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Toyota Highlander Heating Ventilation and Air Conditioning

24

Comments

  • djmetakdjmetak Member Posts: 1
    I had the same problem with airconditiong on my 2005 Highlander. When I would select either heat or cold, it would be changing on its own every couple of secs. And then I found this forum and read some of your comments. I took off the temp knob, and there was a little screw which I just tightened and now it works like it should. Before I found these forums I was thinking of taking the car to the dealer who would probably rip me off. Thank you guys a lot.

    Since you helped me fix this problem, maybe you can this one also.

    Couple of weeks ago somebody broke into my car. They broke the drivers window. I ordered a brand new window from the Toyota dealer and raplaced it myself. The window works fine up and down, closes, opens but the only problem is the "Auto up". When I pull the which all the way up for the window to automaticly close, it come all the way up, and then by itself opens (comes down) half way and stays like that. In order for me to close it without opening on its own, I have to close the window manualy, not pulling the swich all the way up for the "auto close". I was told that I need to reset the motor and for that the dealer wants 150 bucks. I just don't think that it is worth that much money and that there is a another way to solve this problem. Does anybody know how I can reset this window so my Auto works?

    THank you in advance...
  • wwestwwest Member Posts: 10,706
    Try "normalizing" the window by holding the switch in the up position for about 20 seconds after the window is fully up.
  • AnthonyVWSmithAnthonyVWSmith Member Posts: 2
    Highlander 01 with the Auto Climate controls. Recently had the engine replaced and the AC works fine except when I put on the recirculation button. If the weather is cold and I turn on the recirculation button, it remains on... but when the weather is warm it seems to reach a certain point and then the recirculations starts to turn itself off and on, off and on. Any ideas
  • karen42karen42 Member Posts: 2
    my '04 Highlander A/C started blowing warm air. A check at my repair shop showed no freon so they added some and checked for leaks. Had cool A/C about 24 hrs, then hot air again. Freon added again but no leak ever found and again had cool air for about a day. The condenser and clutch are fine so I was told the evap core is probably the problem Also, when I just have the vent control on and the temp know turned too the cool side, hot air will come out when I go around a curve or corner. Very weird. Any ideas? I was told replacing evap core was very labor intensive therefore big $$. I live in an area where I need the A/C in the warm months. Thanks for any help/suggestions.
  • mikefm58mikefm58 Member Posts: 2,882
    I had a wierd similar problem like you described, but I wasn't low on freon. The air temp. in my case would also go between hot and cold by itself. Grab a hold of the temp. control knob and shake it. It should be firm. If it's loose, pull it straight out and check the nut that tightens down on the bolt. Tighten it down and use some lock tite so it won't come loose again.

    Good luck and let us know if this fixes it.
  • wwestwwest Member Posts: 10,706
    Many automatic systems will turn the system to fresh airflow within a few minutes if the A/C is not operating. Otherwise too much danger of moisture buildup in the cabin and the soon thereafter windshield fogging over.
  • howza1howza1 Member Posts: 1
    You Rock!

    Just fixed my Highlander in two minutes by tighening the nut.

    Car was blowing hot air even in the off position, and only hot with the AC on.

    Now it works like new.

    Thank You!!!!!
  • mikefm58mikefm58 Member Posts: 2,882
    Cool, glad I could help, I've even heard from others that had taken their vehicle to their dealer and been given huge estimates to replace major components of their A/C or heater systems. I've got to believe there is a TSB from Toyota somewhere.
  • AnthonyVWSmithAnthonyVWSmith Member Posts: 2
    Have now resolved the issue and it turns out to be TOO MUCH freon which causes the pressure sensor to cut out. I'm guessing that the garage I used filled the freon manually and put too much in. So if you have the situation where you can get cooling when the re-circulator is switched off, but when you put on the re-circulator the A/C continally switches on and off, then check the freon levels.
  • tidestertidester Member Posts: 10,059
    it turns out to be TOO MUCH freon

    I didn't know that was possible. Thanks for the info.

