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Jeep Grand Cherokee A/C Heating Ventilation



  • goguengoguen Posts: 1
    If your blower fan relay which is derectly behind blower fan is not in place and secured properly you will have cold air blowing in from air box.
  • ubc64ubc64 Posts: 1
    I have an 1999 JGC with dual climate control. The problem I have is when I turn up the thermostat for some heat, I only get heat on the passenger side. I only get cold air on the driver side. I replaced the heater control unit with one from the junk yard and have the same problem. I can't believe that both switches have the same problem. A dealership I called said that it might be the blend door and that I would have to pull the dash out to fix that. Has anybody else had the same problem? Also, how hard is it for the backyard mechanic to pull the dash and replace the blend door? I'm unemployed and can not afford to take it to a dealer. Any info would be greatly appreciated. Thank You.
  • tuggajbtuggajb Posts: 646
    look on ebay for Blend door repair has a repair kit that you do through the glove box hole
  • Is there a way to check a blower motor resistor on a 1997 jeep grand cherokee? I have checked the switch in dash, blower motor works when you hook up a ground wire and there seems to be power to resistor ( but it is below 12 volts) everyone thinks it's the resistor , but no one is for sure. The part costs about $70.00 and hate to buy it if that is not the problem. Before the fan stopped working completely sometimes it would not come on right away, it would come on after a few minutes. Any ideas? thanks
  • That's weird i have the same problem with my 97 Cherokee. I wish I had an answer for you but I don't,sorry. What I did for right now is I hooked up a on off toggle switch to the ground side of the blower motor. I know that it's not the proper way to repair the problem but i need to get back and forth to work. Hopefully someone can help us out with this problem.
  • I had my AC replaced in 2000 Jeep Grand Cher. While the dash was apart, had heater core replaced. I now have not heat. Heat worked fine before core was replaced. Any ideas?
  • First thing check your fuses, second check the connector to your blower motor. (real easy to forget to connect) third check the connector to your blower motor resistor. My big question is did you do the work or did you pay for it?
  • I paid to have it completed and have taken it back twice. I get the impression they don't want to spend the time to troubleshoot and have to pull the dash apart again. Good heat from hoses just very little inside - luke warm at best.
  • If the blower runs then there is a good chance they didn't get the blend doors hooked up right. Yea pulling the dash apart is no fun but you can skip a few steps in the manual and get the same results. Since you paid for the job and are not satisfied and the system doesn't work properly the shop should be held accountable, DOG EM OUT
  • Hello Mark243:

    Before dogging the repair guy.

    You should have an idea of what is wrong with your system.
    It might not be the repair guy’s fault.
    Coincidence does happen!
    It could be a faulty actuator motor, etc.

    If you have the dual control heating system, then the first thing you should do is read your fault codes.
    You can also check a few problems manually.

    The fault code system is an excellent place to start the diagnosing process.

    IF 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 what I think the problem is.

    Merry Christmas
  • Thanks for the offer but it does not have a dual control system. The mechanic who put in the heater core can't find a problem and said he may not be able to ever get acceptable heat back. I just don't feel comfortable with his ability after saying that knowing it worked fine before he took the dash apart.

    The center vents seem to blow a normal amount of air but the side vents are very weak.
  • gregvsgregvs Posts: 1
    Thanks for the info- I did this and had error codes 54 and 56. Any idea what that means?
  • I gotta problem with my 02 Grand Cherokee - the heating does not work. Up until yesterday it worked on the passenger side, a bit. But now it only blows cold air. All the vents work etc and the temp gauges but no hot air. Anybody any ideas?? I've been told I need to see a auto electrician but as its christmas I'm scratching round for money so a DIY fix is required.

    Thanks in advance for any suggestions
  • It sounds like you might have a problem with your blend doors, whether it be in the linkage or the actuator. Its not a quick fix. Be prepared to take the dash out!
  • Hey you replied to my problem about the heater fan in my 1997 jeep. just to let you know i replaced the blower motor resistor and it still doesn't work! any luck on your end? please let me know , My wife is pissed!!
  • Yo Heywood, I am still trying to figure out this heater problem my self. The problem is that I can't seem to come up with a wiring diagram for my jeep on line. I ran into an old friend of mine over new years that has access to wiring diagrams. All that I need to do is get to his shop to get a diagram. I will keep you informed once I figure out this problem. I got as far as figuring out that the problem is on the ground side of the system. I couldn't go any further without a wiring diagram. What I did find is that if I disconnected the ground wire from the heater blower motor and went straight to ground, (with the black wire that comes out of the BLOWER MOTOR) the blower will motor worked!!! So what i did was run the ground wire from the blower motor to a toggle switch under the dash so i at least have heat. The heater works only on high speed and only on defrost, but you can adjust the hot/cold switch. If you decide to try it let me know if it worked for you. At least you would have heat for know.
  • I would like to know more about the codes from the AZC system because my fan works intermittently......on various speeds as well as high. Usually it blows for about 3 to 5 minutes then stops. I can jiggle the wiring under the dash that connects to the resistor and get it going again. This leads me to believe that my resistor is working but my fan motor is worn out. My symptoms are that the wiring harness keeps melting (replaced harness once already) where the red wire connects to the plug that plugs into the resistor. I'm assuming the fan is drawing too much current and melting the wire/plug/connector.

