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Toyota Avalon Climate Control Questions



  • I have a 1998 Avalon with the same problem described in message #83. The HVAC will run OK for weeks and then all of a sudden it stops working. Sometimes I can turn the engine off for a few minutes and when I restart the engine the system will start working again. I've taken it to my local dealershipp and they say that they're not aware of a service bulletin for this. They said thier diagnosis was to relpace the computer (which I did for about $650) and it seemed to fix it for 3-4 months but now the problem is occuring again. Anyone have any advise?
  • nomad56nomad56 Posts: 134
    rbremer-If the new "computer" died, that's a fluke, and probably WARRANTY" work??? start there.

    If the dealer does not give you a definitive diagnoses, you will have to start troubleshooting the system, to isolate the bad component.

    What "computer" did the dealer replace? Toyo HVAC is a web of sensors, switches and relays. It often requires some electronic testing equipment and skills. Let us know.
  • michanthmichanth Posts: 38
    Dear Townhall,

    I have a 1996 Avalon, Runs Great but I have encountered a problem with my fan. Many times the fan will not active by pushing the fan speed button or by the automatic climate control until until I drive the car over a speed bump at 10 mph or less. I know something elec / mech is loose but have no knowledge of where to look first except for the fuse box under the hood which seems to be fine. And it does not seem to matter if the a/c compressor is activated or not. there is no movement by the fan motor until I go over a good bump.

    Any suggestions before bringing the car in for A/c fan work,$$$$???

    All Help is Appreciated thanks in Advance

  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 58,514
    Does the fan work when the heater is on?

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  • michanthmichanth Posts: 38
    Yes, the fan when running will be active with a/c, heater, and defroster etc.. all combinations of the vent selector buttons. heater on or off, compressor on or off.

    Thanks Mr_Shiftright HOST May 10, 2004 (4:04 pm)
    Does the fan work when the heater is on?
  • nomad56nomad56 Posts: 134
    Michanth-NOT a guarantee, but it is most likely a bad relay. There are several in the Avy's A/C-heater system. A dealer, or good Toyo mechanic is your best bet... they are difficult to test, without proper equipment. Otherwise, the three you want to look at are behind the radio & a/c control panel. To isolate the bad one, you can "tap" each of them and see if the fan starts to run. If this reveals the bad one, go to a dealer or parts store and order a new one. If you are near a "Pick your own parts" yard, this is a great way to save a few bucks. -nomad56-
  • michanthmichanth Posts: 38
    Thanks Nomad,

    I will give the relay thing a try, and at the last resort, I can bring the car in to a Toyota Dealership.

  • pete7pete7 Posts: 2
    Every few days to weeks my climate control system ceases to or starts working for no apparent reason. It has the exact same m.o. each time. The temp. readout does not come on, but the word "outside" stays lit. All of the lights for the fan control and blower position switches light up when you push them with the exception of the windshield defrost and a/c buttons. None of these switches turns anything on, however. The auto button does nothing.

    I suspect it is one of the relays but have no way of knowing which of the dozens it might be. Since the symptoms are so specific, does anyone know what might be the cause?
  • nomad56nomad56 Posts: 134 sounds like the recirc air button is depressed, recirculated air will have moisture in it and fog the windshield worse than you can imagine. Therefore, it will not direct the recirc air at the windshield. Hmmm, A/C should work, though???? ..I am not sure about that button's lack of cooperation, but select FRESH AIR and let me know if we're closer. Otherwise it is more involved, and YES, probably a relay, and there's a handful of 'em that effect climate control. -nomad56-
  • pete7pete7 Posts: 2
    Thanks for the reply. It was not the recirc. button though. None of the buttons works when it is out, even though they light up. Any ideas?
  • nomad56nomad56 Posts: 134
    pete7-Without test equip, this will tough to pinpoint. I would probably do a control panel, then relays, if I couldn't test 'em. I forgot to ask... Which A/C control panel do you have?? These can go bad causing "control" problems. The best way to replace that is from a "pick your own parts" type junk yard. This will save ya' lots of $$$$. Then pursue the relays, since they are hard to test(...and get to) without the right equip. You can avoid trial & error by having Toyo Dlr diagnose it, but this will probably cost a few $$. Sorry for the delay, I am travelling alot right now.

