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  • Cold Aircon

    Hi there, for all of you with a 120 and think the aircon is not cold enough well it probably isnt, Not sure on the climate control models but as mine is a GXL (pre 07 so is the old dial set up, not digital) I have modified the thermistor. The problem is the thermistor is to close to the evaporator so doesnt get time to cool down properly before the compressor cuts out. Now I like cold aircon thats going to work on a 40 degree day, when I first got the prado the air was coming out the vents between 9 minumum to 11 then back to 9 and so forth, I had a bit of a play with it a while ago and got it down to just nudging 6 and back upto 7/8, its now coming out the vents at 3 and up to 5 1/2 then back down to 3 and so forth, this is the best as it wont freeze up but is going to keep the cabin nice a and cool (dont have duel aircon) It was just a matter of getting the thermistor away from the evap enough for the compressor to have time to cool the evap down to a respectable temp (3) but you also need to keep an air flow movement over the thermistor or the variation times between cutting in and cuttin out will vary to much eg you might get down to 3 but then the compressor wont cut back in till say 8, huge to much variance. A variance of about 2 or 3 degres is ideal, so for any one wanting to do it I have attached a couple of pics of what I have done if you want to give it a go. I had some plastic tubing from work, a little connector at the end where the pipe connects to evap box (this is where the original thermistor was located) dont want any kinks in the tube as you need air flow, it was just a matter of moving the thermistor upp and down the plastic tube to get the right variance in temp, the further away from the evap the lower the temp the air will come out, the closer the warmer the air. If all else fails and you cnat get it right (you should be ok) then you just put thermistor back in where you got it from and its all back to normal how it was.......Pics arnt real clear as I just quickly remembered to take them before I put it back together....
    Attached Files
    Last edited by Steve M; 11-11-2011, 03:46 PM.
    Face lift 150 Prado V6 auto. No mods yet

  • #2
    If the system is gassed and running properly it should have no
    problem cooling the car in any temperature.

    Usual cause of insufficient cooling are:

    To little gas this doesn't seem to be your problem.

    To much gas, will cause the hoses to frost.

    Insufficient air flow, mostly your case, have you checked the fan,
    checked evaporator for blockages.

    Filter etc.

    Cheers
    LeighW
    HKB Electronics, manufacturer of the Alternator Voltage Booster, Silver 2008 D4D,Lifted,Underbody protection, Alternator Voltage Booster, Tiger Z winch, Lightforce DL, Air Horns, Tanami Drawers, Drop down fridge slide, Outback cargo barriers, Rotronics dual Battery system, Polaris GPS, HF/UHF/VHF, Radio speaker combiner, Long ranger water tank, Diff breathers, Inverter, Snorkel and others

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    • #3
      Its common with the 120, the reason is the thermistor is too close to the evaporator so thermister is picking up the cold very quickly then disengaging the compressor, it cycles fine. I have checked a few other 120's and they do it to even with the climate air (mate has VX his running at 8 to 11 to warm for my liking) Its working fine now, modified it back so now I have just moved the thermistor up its bracket a tad but still getting down to 6 so that is fine. Plenty of airflow no issues there. I use to fit aircon at toyota for 4 years, camrys,corolla's, cruisers etc. I topped the system up, took about 200g to top up from when I bought it, has dye in it as well. Too much gas will cause it to cycle on and off to quickly as the high pressure switch will activate so cause its cutting in and out to quick it doesnt have time to cool, Anyway all working fine now, Im just use to aircon that comes out the vents at 2 so it freezes you like the wifes toyota does, my old 95 use to run around 5, our commodore would be at 1. Sounds trivial but I like aircon that works, and especially as I dont have dual air it takes longer to cool the cabin.........Cheers Steve
      Face lift 150 Prado V6 auto. No mods yet

      Comment


      • #4
        I have had similar issues to what Steve M has had with my air-con and have had it vac tested and re-gas by a large Perth dealership who should know all about these things.All they came up with was they found that the 'compressor was cutting in and out more than usal'.
        So I was thinking off giving this a try- http://paulpickford.com/prado/
        White 2003 V6 GXL, 4spd auto, Vapor injected LPG, Autocraft Prem Billstein 2inch lift with poly air-bags

