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Toyota Avalon Climate Control Questions



  • Looking at purchasing a 1998 Avalon XLS. Only problem owner has had is the air quits running cold whenever it rains. Then works fine again whenever it dries up. Took it to Toyota and they couldn't find out what's wrong. Even sprayed inside hood but air worked fine then. Just not when it rains. Anybody else heard of this and know the solution?
  • texasfx35texasfx35 Posts: 65
    I have a '07 XLS. A few times over the years, the A/C would stop cooling during rains when we ran through water puddles. Simultaneously, the A/C switch in the cabin would blink. The Toyota dealer tightened the tension on the belt driving the compressor and the problem has never reappeared. Apparently, the compressor clutch can slip on the belt if it gets wet and the tension is not proper.
  • do you have an '07 or a '97? You said "over the years" so did you mean '97?? I would hope you wouldn't be having problems with a brand new 2007 car. Thanks for your reply. If anybody else has had this problem, please reply. Want to see if problem can be fixed before we purchase car.
  • oilslickoilslick Posts: 14
    when it gets over 90degrees, it seems like the AC quits working on my 98 Avalon. Has anyone seen this before and what causes it? Thanks.
  • texasfx35texasfx35 Posts: 65
    Yep, it is a '97.
  • mvbowensmvbowens Posts: 1
    My brother has a 95 Avalon that the ac works and sometimes it doesnt. I think it is the expansion valve on the evaporator. I think you have to replace the entire eveporator.
  • To those who wonder if they have r12 or 134, a way to tell is to look at the hookup point on the low pressure side that you use to recharge it with. The newer r134 is a larger diameter fitting which you push the recharge or gauge hose onto by squeezing the lock ring up then slide it in and release. The older r12 has a screw on fitting just slightly larger than the valve stem on your tires. Sometimes you can spot r12-134 fitting adaptors that were installed if your car ac was converted to r134. :shades:

  • captain2captain2 Posts: 3,971
    use of r12 for anything has been outlawed since the 90's - car a/c systems are almost universally r134 for quite some time now. System conversion on older cars is also federally mandated.
  • intermitingly the blower fan goes out and also the outside are temp. display gose out on instrument cluster at the same time. i was thinking of replacing the heating and air conditioner do to the fact that the outside are temp. desplay gose out. what do you guys think?
  • dedatdedat Posts: 1
    Have an 07 Avalon that been back to dealer 3-4 times because when the AC is on the passenger seat heater cycles on and off. Any ideas? Dealer has traced wires checked sensors etc. and appears to be fixed at the dealership until it arrives home
  • Just had the same problem. Lights on the buttons worked but no blower,a/c,outside temp display. Left it at the dealer because nobody else would touch it. He said it was a servo?..and an amplifier??. $830.00!!! wont work with out it.
    Ofcourse it's December, so whatam I suppose to do?
  • I am pretty handy mechanically and I need to change the condenser (of course the dryer too once I get the condenser installed)out because of a leak. Can someone direct me to how I do this? I have looked at the car multiple times to see how to extract the condenser.
    Any help as to how to do this or what shop manual is best to detail this?
    I usually work on BMWs and Bentley is the best BMW manual but have no clue about this Toyota...
  • i just purchased a new 2007 Avalon two weeks ago and now the driver's seat heater appears to always be on even though the switch says it's off. Have they found a fix for your problem yet? My other problem is the automatic rain sensor doesn't work properly.
  • iamknottiamknott Posts: 82
    I purchased my 2007 XLS in late March. Now that we are finally getting some hot and humid days, I notice that when I turn on the a/c, the climate control automatically goes to recirculate mode until the car cools down. This is the first car I've had (including other Toyotas) that did this. In the past, I've always had to choose recirculate and I'd like to retain that pattern. Is this something that can be programmed out of the Avalon? You might wonder why it bothers me. My car sits outside all day with the windows closed. So, when I get in, the air temperature inside the car is higher than it is outside. Therefore, the a/c is trying to cool hotter air than it has to and I believe that it actually takes longer to cool down the car.
  • wwestwwest Posts: 10,706
    Yes, there is a c-best option (FINALLY...!!!) that the dealer can set that alleviates this problem. You may note that in your owners manual they advise you to drive for the first few miles to "flush" the passenger cabin of HOT air in this instance.