    tidester, host
    SUVs and Smart Shopper
  • wwestwwest Member Posts: 10,706
    Too much refrigerant and the pressure switch that activates the compressor is always open, especially if the OAT is HIGH.
  • jannersjanners Member Posts: 1
    It is definitely the nut behind the control knob. i believe htis is a fault with Highlanders. It comes loose and finally the wires break behind the knob making the heat either full on or intermitent.
    I tried to solder the wires but in the end bought a replacement unit on ebay for $200. the dealer wanted $700 to do it and $565 just for the part. it is easy just pry out the facia and then undo 4 screws the whole thing pops out and then replace with new or used unit.
    If you are good at soldering it could save you a lot of money. If it has only just happened you may be lucky and get away with tightening the nut behind the control knob

    Good luck!
  • karen42karen42 Member Posts: 2
    I took the temp control knob off and the nut was loose just like you all said,so I tightened it. It helped with the cool/warm air blowing when I just used the vent,. but my A/C still blows warm air when I turn it on. I'm afraid I'm going to have to find a repair shop to check it out. I will not go to the dealer since I don't really trust them not to rip me off. Thanks for all the suggestions.
  • ojnucciojnucci Member Posts: 3
    Hello,

    Could you tell me which part it was you bought on ebay? I would like to do the same thing- my Highlander has been doing this for about 2 years so I've been just half-turning the temp control knob to get cold (though it has still been very intermittent!). Its been a huge thorn and I've been quoted from two separate shops at over a grand to replace the "Blender Box."

    THanks!
  • ggartnerggartner Member Posts: 3
    Janners: the "Blender Box" is probably what I bought. It has been a while, but I took the module that the knobs hooked into to a junk yard. They found the replacement part - the first one they found, did not work when I installed. They searched other locations around the state and found another one. The second one worked like a champ. I think I paid about $125 for the part finally.
    Sorry this is not more help.
    Gary
  • ojnucciojnucci Member Posts: 3
    This helps a lot actually. I have just started the online junk yard scavenging today. However, after tightening the bolt behind the temp control knob it works much better--so I may give it a few months!
    Thanks Gary.
  • kburger1kburger1 Member Posts: 2
    thanks for pointing me to the loose nut behind the temperature control knob. as thanks here is further info. If you tighten the nut and it still doesnt work try taking the nut off completely and gently move the knob to different positions with the blower on max air. If it changes from hot to cold in different positions the 3 wires connecting that control switch to the next upstream board are severed (broken solder joints) you can remove the whole assembly with the radio first disconnect the positive terminal of the battery. the trim around the radio and ac controls just pulls straight out from the bottom and then at the top very easy. disconnect the wires they are keyed, large connectors goto the air controls, small connectors to the radio. you need to resolder the wires back onto the control knob board. I have been soldering along time and it was hard. good idea to test joints with a multimeter. if you short any of them it probably wont work. you will show continuity between wires even when its done correctly, 2 have full continuity and you also have 1 with a resistance of like .7 which i think is an inline resistor. i replaced the existing grey flate wire with 3 small guage individual wires. label it so you dont get any wires crossed. I just got done test driving the car and the ac and heat work perfect. I hope this helps people out there to fix these problems without paying thousand of dollars to the dealer. I just fixed mine for free. Very satisfying.
  • rutrut Member Posts: 5
    In my 2002 highlander the air temp will vary with the slightest of bumps. It will jump from hot to cold immediately.

    The dealership wants $800 to replace the panel:( I'm thinking it is a loose wire or something.

    Anyone else seen this problem?

    Rut
  • mikefm58mikefm58 Member Posts: 2,882
    Start reading posts backwards. Your answer is in there.
  • wwestwwest Member Posts: 10,706
    "...slightest of bumps.."

    Most likely a loose/intermittent connection to the OAT, Outside Air Temperature, sensor mounted behind or on the back of the front bumper just forward of the AC condensor/radiator stack.

    And open connection will indicate a sub-freezing OAT and the AC compressor will be disabled and the system will go into heating mode as long as the sensor is open.

    Another "bump", connection closes, AC cooling returns.
  • slowcarslowcar Member Posts: 66
    Problem description: in a hot day, the aircond only blows out cold air in the passenger side vents, warm air still in the driver side vents. The aircond was put in the recirculation mode; never have from the outside. My thought was that there was some thing (a valve, maybe?) blocking the cold air from going to driver side.

    What's wrong?

    Solutions?

