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Air Conditioning isn't blowing cold. Makes weird sound in Cab. w/ video

Discussion in '1st Gen. Tacomas (1995-2004)' started by garrettnb, Sep 23, 2015.

  1. Sep 23, 2015 at 4:30 PM
    #1
    garrettnb

    garrettnb [OP] Canadian Ambassador

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    2000 Tacoma 3.4 V6

    Turn on AC, makes weird hissing sound in passenger footwell and doesn't blow cold air. The compressor is indeed working properly. Heat works properly, blows outside air if the temp selector is pointed to blue.

    At a loss here.

     
  2. Sep 23, 2015 at 4:45 PM
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    keakar

    keakar Well-Known Member

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    first thought is you are hearing air leak out of a rupture in the line or evaporator (located behind the glove box) but then if its a ruptured line, the pressure switch should not be allowing the compressor to run without Freon so that's strange.

    confirm the compressor is really turning by looking at the front clutch to see if its spinning or staying still, the pulley will always turn.

    the compressor is simply a pump so if there is a leak it builds pressure and if the leak is big enough, you will hear the stuff in the tubing leaking out just like you sometimes hear air leaking from a flat tire. a quick test if its a leak is check to see if there is any pressure in the system. there will always be a "muted" hiss sound from the evaporator as the pressure is reduced causing the cooling effect but its barely noticeable so I don't think that is what you are hearing.
     
  3. Sep 23, 2015 at 4:47 PM
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    garrettnb

    garrettnb [OP] Canadian Ambassador

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    I understand the clutch mechanism at the pulley, the clutch is engaging properly. How would I go about checking the pressure?
     
  4. Sep 23, 2015 at 4:47 PM
    #4
    rzgkane

    rzgkane Well-Known Member

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    4Runner Trail wheels and Toyo Open Country ATII tires 265-70-17. Cosmetic stuff like Pro grille and OffRoad black bumper trim, vinyl delete on side, added hood graphic, OEM tube steps.
    Educated guess. Expansion valve. Easy replacement. Remove evap core and you are done. Denso part is $25 all over the place. Just replaced one, and the evap core on my kid's 2000. It would be cheaper to replace the valve than take it to a shop for a pressure test.

    Also, if the compressor is engaging, you haven't lost enough R-134 for the low pressure switch to interrupt the circuit, and that noise is sooo loud that you would certainly have lost all refrigerant if it was indeed a leak.
     
  5. Sep 23, 2015 at 4:49 PM
    #5
    TashcomerTexas

    TashcomerTexas My truck is a whiner

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    My a/c blew hot air all year till I replaced the whole compressor and clutch assembly, problem fixed.
     
  6. Sep 23, 2015 at 5:04 PM
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    keakar

    keakar Well-Known Member

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    ok well if its indeed running then its safe to assume the system has pressure but just go to the auto store and buy one of these http://www.ebay.com/itm/NEW-AUTO-CAR-HOME-AIR-CONDITION-AC-A-C-RECHARGING-HOSE-KIT-WITH-GAUGE-AND-BRASS/171836323088?_trksid=p2045573.c100033.m2042&_trkparms=aid=111001&algo=REC.SEED&ao=1&asc=20131017132637&meid=f80b7875c7e64500822dde49d7ce39ca&pid=100033&rk=2&rkt=4&sd=161823472981 to see what the low side pressure is doing, that's usually enough to tell whats going on or if you need to bring it to a professional to look at it.

    personally I think its better to spend a little more and buy this http://www.ebay.com/itm/R134a-Air-C...ase-/161823472981?hash=item25ad6e3d55&vxp=mtr because its going to let you see whats happening on both sides of the system and its a better value especially if you add Freon to your own vehicles. those small hoses with the gauge are pretty cheap but they work.

    you can throw parts at it and you might get lucky but you need to check the pressures and see if its the valves in the compressor have gone bad (which is pretty rare to happen) or if it is the expansion valve.

    if you want to roll the dice and just change the expansion valve and receiver drier, they cost about $25 each plus your Freon and you will need to find a vacuum pump to pull a vacuum on the system after replacing them. do that and im confident you have a 90% chance of solving the problem.
     
    Last edited: Sep 23, 2015
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  7. Sep 24, 2015 at 12:37 PM
    #7
    garrettnb

    garrettnb [OP] Canadian Ambassador

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    Before I start throwing money at it, I'm having a tough time deciphering the FSM and part catalogue drawings. Is there a vacuum line that controls something behind the dash for the AC. I realized that is EXACTLY what it sounds like.
     
  8. Sep 24, 2015 at 1:37 PM
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    keakar

    keakar Well-Known Member

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    I am not sure about 00 trucks but I suppose it is possible there is a vacuum line to the heater valve instead of a cable.

    with a/c running go under hood and feel the large aluminum line coming out of the firewall, it should be ice cold and if it is then the a/c should be working fine and maybe your problem is that the the heater is on with the a/c.

    the small line is supposed to be hot or very warm liquid line.

    I think its worth bypassing the heater core just to eliminate the possibility of heater running
     
  9. Sep 26, 2015 at 12:57 AM
    #9
    garrettnb

    garrettnb [OP] Canadian Ambassador

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    So after some research I ended up taking the truck in to a reputable AC shop in the area. If a recharge did not solve it then the cost to diagnose the problem was included in the recharge. Turns out that it has 0.2 lbs of refrigerant in the system instead of 1.6. So there was enough pressure to keep the pressure switch happy, but not enough coolant to keep the expansion valve happy, this is what was causing the sound.
     
  10. Sep 27, 2015 at 9:40 AM
    #10
    keakar

    keakar Well-Known Member

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    glad you got it all sorted out now :thumbsup:

    trying to diagnose a sound is near impossible if your not there in person to hear it.

    wish you had followed my advice to feel the tubing with it running and you would have noticed its was just a little cool instead of being ice cold. at that point I could have confirmed it was low on Freon for you.

    it still sounds odd it wasn't at least cooling a "little" if it had enough Freon to run but I suspect it was not running all the time and may have been "cycling" off most of the time.
     
  11. Sep 27, 2015 at 10:32 AM
    #11
    garrettnb

    garrettnb [OP] Canadian Ambassador

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    Oh, I actually did feel up the tubing and one may have been slightly below ambient but it was hard to tell. I was kind of on a time crunch so I needed it fixed asap. For that was Friday I took it in, and tomorrow I'm driving to Nevada from Canada. And you know us Canucks... don't like the heat.
     

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