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        • #5
          I too like really cold a/c and have noticed the compressor cycling a fair bit. Might give this a go to give the system a lift in the really hot weather. What's the best way to remove the thermistor plastic plug?
          2004 GXL V6, 5 Sp Auto

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          • #6
            Pretty much just pull the plastic holder out, DONT pull on the actual wire itself as you may damage it, its only single core wire. I didnt take any more pics from the last lot but all I did in the end was move the actual thermistor itself down the plastic bracket and used some electrical insulation tape to hold in place. I put some on the actuall green insulation itself and wrapped to plastic holder which will come out with the wire when you remove it. Dont put any over the actual bulb on the end of the black thermistor as this is what pics up the temp and if you cover it will make a huge variance of when the compressor will cut back in which you dont want, Mine now after changing it from the last post above is running steady at 6 and 7 1/2 to 8 and back down again to 6 and so forth. Still not as cold as Im used to for toyota aircon but is way better then 9 and 11, doesnt sound like much but makes a big difference on a hot day, my old 95's both ran at 5 some times just nudge 4.6 but basically round 5. As you can see in the link by Billy the plastic clip that is heated & bent to shape I didnt want to do this incase anything went wrong I could at least put back together as it was so as I said all I did was move the actual thermistor wire down the bracket a tad and taped into place..You will see when you pull it out. All I did was remove the plastic panel from under glovebox, remove the silver (maybe yours is woodgrain) plastic trim from above glovebox, just pull out gently and the clips will come with it, removed the glove box lid (think there is about 6 philliphead screws altogether to remove) and you will see the thermistor wire on the side of the evap box, you dont need to remove airbag or any thing like that, now remember this is my experiance based on the old style dial aircon, not the duel climate controlled system which is standard in the series 2 120 prados, but im presuming it would basically be the same. You will know anyway when you pull the under panels and glove box out..Not sure where your at but Im only at Penrith (Glenmore Park) if thats any where near you Id be happy to come and give you a hand.......Cheers Steve
            Face lift 150 Prado V6 auto. No mods yet

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            • #7
              VT commodore air cond was always more effecient as it has a capacity control compressor as opposed to a static speed compressor,which allowed the compressor to load/unload depending on evap coil pressures.Our 120 constantly cycles off at 4 degrees air off with fan speed on 2 and full outside air even during a 35 degree day.

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              • #8
                Yeah our VX commodore aircon was great, even on a 40d day still was like ice inside. When we first bought the commodore new I had the air checked as it wasnt cutting in and out but extremly cold was worried it was going to freeze the evap up, wasnt till I read up about it that from the VT onwards they were all the same. I definately dont get it coming out at 4 in the 120 but then some do some dont yours been the 06 model would be the same set up as mne unless you have VX, Grande with climate air then different and is put in by the factory not like GX,GXL's were still an option and was put in by the dealer, bloody joke if you ask me, should be standard on every car/4wd/truck sold in Australia......Cheers Steve
                Face lift 150 Prado V6 auto. No mods yet

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                • #9
                  Advantages of being an air cond mechanic..
                  Even helped an old auto electrician friend re-understand refrigeration principles when he had to regas a vt and couldnt understand why it kept on hunting even though it was correctly charged..

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                  • #10
                    Thanks Steve for the info. I feel confident in doing the modification as I had the glove box out and found the wire but didn't proceed as I didn't want to break anything. I think I'll run with your suggestion of moving the wire down and taping it with electrical tape instead of bending the plastic rod with heat. Any suggestions on how far to move the thermistor based on your experience?
                    2004 GXL V6, 5 Sp Auto

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                    • #11
                      i too would like to know what position you moved it to. i relocated mine to the other side of the clip section that holds the bulb and now it gets down to around 5 but has a variance of around 6 to 7 degrees ( cuts out at 5 and cuts back in at 11 to 12 )
                      very annoying when the air goes cold - warm - cold - warm - cold - warm
                      maybe the plastic frame is blocking the bulb too much to operate correctly
                      will put mine back to std until i find out more