    Thanks all for help.
  • leean21leean21 Member Posts: 1
    ok, let me try this again, without hitting the enter button before i put a message....anyways, I just recently started having the problem of hot air blowing through while my ac is on, then switching back to cold air....i have tightened the nut behind the temp switch and am hoping that is the fix....thanks so much for all the information...you guys are awesome
    ;)
  • rutrut Member Posts: 5
    I actually took it apart and found a broken wire connecting the temp knob to the ckt board. It was a 3 wire cable soldered on each end. I removed the cable and replaced it with 3 individual wires. Problem solved.
  • jorge6088jorge6088 Member Posts: 3
    I have same problem and tightened the knob. This has reduce problems but once in a while still get switch from cool to heat. How do I fix the broken cables? are there any specific instructions on how to do this?
  • jorge6088jorge6088 Member Posts: 3
    I have same problem and tightening knot did not fix it. I like to try to solder wires. Could you please send me more specific instructions on how to remove ac unit? thanks.
  • rutrut Member Posts: 5
    You have to remove the complete unit out. it just kinda snaps out if I remember correctly. there is a circuit board that you have to remove. There are a few screws holding it in. Be careful handling the board as to not emit any static electricity that would take out the ic's on the board.

    You will find a small circuit board mounted where the temp control is. Go assuming you have taken the knobs off in front and removed the nuts on the controls, you can unclip the board and pull it out. There is a 3 wire cable connecting the circuit board to the temp switch. Mine had a broken wire at the small board. Be very careful trying to solder this back. It requires a small tip and not too much heat.

    Hope this helps. Better than spending $800 for a new one or $300 for a used one.

    Rut
  • alirobalirob Member Posts: 17
    Slowcar, I have exactly the same problem on my 02 Highlander. Have you found a solution yet?
    Rob
  • slowcarslowcar Member Posts: 66
    No...It seems like you and I were the only ones having this problem. It must be some thing very simple that prevents the freon from going to the driver side's vent. Hate to bring it in the dealer and spend $thousands$ .... Please post it here if you found some thing. Thanks.
  • rohoorohoo Member Posts: 2
    slowcar,
    I have the exact same problem on my 01' Highlander. The temperature range is approximately 12-18 degrees warmer on the drivers side as opposed to the passenger side. I will let you know if I come up with anything.
  • cps2698cps2698 Member Posts: 3
    Just wanted to thank the original poster regarding the ac temp issue and the loose nut. Just as you said, my husband took the knob off and the nut was loose. Boy am I glad I was reading this yesterday. It saved us a lot of money!
  • slowcarslowcar Member Posts: 66
    Any news? Also I noticed that the driver's side air will kick in cold if the outside temperature is low enough, like in the low 80's. I even heard a "click" sound from a solenoid when it started getting cold. Of course the passenger's side stays cold the whole time.....Any body's having an idea? Please help.
  • wwestwwest Member Posts: 10,706
    Thiis is just/simply a guess. In the conditions you describe the Toyota and Lexus series automatic climate control has always, since at least 1990, been VERY prone to sudden, inadvertent, fogging of the interior windshield surface. There is even addressed, obliquely, within your owners manual with a direction to NEVER have the system in defrost/defog/demist mode during cooling airflow operation.

    While those systems are prone to "automatically" putting the system into a mode wherein the danger is more likely to arise, having the manual system in recirculate mode during cooling use is one of the base criteria for "stumbling" across the same windshield fogging situation.

    Even without the system being in defrost/defog/demist mode there is still a not insignificant possibility that the windshield interior surface will be cooled to the cabin dewpoint and gradually, or in some unique case, SUDDENLY fog over with a light coating of condensation.

    What you may be experiencing is Toyota/Lexus latest FIX for the HAZARDS arising from a seriously flawed A/C design. Having the driver's side air outflow be somewhat higher in temperature would undoubtedly allviate some of the potential for windshield fogging on that side of the vehicle.
  • kricket2kricket2 Member Posts: 1
    yes, my heat does not stay on "hot" The dealer says it is vacuumed sealed
    and it needs to be replaced for $1000.00. you can pull the knob off and adjust
    the nut. however I have hit bumps in the road and it turns to cold air. I called
    Toyota and they will not recall it due to it is not a "saftey problem" It is when I
    am unable to defrost my windsheild. I am not paying that... more calls to Toyota
    to help them recall this issue.
  • slowcarslowcar Member Posts: 66
    Thanks, wwest for the information but I don't think that was the problem. The air cond had been working just fine all these years and the problem just popped up more than a year ago. I don't think the temp in driver side is higher than that of the passenger side...it's just that the driver side vent sucks in the carbin's air (recirculation mode) and blows it right back out without having the liquid freon going thru the evaporator. When I heard a little "click" sound of the solenoid then the driver side started getting cold just like the other side. Anyway, thanks for the info. If you can think of any thing else, please advise.
  • wwestwwest Member Posts: 10,706
    The mechanical airflow path of automotive A/C.

