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Hissing noise when accelerating then dies out

Discussion in 'Stock 2006 -2010 Explorers' started by 16EBBOY, January 9, 2011.

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    1. 16EBBOY

      16EBBOY Member

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      I have a 2006 Explorer Eddie Bauer V6 and sometimes when the heat is on and at the beggining of my acceleration, it will hiss for about 5 seconds then stop but will do this everytime i accelerate. This only happens occasionally. To elaborate on the sound, it sounds like when you turn the manual climate control from on to off and then it sounds like the air is being released. Any ideas?
       
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    3. waskly

      waskly Well-Known Member

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      i would say normal, you can change parts, but if its a little his on accel from the passenger side foot well, its something that just exists in every 4th gen ex alive.

      my 2010 did this with 12 miles on it when i picked it up, i sorta giggled but its how the engine vacuum is lost.

      and just a characteristic of the vehicles.
       
    4. bender

      bender Active Member

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      it is common as mentioned, however if yours exhibits the following it is more than just a characteristic. Many of us have the same noise but it also coincides with the HVAC going from panel to defrost on it's own (under extended periods of acceleration such as up a grade). mine's been in for it a couple of times over the past year with 2 repairs and no improvement. it is not an issue 100% of the time, but keep an eye on that symptom. otherwise, year there isnt any harm or danger.
       
    5. extrememon

      extrememon New Member

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      I fixed it!!!

      The issue with this is the hose on the pink colored T-Connector that is connected to an air pump. Over time, the hose gets stretched out and there is a gap between the rubber material of hose and the air pump connection. The hissing sound from accelerating is derived from the air pressure within the vacuum (not sure of exact details that go on within the vacuum). Anyways, fixing this all you need is electric tape, scissors, and 5 minutes.
      1) Follow the sound of the hiss and you'll see the pink T Connector I am talking about. if you're not sure if that's the right hose, turn the air console to off and then back on (you'll hear the lovely hiss coming from it).
      2) Remove the T Connector from the air pump.
      3) With electric tape, you want to make the hose that connects to the pump smaller since it has stretched out. Constrict the hose with a reinforcement of the tape; the goal in mind to decrease the circumfrence of the hose (Do not make it too small so that it can't go back on the pump).
      4) Connect it back in place and you should be good. You may not get it right the 1st time out, but play around and you'll fix the most annoying problem I have ever dealt with.

      FYI---I took my car into the dealership to have this problem fixed. All I got was a $104 diagnostic charge (refunded since I told them how I fixed it myself) and they told me everything was fine.
      Hope this helps.
       
    6. waskly

      waskly Well-Known Member

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      air pump?

      no explorer to date has an air pump.....
       
    7. extrememon

      extrememon New Member

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      I'm not a technical car person. I guess it's not an air pump... I think what's more important is that it solves the hissing problem; please don't get stuck on my car part ignorance.
       
    8. bender

      bender Active Member

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      where is the part located? under the passenger side dash or in the engine bay. please be more specific.
       
    9. extrememon

      extrememon New Member

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      It's under the side dash. No need to pop the hood.
      Basically if you sat in the passenger seat and extended your feet all the way towards the front of car as far you can, your toes would be pointing towards it. You're going to have to lie on your back to get in there enough to see it, but you should be able to tell exactly where it is while you're down there by switching your air from Off to On to produce a hiss. Once you located the sound, you should see a black circular part with a pink T shaped hose coming from the back of it (you might need a flashlight). This is the part you want pull out and operate on by tie a tight layer of electric tap around to reduce the diameter going into the "black object."
      Hope this helps, if not please let me know and I'll attempt to provide further details.
       
    10. waskly

      waskly Well-Known Member

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      i find it hard to believe a car that is 2 months old from the factory to delivery to 12 miles on the odo has stretched lines. or actually not working properly.

      considering i have seen 1000's of ex's do this, and less its at idle, with no accel its normal to the car.

      the noise you hear is the change in engine vacuum coming off idle.

      you can change every part, with out actually hindering how the climate control work, you will not actually get rid of this noise, it always comes back.
       