    I have never understood this recirculate "feature". Adverse, WRONG, thinking insofar as I'm concerned.
  • Have a very frustrating problem with heating in a 2001 XLS with automatic climate control (selective for driver and passenger).
    As far as I am concerned, this is nothing but a headache and much prefer the manual system for reasons of simplicity.

    The problem is in the HEATING aspect. When you require heat, only the driver side vents throw out heat and very faint heat on the floor level.
    The passenger side simply freezes..just cold air both on the feet and vents. The problem is, you cannot shut off the vents on the passenger side either and so the car is heating on the driver side and cooling on the passenger side. We have to carry blankets to cover up and stay thawed for the passenger.
    Went to Toyota dealership and they say that some vent is just dangling in the heatt/cool unit under the dash and the whole unit(RADIATOR part no 87050-07111) will have to be changed. The unit costs $2381.90 cdn. and labour added, will cost $3214.35 cdn.
    For a 6 year old car, this kind of thing should never happen. Never a problem in my Audi or my Saab.
    Anyone out there with a similar problem and any diagnosis, please share your genius.!!!????
    Yoyota should be ashamed...
  • Forgot to mention on the above...
    The air conditioning works fine on both sides...plenty of cooling and acceptable temperature control on both sides.
    The problem is just with no heat on the passenger side.
  • Hello all,

    I have a 1998 Toyota Avalon XLS in mint condition with 240km on it. We are the second owners and everyting works great except when you start the car the climate system automatically switches to recycled air and will not shut off until you manually switch it to fresh air. We had the problem addressed which worked for about two days and then returned. I am told that it needs a $500.00 part under the dash that tells the damper motor what to do. Does this sound correct to anyone? Also, living in Canada and heating in the winter is very necessary. The car heats up fine it just won't defog the interior windows. I have seen this before on some GM products but never to this extent. I drove it last night and with the exception of the front windshield I could barely see out of the car any where else. Should the defog and defrost function not take care of this? What might be the problem. I am new to this site and may experience difficulties navigating around but I will respond to a read all responses as soon as I find them. Any help would be appreciated.

  • Thanks wwest. I appreciate the input.

  • mdealmdeal Posts: 2
    I too am having problems changing out a air filter on my 2000 Avalon
    Bought one from auto parts store & the directions that came w/ it
    are diffrent than my year.Instead of a phillips screw for the glove box stop,it
    is some type screw you have to line up w/ a slot to remove.Any help
    would be great.
    Thanks MIke
  • rsh1rsh1 Posts: 1
    My husband and I purchased a 2007 Toyota Avalon Ltd in the fall of 2006; overall we are extremely pleased with the vehicle. However, there is a foul smell coming from the air vents when a/c or outside air is on. The dealer says that the recommended fix is to simply spray lysol into the vents from under the hood. Seems to me that only masks a deeper problem. Anyone have this problem?
  • tjc78tjc78 JerseyPosts: 6,409
    The dealer is right. There is most likely a touch of mold in the ducts. The Lysol will typically cure it.

    2017 Buick Enclave / 2017 Hyundai Elantra

  • amauhryamauhry Posts: 55
    Kill the fungi first (any bacteria disinfectant spray may do the trick). If left alone, your situation will reoccur, and then you’ll have to spray more Lysol again.

    Long-term solution: right after using the AC on hot & humid days you should run the blower (AC off) at high speed and in heat mode for about 2 minutes. Use “outside air” mode; not the “recirculated” mode. This will dry the ducts and evaporator fins and coils leaving no room for mold and mildew to grow.