    How do I test the voltage my fan is drawing?
    How do I determine whether the fan motor or resistor is what's bad?

    I will try the method above for getting codes first thing in the morning and reply ASAP. Any ideas or suggestions would be greatly appreciated.
  • tbeckitbecki Posts: 1
    If you are from NP you need to reply to this message.
  • Checked the doors on my '00 JGC - seem to be opening and closing. One heater hose is red hot, the other is luke warm. This is a new heater core. Can it be blocked? Any ideas?
  • My 00 GC does not have any heat, the heat works for about a second or two then it just blows cold air. The check valve, heater hoses and therm are all good what else could it be?
  • try fliping your hoses
  • Tried that. Installed water pump, thermastat, flushed heater core and did a lot of praying. I now get heat once engine gets up to temp and then goes cold as I drive it. So...had carbon test done on radiator gases. It seems like there may be a slight head gasket leak. Hard to say but when I run engine with cap off radiator, there is a very small bubble every now and then. So my only guess is a small other symptoms of a head gasket leak though.
  • if you find some thing out please let me know i have the same problem email me
  • steverstever Posts: 52,683
    If you "watch" this discussion, then you can set your preferences to receive an email alert whenever something new is posted. And your email address won't get harvested by the spammers.

    Sending info around by email doesn't help anyone else and defeats the purpose of having a forum, so please don't ask for "private" help via email. Thanks.
  • imykimyk Posts: 1
    I have no heat coming out off passenger side just cold air. Driver side is fine. Also the seat heater doesn't work on the driver side.
  • cminchcminch Posts: 2
    hi, it seems i need to replace the blend doors on my g cherokee, would anyone know where i can get instructions on removing the dash??
    many thanks
  • I've just had these problems myself.
    the following link is brilliant although it is designed towards their product for fixing the problems. the videos show how to remove the dash.
    the ac and heating problems are caused by the blend doors which there are 2 on climate models.
    these problems are caused by a design fault. the spindles which the blend doors and circ doors are connected to have plastic pegs to limit their movement and because the system self calibrates in ignition cycles and learns the limits by where the motors stop.
    after a period of time the self calibration tests break the plastic peg and the stresses are transferred to the connection between the spindle and the door which eventually breaks completely.
    if it is the drivers side which has the problem this can be accessed through the glove box.
    i have managed to repair mine by drilling the spindle and inserting a 3mm metal pin and then with a small amount of epoxy on the end of the spindal reinserting it into the blend door. this will only work if most of the blend door end piece is intact.
    for the passenger side blend door and problems with the recirc door the unit has to come out.
  • se_jonse_jon Posts: 1
    I had this problem (actually several) myself and wanted to share what I did to fix. First I had the cold air on passenger side, eventually both driver and passenger. I bought the heatertreater kit ($120) and it went pretty easy and actually worked. The next problem I discovered was "no air flow". It was the broken recirc door. I couldn't really find any good ideas without removing the dash which is way too much for my skil level. It was apparent that the recirc door had broken and fallen over the fan blocking airflow. From the glove compartment, on the right side (opposite from where the blend door repair was), you'll see a rounding in the plastic housing. Above that is the outside air intake (mesh) into the passender compartment. Using the same roto tool that was used in the blend door repair, I removed the mesh and extended the opening downward so that I could get my hand in. Then I removed the broken door and covered the entire opening with aluminum covered tape purchased at a HVAC supply store. Airflow restored and the entire heating system works for $120! (two months now-really cold here in NJ) I need to point that I no longer have dual controls and no longer have use of the outside air recirculate function, but the heat works-relatively easy repair. I have some pictures but I cant figure out how to insert them here."> Hope this helps some cold friends out there. My regards
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  • Update.....I bought a wiring kit sold by jeep dealers specifically to repair the wiring harness connector that plugs into the blower motor resistor. All went well for a while and within a few weeks the plastic connector was melting again. Since the fan functions at all various speeds and not just on high I'm guessing the reistor is ok but the fan itself must be drawing too much current. I decided to inspect the fan as it was suggested that leaves, etc. may have fallen in there creating extra resistance. I removed the fan and it was clean so I decided to remove it to see if I could find anything wrong with it. Seemed to check out out ok but I noticed when I spun it by hand it would only complete 2 1/2 revolutions. I also noticed a brown dirty dust or more like rust powder falling out of the motor vents. Given the number of miles and age I figured the fan motor must be wering out. Looked at a new one and when I spun the fan it would itself only complete about 3 revolutions. Wondered if it was my problem after all but decided while I had everying apart I'd go ahead and put in a new fan. After replacing the fan all seems to be good. Knock on wood, it's going on 2 weeks now and the wiring harness connector isn't getting hot.

    I also found references for my codes and was told it's more than likey that my blend doors are going to crap out soon.
  • I have no heat in my cab, I thought the heater core was plugged so I back flushed the core with the heater on, coolant and air came out the supply side. indicating it was clear. I hooked everything back up and and once again I have hot coolant going to the core and no hot coolant coming out of the return side to the engine. Can anybody help with this problem. Does anyone know if there is a valve anywhere thru the heater core system?
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