    11. bender

      bender Active Member

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      waskly- mine (and some others) the hiss coincides with the airflow going from the vents to the defrost position by itself, this is not 'normal operation' that is a defect.

      the quick hiss followed by what sounds like a valve shutting may be normal, but with mine the hiss draws out until enough vacuum is lost that the airflow defaults to defrost.
       
    12. waskly

      waskly Well-Known Member

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      it is normal, if under load, going up an incline. if the load is big enough then the engine will not make engine vacuum to supply to the accessories.

      if you were to put the controls on floor only, then pull the source line to the bottle, it will default to defroster, this is the default setting when no vacuum is present.

      the bottle under the dash will last a whopping 10seconds if that.
       
    13. extrememon

      extrememon New Member

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      The initial issue from 16EBBOY sounded exactly like the problem I had with the short lived hissing upon acceleration. Before anything else, did you give my advise a try?
       
    14. Freddconr

      Freddconr New Member

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      Extrememon can you please give us more details please as I am having the same issue.
       
    15. extrememon

      extrememon New Member

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      Sure...
      Have you located the exact tubing that I referenced above? You can locate it by having a friend stick his head under the glove compartment and you can turn the Air Control from ON to the OFF (facing up) direction (that's when the hiss kicks in). Or if that doesn't work, have someone listen when the air is on and you turn your car off.
      Once you locate the tube that connects into a black oval shaped object, feel around to familiarize yourself to what you're going to be working with (it's very hard to see). Essentially the tube is the female part, while the oval shape object has the male.
      To put it in terms any guy would understand, the tube (the female) has gotten a bit loose and she's stretched, so the seal on the male piece is not air tight anymore. You want to make her a virgin again :)
      Remove the tube. Use electric tape and near the top of the tube, wrap it around tight so that the diameter of the tube is smaller; thus making it a tighter fit on the male part. This should eliminate the air gap, and the on-going hiss that made me insane for a good few months.
      Good luck and please let me know if this helps and/or if you need me to try a different way to instruct; but I think you should get the general gist.
       
    16. Mrmielnichuk

      Mrmielnichuk New Member

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      2007 explorer xlt. I have found that the hissing noise coming from under the right side dash is air going back into the little oval tank, the tank and connection were actually fine, what caused my problem is the one way check valve under the hood, just underneath the comp. module is the two lines comin out the firewall from inside, the one that turns and goes towards the back of the engine has a one way check valve that is quitting, allowing air to go back into the car, the hissing is the air going back into the tank, 9 dollar part and 20 seconds to change it. I think this is why people have the problem continuing, pull the valve out and vacuum test it, ( or blow through it ) air should only go one way, replace it and make sure the black side faces the engine.
       
    17. Snakehn

      Snakehn Member

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      I actually like the little hiss, sounds like is turbo charged or something lol
       
    18. Old As Dirt

      Old As Dirt Active Member

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      I had this problem with my 2007 XLT (manual heating and cooling) and found the grey line under the hood (there is only a black and a grey line coming through the firewall) was disconnected at the valve near the alternator. It only misbehaved when the temperature was set to the blue (cool) setting as this line controls a heater hose shut off valve. The vacuum in this grey line apparently only activates when in the cooling mode so you wouldn't hear it in cold weather.
       
    19. polizi212

      polizi212 Active Member

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      Do you have the Part number that you replaced???
       
    20. baddriver

      baddriver Member

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      [​IMG]

      here is the check valve
       
    21. snakester

      snakester New Member

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      Mine has developed this problem as well. This thread was looking promising but died without pinpointing a solution. If anyone was able to fix this a detail of the process would be much appreciated. THX
       
    22. Flag Gibby

      Flag Gibby Well-Known Member

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      It seems that the OP was referencing the lines going to the vacuum reservoir and others indicate it to be the check valve under the hood.
       
    23. snakester

      snakester New Member

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    24. sync58

      sync58 New Member

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      It definitely was a problem with the A/C Check Valve. I had a broken vacuum reservoir so the A/C took a while before turning on with the damaged part, once I changed it the dreaded noise came back! I replaced both parts and the hiss went away... thank you guys!!

      Here are some instructions with some pictures
      http://imgur.com/a/2guSo
       

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