    toydriver-replacement rotors are $80-$90 per/corner. Less if you shop it around. ie) eBay you can get a pair for about $100. Pads $60 to $160, depending on material. It's a "DIY'er" for me, but I think the book lists 2 hrs. -nomad56-
  • tomd14tomd14 Posts: 2
    The engine of my 2000 Avalon (37K miles) has started making a noise (like a trumpet blowing) when I hit the A/C button. A/C runs fine, but noise is rather bothersome. Before I take it in for service, has anyone ever experienced this problem before?
  • wgrimeswgrimes Posts: 2
    I'm experiencing the same symptoms in my '98 Avalon, made more difficult because it is intermittant and usually works when I take it to my auto repair shop. I at first thought it was a fuse but since all fuses checked out OK and because the problem went away, I had to rule that out. My mechanic has tried to run electrical checks and has toyed with the relays but with no luck so far. I promised him that I would bring it back whenever the problem reoccured.

    I'm beginning to suspect that it might be related to outside air temperature, since it seems to work when the air is cooler (I live in San Francisco where cool summer prevail but 100+F temps are a few miles inland) but am still awaiting another warm day. My wife took it to the Central Valley for the weekend so I'll hear about it if it failed again. :-)

    Please let us know if you come up with a solution. I'd take it to the dealer but have had some real problems with sabotage in the past.
  • danbethdanbeth Posts: 17
    Several months ago my inlaws '98 Avalon was experiencing a failure with the speed control for the fan. I checked the past TSBs for their car and found one. The TSB which pertains to your problem is Titled Auto A/C system improvement. # AC005-99. If you have access to an alldata or your mechanic should, look this up. In our case the main problem was a part called the linear controller which on automatic systems controls the fan speed low to high. If you are experiencing one or more of the following: 1) The ambient temp. display may go blank or display"--" 2) Fresh/Recirc indicator light inoperative 3)Mode indicator light inoperative 4) Blower indicator light inoperative. The Parts which will need replacement are the A/C Amplifier(ECU), Air inlet Servo Motor, Servo Link(Damper plate). Should it be only a problem with the fan speed adjustment then the linear controller is in need of replacement. If your car has a manual system then replace the Resistor under the glove compartment near the blower motor. Need less to say the TSB part list is quite expensive. Good Luck
  • A/C noise in my 2000 Av was caused by the drive belt...when I sprayed belt dressing it went away temporarily. I tried to replace it, as the manual says you only have to loosen the pivot bolt and the adjusting bolt. I loosened both to the point of removal, but the alternator did not loosen to where I could remove the old belt.
    Anyone have suggestions?

    Other possible sources of noise are worn bearings of the spinning parts in the A/C & charging system, I also had two blower motors go bad in my 84 Corolla.
    If this is too late and you have already gone to the dealer, please report back with what happened & what it cost to fix. I may have to go in also.
  • Wouldn't you know it-after posting the above I decided to do a little more research. Turns out the manual's charging section describes the situation better. A THIRD ARROW shows the location of the adjusting LOCK bolt which also must be loosened in order for the adjusting TENSION bolt to do it's job. A few scraped knuckles (very tight space) later and the new quiet belt is on and running.

    Tomd14-still am curious as to what your problems were diagnosed as...
  • normnorm Posts: 2
    Same problem with 2002 Avalon. In Auto mode, fan speed and cooling increases below temperature setting but does nothing above setting until max HOT. Dealer replaced sensors without any change. The factory rep (1-800-331-4331) suggests mentioning a "counter-measure" sensor to the dealer to correct the problem. (
  • Yesterday when I started my 1998 Avalon the AC went on for a few seconds then shut off. The outside temp reading also went off. When I restart the car the same thing happened. The car ran fine. Today I looked under the hood and the fans were not running. I found a box with three relays on Fan #3, Fan #2 and I forget the third. Anyway with the car shut off I individually removed each relay the put it back in. When I started the car the AC worked fine. Has anyone seen this? Do the relays reset or will I need to replace them?
  • A very belated thanks. I'll have my mechanic check it out.
  • ncainncain Posts: 2
    After much ado, Toyota sent 2 factory reps complete with test equipment. Net result is that the system is so complex that it is hard to tell if it is working properly. I was convinced that it is working as designed, which leaves much to be desired. The sun sensor on the dash inhibits heat in bright sunlight. Covering it helps in cold weather and eliminates another variable. Just set temp where you want it and wait.
  • ncainncain Posts: 2
    Cover the sun sensor on top of the dash and you will get better response from the heater.
  • Thermostatically controlled heater delivers air that is significantly cooler at dash resisters than floor registers. Dealership states that it is normal. I find it uncomfortably cool and generally must increase thermostat setting to ~80 deg. Can this be adjusted?
  • Some car models divide the heater outflow between the upper and lower vents using the same temperature air. Others "bleed" in a certain amount of ambient (outside) air to the upper vent, causing the flow to be cooler. I personally prefer the latter.