    Air inlet with a damper door to select fresh intake airflow or recirculate. Fresh airflow is usually taken in at the foot of the windshield on the passenger side (US). Recirculate airflow is taken in from an opening behind the glove box' traditional position. ALL system airflow, regardless of fresh/recirc intake origin, then flows through the pollen filter, the blower ("sucker") and then to, through, the cooling evaporator core. The cooling evaporator core is typically operated at ~34F(***). So if the blower speed is fairly low the airflow temperature at this point might be very close to freezing.

    The next step is the reheat/remix vane/door. The control system will "set" the position of the vane door such that a selected portion of that just previously cooled airflow will be diverted from the "main" flow path and through the ~180F heater core. Downstream of the heater core the two airflow portions will remix/merge and the end result will be system outlet airflow that is cool enough, sometimes just BARELY cool enough, to maintain the passenger cabin, OVERALL, at your selected temperature setpoint.

    If you turn the manual control to maximum cooling or the automatic one to the lowest temperature setting then NO airflow will be reheated and the outflow might be discomfortingly COLD.

    *** Currently no method is used to moderate the operating temperature of the evaporator, mostly in order to take full (but RANDOM) advantage of the evaporator's dehumidification aspects.
  • slowcarslowcar Member Posts: 66
    wwest: few questions.

    1) It doesn't seem to be efficient to heat up part of the cold air (+34F) with the +180F heater core and then re-mix it with the original cold air to regulate the temperature. It's like running your house aircond at full speed and then open the windows slightly to maintain the set temperture.

    p.s. BTW, I thought the car air cond regulates the temperature via the Expansion Valve, where it opens to allow liquid freon from the Condenser to flow to the Evaporator if it wants to cool down the air. When the cabin's air is cool enough this Expansion Valve will be closed; thus no more cooling. Am I wrong?

    2) Is there a vane door separately for passenger side and driver side so that on the driver side, the vane door was stuck and won't allow the cold air to go through and mix in with the warm air? If there isn't a separate vane door for the driver side, then why the passenger side's temp is much lower (20F) than that of driver side if both sides share the same vane door?

    The kicker is that the system had been working no problem until recently !!! So it can't be the problem with the Toyota aircond design.
  • ryan99ryan99 Member Posts: 46
    Whoever found this quick fix is a genius! I've had my Highlander for three weeks and today found the heat to be erratic. I took the knob off and sure enough the switch was loose and I could duplicate the problem in my hands...Thanks again!
  • davidc4607davidc4607 Member Posts: 4
    I am having the same problem with my 2004 highlander. The temp setting is stuck on 75 degrees. I have pulled out the circuit board and the 3 wire cable connecting the circuit board to the temp switch is not broken. I think I will have to replace the circuit board; however, I have not been able to locate one. Does anyone have any other suggestions as to what might be wrong & how I can correct the problem?
  • wwestwwest Member Posts: 10,706
    1. Yes, HORRIBLY inefficient these days when public focus is, should be, on FE. But you don't get the full benefits of dehumidification on a humid summer day unless the A/C evaporator operates at the lowest possible temperature.

    All I know, or think I know, is that the temperature of the evaporator vane surface area is not easily moderated. So we get downstream "moderation" via the remix/reheat vane/door setting.

    2. These days, even if you did not purchase a climate control with the L/R different temperature settings the "core" system may still have that capability for purposes of parts commonalty. Then the question becomes is the function being used..? It would make sense to if the radiation sensor indicates the solar radiation heating effects are primarily on the passenger's side then more cooling would/might be routed to that side. A L/R system malfunction is also a possibility.

    To extend FE I often run my climate control systems on MAX COOLING and recirculate. Then I use the blower speed to regulate the overall cabin temperature. If that still results in too much cooling to my face and upper body I set the outlet airflow to dash/footwell combined or footwell only.

    That being said....