    '08 Limited
  • wwestwwest Posts: 10,706
    Contrary to the above, it will take at least 10-15 minutes, typically, but up to an hour to raise the temperature of the 10,000 square inches of evaporator vane surface area enough to have the remaining thin film of moisture thereon begin to evaporate into the airstream. The operational "target" temperature of the evaporator is ~34F.

    Absent modifications to the system your best bet is to leave the windows down slight each and EVERY night provided the car is under shelter.

    For a really viable modification go to:

    And read up on their EED, Electronic Evaporator Dryer.
  • wwestwwest Posts: 10,706
    The heater core is ALWAYS downstream of the evaporator core so it does no good to turn up the heat when attempting to dry the evaporator. And just how long it will take for the thin film of moisture to begin to evaporate off of the near freezing evaporator vane surface area is a function of the outdoor climate. Your 2 minute "estimate" would imply an OAT of >100F and an Rh of <20%

    And this "condition" is not restricted to HOT and Humid days, most modern day climate control system run the A/C all year around (primarily for dehumidification during the heating seasons) and so the evaporator vanes can be literally "choked" with moisture at any point the A/C is switched off.

    The growth of the microbes leading to the "dirty gym socks odor" is primarily between 60-70F in a dark, moist, "dank" environment. Say in your heated garage at night in the dead of winter.
  • mashoudmashoud Posts: 8
    The Avalons are notorious for Heating and Cooling problems and if you write to Toyota, you would not even receive a reply.
    As for the "fungal' problem and the stench, it is more likely that the interior cabin filter is plugged tight with pollen and debris and the stench starts there.
    I would change the filter which is located just under the glove box.
    You would find it black with moss and slime from the moisture.
  • wwestwwest Posts: 10,706
    "Avalons are notorious..."

    As are LS400's, RX3X0's...

    In point of fact almost all passenger cars of asian origin since they primarily use HVAC designs, horribly FLAWED HVAC designs, by NipponDenso.

    I think I have read that the newer LS430's have a UV light inside the A/C plenum to belay/retard the growth of these microbes.

    Even worse, many US marque are now also suffering, due to this design flaw, as a result of the presence of NipponDenso in our shores as Denso US.


    Pollen filters undoubtedly help to prevent the formation of mold and mildew spores/microbes through denying them the "food" they need for growth. That isn't to say that an overage pollen filter wouldn't be a heavy contributor to bad odors.
  • amauhryamauhry Posts: 55
    Forgot to mention that for an effective killing, the bacterial disinfectant must be sprayed in the evaporator area (the entire core), since this is where most of the fungi are located.

    This also means that you have to do some "digging" in order to have access to the evaporator.

    '08 Limited
  • amauhryamauhry Posts: 55
    I haven&#146;t yet seen an HVAC system where the heater elements follow the evaporator coils. I have taken apart my own house HVAC (forced air, upright setup) where the heating elements (heat exchangers by natural gas) PRECEDES the evaporators coils and fins of the refrigeration cycle. This OEM setup is not pure coincidence; the HVAC manufacturer is using the heating season to kill a potential house problem, which could easily develop during winter under the coziness of a non-conditioned equipment room located in a cold, damp basement. True, during winter I know that the air is dryer (I have measured 24% rh in my house; I keep a well-calibrated hygrometer, with NIST traceability, in my basement), but I&#146;m aware of damped basement here in NYC during winter.

    I do not doubt what you&#146;re saying about the arrangement of the heater and evaporator in a car&#146;s HVAC, but I haven&#146;t seen it yet. If you could prove that your arrangement is the rule-of-thumb for car&#146;s HVAC (schematics for example), then I will learn something new and shut up.

    I have never, ever have a problem with foul smell in any of the car I&#146;ve owned because I practice what I&#146;ve explained earlier.

    &#146;08 Limited
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