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                      • #12
                        Hi there barcode, yep that will happen as there is no direct airflow over the thermister, I moved myn down the plastic holder to approx half way where it goes up before it straightens out again (wish I took pics now) bit hard to explain but basically where the start of the plastic holder is (where you grab hold of it to pull it out) you start off with a straight bit, then it bend upwards then it goes straight again, I moved it so the bulb part of the thermister is on the part of the holder that is bent upwards before it straightens out for the last bit. Also when I replaced the holder/plastic bit back in the hole I put it in so the plastic holder is towards the back of the evap box more so it gets it just that tad more away from the evap itself, so when reinserting it you put it in straight as normal then if you were looking at it straight on I would turn it clockwise a tad, if very very gentle with it and really feeling it, you will feel it hit the back of the avap box when you turn it, I just turned it back what felt like about a mill or 2 so its not vibrating against the box (not that you would hear it anyway just dont want nothing rubbing) I only put two raps of tape around it other wise you wont get it back through the hole. Its amazing how sensitive the thing is. just by moving a mil or two can change the temp and if not enough airflow will affect the cuting in and out of the compressor as you have found out, end up with huge variances which is so annoying, you can feel it on your face warming up again before it cuts in. I also bit a wrap of tape around the very very end tip of the thermister. I did put mine on the back part of the plastic but is obviously getting enough airflow as I only get 1 1/2 to 2 deg variance. Its a bit of a trial and error thing till you get the best spot. I dead set spent probably roughly 12 hours over a period of a coupld of days driving around with glove box out, adjusting on the side of the road. would stop and start and so on and this is the best result I got. I did get it down to 3 at one stage but then it wasnt getting the correct airflow and out of the blue would jump to 10 then back down to 3 then would settle again then play up again so thought as much as I would like 3 all the time just wasnt going to happen so got it the best I could. Sure its not as cold as 3 4 or even 5 but 6 is better then 9 or 11 which is what I was getting when I fisrt bought it..Any issues please feel free to ask me more or if close to Penrith one day drop in and we'll check it out. I really dont want to pull myn out again just for pictures. dont want to upset anything. To actually adjust it including pulling every thing apart is 1/2 hour, its getting the sweet spot thats annoying.Cheers Steve
                        Face lift 150 Prado V6 auto. No mods yet

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                        • #13
                          Here's what I discovered, not quite the same fitting - seems like Toyota changed the design to try and deal with this problem. I'm not completely happy with the performance of my A/C cycling around 7.5 C -10. Not sure where to move the thermister on this one. Any thoughts Steve?

                          The hardest part to remove is the A/C ducting boot to the floor. One way clips are a real pain. Everything else comes out fairly easily. The A/C on an old Honda I used to drive was far superior to the Prado's. So cold you couldn't have it operate for long before switching it off even on a hot day. Not sure if its the new refrigerants they have to use nowadays or a design issue.

                          2004 GXL V6, 5 Sp Auto

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                          • #14
                            Mate that is exactly the same as in my prado, all I did was move that black bit down to the straight bit going upwards if that makes sense ?? So move it back about an inch and I had it so the green protector plastic is just prior to the first bend. Where those two side clipa are so in other words I had the black bit pointing towards the air Cheers Steve
                            Face lift 150 Prado V6 auto. No mods yet

                            Comment


                            • #15
                              Must have changed it late 03 early o4 or maybe when the 5 speed auto come in which late 04 or some thing as mine is 05 yours is 04 and the picture that is with paulpickfords attachment is an 03 model ??? Dont think its the new gas as my wifes yaris runs at a constant 3, and feezes you, our 01 commodore use to run at 1 to 2 and my old wide body camry (which was the best air ever) ran at 0 to -1 coming out the vents and never froze up which amazed me how it didnt. It was an 94 model so was the same gas as current... I have had new gas added to older system and changed all the O rings and things and dont reckon it was as cold. (sisters corolla) Cheers Steve
                              Last edited by Steve M; 11-01-2012, 12:47 PM. Reason: 94 model not 04 model
                              Face lift 150 Prado V6 auto. No mods yet

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