AC temp difference - Recirculation vs Fresh-Air

Discussion in 'KJ General Discussion' started by whitejeep05, Aug 16, 2017.

  1. whitejeep05

    whitejeep05 Full Access Member

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    I've run into something interesting with my AC system. I'm troubleshooting a possible problem with my condenser, and came across an interesting difference in air recirculation modes. (My AC struggles to cool the cabin when it's been sitting in the sun.)

    There's a huge difference in temperature:

    Recirculation mode - 45deg F
    Fresh-air mode - 59deg+ F

    It seems like the air isn't circulating through the evaporator, or my condenser really can't cool down ambient air due to humidity?
     
  2. teeje

    teeje Full Access Member

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    How's the charge? Recirculation mode is going to be different. Humidity has a lot to do with it as well. Also, recirculation will be cooler because the compressor is cooking off hot air that's already been cooled down where as it's cooking hit, humid air from the outside and in turn makes the compressor work harder. Either way, check the charge. Hookup a pressure gauge too

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  3. whitejeep05

    whitejeep05 Full Access Member

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    Thanks, I will check the charge, and i'm going to borrow the pressure gauge from my local auto parts store. The fresh air mode is basically unusable since it blows through at 60+ deg and never cools the cabin.

    Also, hoping someone might be able to answer this for me, how hard is the air flow from your blower motor? I cleared the inlet screen behind the glove box a while back and it improved it, but still doesn't seem to blow as hard as maybe it should.

    Thanks
     
  4. Rowlette

    Rowlette Full Access Member

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    Fresh air will always be harder to cool the cabin because it is mixing the outside air/ engine heat with the cabin. It not too difficult to realize "Fresh" means mixing while recirculate mean a close loop system.

    Laughing at Oneself and with Others is Good for the Soul[emoji16]
     
  5. Myke

    Myke Full Access Member

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    Just throwing in another "this is how mine is too"
     
  6. whitejeep05

    whitejeep05 Full Access Member

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    Thanks, yes, I was aware that it would be less efficient than recirculation based on what I read in the manual but the temperature difference was pretty significant... i thought something might be malfunctioning. thanks for all the input.
     
  7. HoosierJeeper

    HoosierJeeper Gold Supporter/Admin Staff Member Administrator

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    On mine the fresh air mode is plenty cold....recirc is a bit colder and blows a bit harder but either one will freeze you out. Fresh air mode shouldn't be much warmer.

    Check the metal screen behind the glove box....it gets clogged up.
     
    Last edited: Aug 16, 2017
  8. teeje

    teeje Full Access Member

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    Check the cabin air filter below the windshield cowl

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  9. whitejeep05

    whitejeep05 Full Access Member

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    Well, I expected the fresh air to at least be cool, but this isn't. I thought something might be malfunctioning, but not exactly sure how to diagnose it. I've cleared the plastic screen behind the glovebox, i'm going to be cleaning the condenser tomorrow morning and will report back if that changes anything.
     
  10. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    Here is some FSM info:
    [​IMG]
    The Jeep doesn't have the coldest ac on the block, especially when you are stuck in traffic at idle.
    I throw mine into park sometimes and keep the rpm above 1000 to stay cool and my ac is all within specs as above temp guide.
     
  11. HoosierJeeper

    HoosierJeeper Gold Supporter/Admin Staff Member Administrator

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    Let us know how that goes! Hope that works.

    If the condenser was plugged up, I don't think it would cool at all. I'm not sure. I'm wondering if you have a blend door issue. There's a reset procedure somewhere on here.
     
  12. whitejeep05

    whitejeep05 Full Access Member

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    There was some improvement after cleaning the condenser fins with coil cleaner. I'm about ~40deg on recirculation, and in the 50s for fresh air mode which is slightly better. I live in a hot/humid part of the country, so the poor performance in fresh air mode might be expected.

    I am going to leave my car out in the sun tomorrow and see how it does with the cabin extremely hot which was my primary problem... took entirely too long to cool down when it sat in the sun.
     
  13. tjkj2002

    tjkj2002 Full Access Member

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    If you tested this right after spraying the condenser it would throw off the numbers since the condenser is still wet.

    Plus testing air duct temps while not moving is not the best indicator of performance.A good indicator that the system is operating correctly is measuring the temp drop from ambient temp to center vent temp.A 30-40 degree drop is a perfectly working automotive AC system.
     
  14. Aztimer2

    Aztimer2 Full Access Member

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    It's blazing hot here in Phx,Az so I just leave my A/C in recirculated position. I have to lower the window to let the hot air out. LoL it gets hot here. Now they say window tint will help.


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  15. nnote

    nnote Member

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    Same here. Air is good in the morn or eve, but midday, just doesn't cut it. And my whole A/C system is brand new, the WHOLE system. I kinda miss my ol Suzuki XL-7 that had the passenger vents in the back
     
  16. LibertyTC

    LibertyTC Well-Known Member Staff Member Moderator

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    Ya recirculated offers the coldest output. Shade is your friend wherever possible.
    Luckily my Jeep came with the factory dark tint for the rear section.
    I use one of those reflective front windshield pads to keep it much cooler inside too.
    [​IMG]
    We are not allowed to dark tint the front side windows here unfortunately.
     
  17. uss2defiant

    uss2defiant Full Access Member

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    AZ ppl need to tint as much as you can.

    Got to use a good AC compressor as well.
     
  18. whitejeep05

    whitejeep05 Full Access Member

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    I used to live in Phoenix, and this definitely wouldn't cut it there. I am now in Austin and the humidity really kills efficiency out here.

    I tested temperature outputs in different conditions and I feel it's as good as it's going to get. Going to just have to use a windshield reflector and shade as you all suggested.
     
  19. nnote

    nnote Member

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  20. rjkj2005

    rjkj2005 Full Access Member

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    There is no filter but there is a metal screen.

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