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Toyota Sienna Heating / Cooling



  • jijubarjijubar Posts: 1
    I too have a similar problem. The compressor clutch does not always engage when AC is turned on but when it does, everything works great. Where exactly is the cabin temp sensor and if open, can it be substituted with a resistor of appropriate value to indicate the need for cold air?
  • 19791979 Posts: 2
    We have a 04 Senna with about 56000 miles on it. When the engine is on it sounds like water running in the air conditioning heating unit. Does anybody have any ideas? The dealer says he can hear it but will need the car at least a day and will have to contact tech support.
  • wwestwwest Posts: 10,706
    There is ALWAYS water/coolant running through the heater core within the A/C plenum but you should never hear it unless the coolant level is low enough to be moving air bubbles.

    Be sure your coolant level is proper.
  • pit1pit1 Posts: 7
    :( :cry: We have 20004 Senna with 25,0000 miles. Last week the rear ac stopped blowing cold air. The front is working ok. I open the rear compartment where the rear blower is located and feels like there is plenty of cold air inside the blower. Its just not getting to the rear vents. Can anyone help/ thanks
  • brintegrabrintegra Posts: 2
    hi there!

    did u get this problem sorted out - was it the resistor or fuse / i have a sienna with 10K miles with the exact problem.

    would appreciate any inputs - my email is

  • jzx81jzx81 Posts: 3
    It turned out to be the A/C Heater Relay, PN 90080-87025, $16.40 from dealer. Luckily, we have a guy at the dealership (bought the Sienna from him) that hooked us up with free service even though warranty was over.
  • 19791979 Posts: 2
    Didn't get it fixed. Dealer wanted $1100 To replace the ac panel and wasn't sure that would fix it. We just live with it doesn't do it all the time.
  • relooky01relooky01 Posts: 6
    I also have a 2005 Sienna. On several occasions the blower and AC would not come on when the blower switch is in any of the ON positions. They did eventually come on and worked properly the rest of the day. I suspect the HTR relay (Toyota PN 90080-87025) is working intermittently and have a new one on order ($18.18 from the local Toyota dealer). It is located in the fuse box under the hood next to the battery. I switched this relay with the RR A/C relay next to it and then the rear heater/AC blower would not come on but the front blower worked fine.
  • khardingkharding Posts: 5
    I am having the exact same problem with my heater/cooling fan switch. I start up the car, try to turn on the A/C or Heater, and nothing works. I then drive for about 5-10 minutes, with the setting on low and it may kick on. I try to turn the A/C to a higher setting and it goes off. Did replacing the HTR relay ultimately fix the issue? $18.18 is a little more palatable than replacing the switch, and easier also...
  • relooky01relooky01 Posts: 6
    I replaced the HTR relay on Saturday and so far the blower is working fine. Once the blower came on I did not have a problem with the A/C going off at a higher speed setting as you mentioned. Once it came on it worked just fine at all speeds. By the way, I was able to remove the cover from the old relay by prying it over the 4 tabs. I connected the relay to a 12 volt power supply and measured the resistance across the closed contacts (the two large terminals on the relay). The resistance varied each time I energized the relay. I then polished the contacts with some real fine crocus cloth followed by a strip of heavy paper (from a business card). The resistance across the contacts was essentially zero after that with the relay energized and the relay worked fine. Although I did not try it back in the car I have every reason to believe it would work as good as new. As a suggestion, try swapping the HTR and the RR A/C relays (they are located next to each other) and see if the intermittent problem moves to the rear heater blower. Good luck!
  • We have the same problem in our '06 Sienna. We brought it to the dealership, but they couldn't figure out what was wrong - we should have checked this forum first. How do you remove the HTR relay? If you just pull hard enough, will the relay pop off? Do you need to pry the relay off with a tool? Do you remove the blue cover? Thanks.
  • khardingkharding Posts: 5
    To remove the HTR relay, you open up the fuse box under the hood near the driver's side, pop off the fuse box cover and then find the appropriate relay. On my '05, the schematic is on the under side of the fuse box cover. You should just pull the relay straight out like a fuse. I would avoid using a tool if at all possible so as not to break anything unless there is a special relay puller tool. The relay is in there tight, but with minimal wiggling, it should pop straight out. These relays cost about $18-20. I just switched out the RR A/C with the HTR relay and now we are dealing with the intermittent issue in the rear air. I will pick up another when convenient, but at least I know that this was the problem. I do not think the blue cover on the relay itself is removable. Good luck
  • xavyxavy Posts: 2
    Just purchased used 05 Sienna (50K) two months ago, wife noticed odorless vapor/smoke blowing out of center dash vent today. Has anyone ever encounter this before? What is the cause? Dealer wants us to bring in because they say they have never seen or heard of this issue.
    Are they just blowing smoke?
  • xavyxavy Posts: 2
    I purchased an OEM key today, and had locksmith cut key, no problem.
    Went to program myself, followed instruction, did not work. Any suggestions other than paying dealer $89.00 an hour for a 2 min. job? Thieves is the common word for them.
  • wwestwwest Posts: 10,706

    Humid day, A/C cools the air to dewpoint, you get FOG flowing out of the vents. Usually only lasts until the A/C is able to fully cool the evaporator down.
  • marty08marty08 Posts: 3
    I bought the Sienna in the Fall and when Winter came, we noticed that it takes over 20 minutes to get any considerable heat from the vents. If you let the vehicle in "Park", warming it up, it takes over 25 minutes to get any heat. When you drive it, within a minute of start-up, it is usually 20 minutes or 7 miles, before you get any heat. I've taken it into the dealership, under warranty and they stick the radiator and say it's OK. I tried to make them keep it overnight and start it in the morning, when it's cold and they claim that if it's at the correct operating temperature when they check it, it won't make a difference. I tried to explain that perhaps the thermostat is not closing all the way and the dealership stated that they have never heard of this. Has anyone else had this problem? I have a 97 4-Runner and a 90 Toyota Pick-up and both warm up within a few minutes and even the temperature guage goes to normal, just warming it up without driving it. :confuse:
  • wwestwwest Posts: 10,706
    Does the engine coolant temperature guage come up to the correct level in the normal time and yet there is no heat..??

    Or does the engine coolant not come up to temperature..??
  • mfc3mfc3 Posts: 8
    I have 2005 Sienna with only 10K miles. Now I press AC on/off switch and nothing happens. The AC switch light is always off. The air blows do work but they are just sucking air from outside. Does anyone know what is going on ? Where should I look for ? The car warranty just expired.
  • I had a similar issue with the switch in the on position, no A/C light, and no fan was functioning. I switched out the A/C relay in the fuse box and that seemed to fix it. I have not dealt with a fan that is working but A/C not working. Sorry.
  • mfc3mfc3 Posts: 8
    Thanks, kharding. I will go back to check if the fan is actually working. I did recall the rear AC fan is woring. Do they(rear and front AC) share the same relay ?
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