor leak in the lines, control module problems, to sensors in the transmission, to name a few things.

    Your symptom of “Now air only comes out of the defroster and no other vent.” sounds like you are having Mode door or mode door linkage problems.

    If you are talking about moving a door that is behind the two vent openings under the radio. Then that is a sign of a broken mode door, because the mode door should not be able to move freely unless it is broken.

    There are three mode doors.
    To replace the mode doors you need to remove the dashboard and HVAC box from the vehicle.

    Blen Dor
  • tuggajbtuggajb Posts: 646
    my factory service manual for a 2000 jeep grand Cherokee has vacuum controlled doors for defrost and vent control the blend door controls the temp that you get out of the heater the azc system uses only electrical controls

    i assume that he has the same system that my GR has where you dont have control separately pass and driver side thus the vacuum leak test vacuum line comes in on pass side just a at the bottom of the heater box should have a check valve right by the firewall inside pass compartment
  • Hi Tuggajb:

    Yes you are right, the MTC (Manual Temperature Control) systems do use a combination of actuator motors and vacuum controls.

    Only the Limited and the Overland models have the AZC (Automatic Zone Control) systems that have all actuator motors.

    Blen Dor
  • Ok. I disconnected the battery for about an hour and now the air comes through all the vents like normal. The only thing it doesn't get cool at all. The heater works fine but no cold air. Any thoughts?? Thanks
  • tuggajbtuggajb Posts: 646
    is the ac compressor turning?
    if not could be low on freon
  • Yes the compressor is kicking on.
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