Jeep Wrangler AC/Heat Problems

paperv2paperv2 Member Posts: 2
My air conditioner/heat only works when it's on high. It doesn't work on any of the other settings. I'd like to fix this myself, can anyone help me with this.


  • mac24mac24 Member Posts: 3,910
    The lower speeds of the blower are controlled by a resistor pack which can be found in the passenger foorwell area of the hVAC housing.

    It's likely that this has burned out and needs replacing.
    Other less likely causes are a bad control switch, or issues with the wiring and connectors.
  • paperv2paperv2 Member Posts: 2
    I changed the blower motor resistor today. It worked great for about 3 minutes, and then shut off. The blower motor resistor was very hot to touch. Do you think that the part may have been defective, or is there a wiring issue?
  • mac24mac24 Member Posts: 3,910
    The resistor pack is designed to get hot. It works by using some of the power going to the blower motor thus slowing it down, and in doing so the resistor gets hot.

    As the blower runs without blowing any fuses on 'high' it would appear to be ok.
    You need to check the switch, wiring and connectors on the lower speed circuits. Check the appropriate fuses too.
  • wink53wink53 Member Posts: 2
    When I turn on my a/c or heater, no matter what position the selector is in, it comes out of the windshield defroster. It turns off when the selector is in the off position so I know the knob isn't set up wrong. Also, every once in a while, it comes out of the defroster and the floor vents at the same time.
  • mac24mac24 Member Posts: 3,910
    As you chose not to post the year of your Wrangler I can only give the generic reply.
    The issue is with the diverter doors in the HVAC housing, which depending on the year may be manually controlled, or more likely operated by vacuum actuators.
    If vacuum operated then the problem could either be a vacuum leak, faulty actuator(s), or a bad control switch (which controls both vacuum and electrics).
    It's also possible that the doors are physically damaged, which was quite common on some years as the doors and linkages were made from a very brittle plastic.
  • wink53wink53 Member Posts: 2
    My apologies. My Jeep is a 2002
  • mac24mac24 Member Posts: 3,910
    edited August 2011
    My apologies. My Jeep is a 2002

    Vacuum controlled in that case.

    You can see the actuators move if you get your head into the footwells while someone operates the control knob.

    If all the actuators work then the problem is damage to the doors or linkage inside the HVAC housing. Fairly big job to dismantle.

    If some of the actuators work, then either some have failed or there's a problem with their vacuum feeds. Fairly easy to trace.

    If none of them work, it's likely to be a major vacuum leak. Simple, start at the inlet manifold and follow the hoses until you find the leak.
  • hikerguy64hikerguy64 Member Posts: 1
    97 Jeep Wrangler Sport.

    When selecting floor level vents for heat, I notice only a little air coming out of the floor vents, with some air exiting at the defrost and demisters as well. Does not noticeably change when fan speed is increased. If panel or defrost vents are are selected there is noticeable strong air flow.

    Does this sound like a floor door or actuator problem or is this normal operation.

    Just had the upper fan box replaced to repair the bad mixing door. Dealer is now saying this air flow pattern is normal. I certainly does not feel normal when more air exits high when the floor vents are selected.
  • mac24mac24 Member Posts: 3,910
    The airflow at floor level is usually perceived as less powerful that that at face or screen level.
    The vents are small compared to those on the dash, and unlike your face and hands, your feet and legs are usually covered.

    However, if only the floor vents are selected then there should be little to no air coming from the face and screen vents.

    With a little contortion you can watch the actuators move the doors as you operate the sliders on the HVAC control panel.

    If an actuator functions but the door doesn't move, check the linkage between the two.
    If the actuator doesn't function, look first for a vacuum leak.
  • tjjeep1tjjeep1 Member Posts: 1
    My top vents blow cold air, but my bottom vents blow warm/hot air.
  • mlw7mlw7 Member Posts: 2
    The ac/heater will stop blowing then will come back on. The blower motor and the resistor / module has been replaced...did not fix the problem.
  • hump79hump79 Member Posts: 1
    I have a 2002 Wrangler TJ and am experiencing a like problem. A/C will come on and blow cold air, but at higher acceleration, the air stops coming out of the vents. As I slow down, or maintain speed at a lower speed, the air cold air will start coming out of the vents again. I can still hear the blower motor cranking it out at full speed, but the air isn't coming out. I have replaced the vacuum lines going to the module, as I was thinking this was the issue. Are there other vacuum lines I should be checking? I really don't want to have to rip out the dash unless it's absolutely necessary and am hoping that it's just a vacuum loss, since the acceleration of the vehicle seems to be having a bearing on the air output. Any help would be greatly appreciated...this is TX and it's HOT!!!
  • marybethmcgmarybethmcg Member Posts: 6
    I am looking at purchasing a 2012 Wrangler Unlimited and in the vehical history it came up that on two occasions the air/heater compressor needed to be replaced. It was repaired under the warranty but just wondering if this is common and nothing to worry about or a sign to steer clear of purchasing.

    Would appreciate professional opinion/advice.
  • bootdraggerbootdragger Member Posts: 1
    I have exactly the same problem, hump79. The A/C fails to blow air out of the vents upon acceleration but blowing is restored at lower speeds. And this occurs even when the vents are blowing ambient air, so I don't believe it is a freon issue.

    Did you ever find a solution to your issue?

    Thanks - Tom
  • mlw7mlw7 Member Posts: 2
    I never did find a solution for my problem. I called the dealership back and told them that they did not fix the problem when i took my jeep in for repairs. What I was told is that they do not know what the problem is and to wait to see if any more problems occur. Hopefully my jeep will still be under warranty when/if I do have any more problems.

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