    Climate control systems designed by Denso US, NipponDenso, have shown an unusual propensity for sudden spontaneous fogging of the interior surface of the windshield. So running the driver's side outlet airflow a bit higher than the passenger side might well be something of a corrective measure to help alleviate these instances.
  • davidc4607davidc4607 Member Posts: 4
    Anyone have any answers to my question above?
  • bobincobobinco Member Posts: 2
    Probably a straight forward one for you all. I have a 2009 HH - I doubt that it being a hybrid affects this issue. I have the manual heating and air configuration. It's annoying that even with the fan turned to the off position and cabin recirc disabled, I get some mixed air out of where ever the selection knob is pointed. Of course, you can get no air flow in the recirc mode but when the humidity gets high enough in the cabin it automatically goes back to outside air and the air starts coming through again. Is it designed like this - outside mixed air when not in recirc- or is mine broken with a vane that's not closing all the way? We never noticed this in our test drives because it was august and 100f and the A/C was on continuously
  • wwestwwest Member Posts: 10,706
    First, you probably do not want absolutely no incoming fresh airflow for the same reasons the system will not remain in recirc with the A/C off. The best you can do is place the system in defrost/defog/demist mode and therefore "baffle" the incoming airflow. If you want minimum heating of the incoming airflow then simply place the system in max cold and defrost/defog/demist mode before tuning it off.
  • bobincobobinco Member Posts: 2
    Thanks for the answer but I must admit I'm a bit baffled by it. The downside of not providing fresh air to the cabin - off really means off - is not apparent to me. Instantaneous fogging of the front window can't be an issue if there is no airflow to get the moisture there. I guess they're trying to protect you against yourself in the event that moisture levels really build up and you turn on defrost/demist. I gather from your answer that the system is designed this way and that mine is operating as designed. I like my Highlander immensly but "the draft" is driving my wife, and therefore me, nuts
  • wwestwwest Member Posts: 10,706
    Human body metabolism, breathing & perpiration, is a high source of moisture in a closed passenger cabin, 4 passengers = DANGER.

    During the winter months the incoming fresh airflow will typically have a lower Rh than the cabin atmosphere. Have you tried routing the incoming airflow to the footwell. Also, during automatic operation the footwell airflow is often as much as 20F warmer than the airflow you get from the dash outlets.

    Oh, and you can, and should, manually close the leftmost and rightmost dash airflow outlets.
  • tidestertidester Member Posts: 10,059
    Oh, and you can, and should, manually close the leftmost and rightmost dash airflow outlets.

    Aren't those the ones that are intended to remove moisture from the side windows?

    tidester, host
    SUVs and Smart Shopper
  • wwestwwest Member Posts: 10,706
    Yes, but primarily only if the A/C is operating. Poster is complaining of the discomfort from natural throughput airflow due to forward motion and these vents can ONLY be closed manually.

    Besides which, I have NEVER expereinced the front side windows being a problem. IMMHO it is ALWAYS the windshield that initially fogs over, begin sto fog over.

    The airflow from any dash outlets can be discomforting during cool or cold weatehr operation so I always try to remember to close these during the wintertime.
  • tidestertidester Member Posts: 10,059
    I have NEVER expereinced the front side windows being a problem.

    My side windows invariably become a problem when fogging occurs. Fortunately, I live in a dry climate so it doesn't happen very often.

    tidester, host
    SUVs and Smart Shopper
  • wwestwwest Member Posts: 10,706
    Do you mean in addition to windshield fogging..??

    If not then the airflow from the side vents themselves may be the problem, carrying moist airflow due to the A/C being cycled off as a result of declining OAT or even "exiting" the defrost/defog/demist mode with the A/C otherwise disabled.

    Any time the A/C cycles off there will always be a substantial level of condensate remaining on the ~10,000 square inches of evaporator vane surface area. The only place for that to "go" is to (slowly..?) evaporate into the passenger cabin. Might even be, often is, the next morning before you see the results of yesterday's A/C operation.
  • tidestertidester Member Posts: 10,059
    Do you mean in addition to windshield fogging..??

    Yes. It was a major problem when we lived back east in a much wetter climate.

    tidester, host
    SUVs and Smart Shopper
  • wwestwwest Member Posts: 10,706
    Was not only a PITA but downright dangerous here on the "wet" side until I figured out how to "manage" the climate control system. Basically I NEVER allow the A/C to operate for other than actual cooling. Using the c-best options it remains fully off, "disabled" throughout the winter months.
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