Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Toyota Sienna Heating / Cooling



  • The engine fans are running faster than they normally do an they only do this when the engine reaches a higher rpm. It also makes a vibrating noise when they run faster.
  • Anyone know about this.....

    I have an 04 sienna that when the HEAT is turned on it blows cold air(AC?) on the right side vents , and hot on the left side.

    Bizarre, just started this out of nowhere?
  • fibber2fibber2 Mid Hudson Valley, NYPosts: 3,732
    There is an air mix box in the center of the dash behind the middle vents that contains both the heater core and the AC evaporator. CE & LE models have one temperature air mix solenoid & flap, while the XLE has two (separate left and right controllers & a more upscale split mixer box. The hardware and controls are different, so which van are we talking about?
  • in My car AC or Heat turns on only when car is running on 40 miles or more speed.
    As soon as car stops at traffic light or it is in park position heat or Ac does not work. while in park position cooling fan runs rapidly and makes noise.
    I added coolant in radiator. Heat indicator in Auto meter panel after car runs few miles remains on slightly higher then middle position.
  • mhw1mhw1 Posts: 1
    I have a 2009 Sienna and we noticed last night that the middle and rear vents were blowing cold air while the front vents were blowing hot air. We let it run for 15-20 minutes, tried turning it on and off and everything else we could think of. Does anyone know what is wrong.
  • Have a diagnostic run on the rear heat/ac. Something (a sensor) might be telling the system that it is hot in the rear so it is not letting the hot air circulate. The diagnostic read out will tell you what the system thinks the temperature is in the rear, this governs the systems response.
  • joeskjoesk Posts: 1
    Hi, my 2006 Sienna does not blow air out of the front vents for both heater and AC(rear fan works fine) I can turn on heater or AC for the rear seats but would not blow air in front. is there a fuse for front heater/ac blower fan? Thanks, Joe
  • Check post number 132 on page 14. Swapping the two relays should move the problem from the front to the back if the front relay (HTR) is bad. Worked on my 2005. Good luck.
  • arprincearprince Posts: 3
    Having issues with the aircon unit for sometime. It does not cool (heater was ok during winter). I would add freon and it would be cool (but not as good as before when it was working fine) for a few days. Have done so (add freon) several times already. Any possible remedies I can check? TIA
  • fibber2fibber2 Mid Hudson Valley, NYPosts: 3,732
    Clearly, you have a leak somewhere that needs to be properly diagnosed and fixed! Either get the stuff with the florescent dye and get a blacklight, or take it to a shop that has a electronic leak detector.
  • jaredl_jaredl_ Posts: 1
    I have this same problem in my 04 sienna. wondering if you ever found a solution?
  • I have a 04 Toyota Sienna LE AWD and had the ac stop working. It had been working fine the day before and even earlier in the day, but now it just blows hot. I doubted it was the problem but to make sure bought some refrigerant to add to the system and it almost seemed like the low pressure side was not low pressure as none of the refrigerant would go in. But maybe it was just that it didn't need any at all. What should I do to test and find/confirm the problem?
  • b1tbuck3tb1tbuck3t Posts: 1
    edited July 2012
    We have a 2001 Toyota Sienna XLE which is having A/C problems. Intermittently it is not blowing cold air in the front. The rear A/C is able to consistently blow cold air. Checking the inspection port on the drier shows bubbles moving when the compressor kicks in. I would not be surprised if it could use a little refrigerant given the age of the vehicle but the system is blowing consistently cold air in the rear.

    When the A/C seemed to stop working we have found if you raise the temperature in the front to max heat and then adjust it back down to cool it seems to get stuck on heating. Conversely if you go to max cool you can usually get it to switch to cool even when raising back to 74 degrees.

    There is a ticking noise directly behind the center vents (where I assume the mixer box is) that will stop if you go to max heat or cold but seems to continue if you leave it at around 74 degrees.

    Any help with additional trouble shooting steps would be appreciated.
  • fibber2fibber2 Mid Hudson Valley, NYPosts: 3,732
    edited July 2012
    A constant ticking sounds like a failure of the air mix solenoid assembly. A solenoid is a motor with positional feedback, so the clicking is likely from stripped gears as a result of the motor trying to fight a stuck blend door.

    Edit: Sorry - got side tracked and didn't finish the thought.... So, you'll need to work up from under the dash to locate the solenoid, and replace it. But as important, check out the mix door movement to ensure it moves easily. Binding or lack of lubrication will only kill another motor assembly.
  • traveling back from florida trip with 50 degree oat
    we had trouble getting heat to driver's side unless set to
    "max heat". seems intermittent at best.
    due for first service, do I have legit complaint? thread seems to
    point to repeating problem
  • prowl66prowl66 Posts: 2
    How have things gone since you did this?. I have passengers side blowing cold but driver's side blowing warm. This sounds great if it works but doesn't cause other issues
  • gsblossgsbloss Posts: 1
    at about the same time these two things started to happen, not sure if they are connected...Fan Speed Switch for Heater/AC only turns the fan onto high when in the high spot, no other spots make the fan work. Same week the car over heated while parked with the engine on and AC on. Only took 10 min and his done it twice.
    Coolant levels are fine and no leaks have been found
    But when my wife got home yesterday, while the car was warm I noticed the left side (drivers side) cooling fan on the radiator was not turning, but when I turned on the AC it would still not come on, BUT as soon as I turned the fan speed switch to off the fan would come on for a brief second and then turn off not to come back on. Any ideas?
  • fibber2fibber2 Mid Hudson Valley, NYPosts: 3,732
    edited July 2013
    There is a fan control logic module behind the radiator between the fans on a post (IIRC). That gets temperature data, plus settings info from the AC Amplifier (dash control panel) and outputs to the fans. While it could be a bad fan motor, most likely one of these electronic units isn't telling the fans they need to be running.

    The dash gauge on most cars is really dumbed down, and the needle will hang in about the same spot when the engine is from around 170-215' F. You need to be plugged into the OBD port to really see what the coolant temp is. So likely the temps are climbing, but you don't get a real indication that things are going bad until just before the coolant boils at 235' F.

    The interior fan speed switch also interfaces with the AC Amp, so perhaps it's pointing to that module as well. It's going to take some professional diagnostics to figure this out. The blower motor speed control also relies on a blower resistor module that is located within the interior air stream to keep it cool. I once had an overheating engine that blew such hot air into the interior that it cooked this module and melted the solder on the individual resistors! The result is a single high speed, and the open ckts at the other spots will be off - exactly as you described. So perhaps the events are connected. After addressing the overheating, I (being cheap) simply resoldered the resistors back in place and the module lasted the life of the car.
Sign In or Register to comment.