    You may be able to reduce this cooling effect by switching to recycle mode, where interior air becomes the primary component of the "bleed".


    Don't forget that vent air directed at your head will feel cooler, even if it is the same temperature as air directed to your feet -- the so-called windchill effect.
  • finfin atlantaPosts: 591
    If you have an XLS and expect the auto-temp setting to work, good luck. This is a known problem with Avalon's and is much discussed in posts here on Edmunds. It may be, over the years, one of the worst faults Avalon has. Scroll back thru the discussion and read all the comments and suggestions. As you will read, not all XLS Avalons have the problem but many do. The auto-temp simply does not work effectively. I drive an XL for this reason, as do others who post here. The new model may fix this. Hope.
  • I have owned BMWs in the past and they also "allow" cooler air to come from the top vents. The Volvo 240 I had years ago had a rotary knob that would control the duty cycle of the air conditioner and that was a real neat feature (could control the humidity level instead of air on or off; sorry, off topic). The cooler air up top is usually desireable and helps to keep the driver more alert. I think the idea is to keep most of heat down by the toes and it will mix with the cooler air . I do agree that the auto temp control isn't the best and I also have to keep the temperature (at least what the display reads) higher than what I would expect. Seems like there is a large hysteresis in the control. Options to help would include partially closing the top vents or manually controlling the air to the floor.
  • nospamnospam Posts: 54
    I have a 99 XLS with climate control. The 4 fan speed buttons do not change the speed. It stays on low. All the other buttons work fine. Does anybody know how to diagnose this? I tried to replace the blower motor resistor only to find out the XLS doesn't have one. After doing more research maybe it's the a/c amplifier located behind the radio? Has anyone had this problem before? If so what fixed it? Thanks
  • jhiujhiu Posts: 1
    Hello DanBeth,

    I'm having the same problems with my 98 avalon but can't seem to get the folks at a local dealer to order me the parts. The problem is they can't find the parts based on your description. Is there any chance that you have the part numbers for the three items? If you do, please forward them to me at Thank you kindly.

  • danbethdanbeth Posts: 17
    I am sorry I have not sent these part numbers earlier but I have not been on this forum for months. Toyota should have the TSB I listed as AC005-99 titled Auto A/C System Improvement. # 88650-41030- A/C Amplifier(ECU), #87106-07050- Air Inlet Servo Motor, #87151-07010-Servo Link(Damper Plate). This is a very expensive replacement. If the only problem you have is the high to low variation not working, then the Linear controller replacement is the only problem. This item is the controller on XLS models which have the auto-climate control feature. If you had a non-automatic climate control then the blower motor resistor would be the part. By what you are saying It sounds to me that you need the linear controller only. That part number is #87165-32010. Good luck and have them replace this part first before you move on to the other parts as outlined at the beginning of this paragraph. Thanks Dan
  • I have a 2000 Avalon XLS with 71,000 miles. It has never had it's AC filter changed. The dealer wants $45, which seams high for a filter change. I would like to do it myself. I know that the filter is located behind the glove box, but am not sure how to access it. Any experience or suggestions? Is the change even necessary?
  • bwiabwia Boston Posts: 1,945
    At $45 that price seems extremely low. I change my AC filter every summer and it costs about $75. I believe the part is $39 so your dealer is doing you a favor. Maybe he wants you to buy your next Avalon from him.
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