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Toyota Avalon Climate Control Questions

124

Comments

  • amauhryamauhry Member Posts: 55
    My hat’s off for you wwest. Indeed, I looked at the HVAC system diagram for the Avalon ’08 and the heater core is downstream of the evaporator. They do share the same compartment however. As I said earlier, I never saw this arrangement before since I’ve never experience HVAC issues with any of the cars have owned so I have not had the need to explore this field (in cars) with details, and that prompted me to not disregard your theory completely.

    Is this the de facto arrangement for all cars? I do know that my practice of running the heater has saved me from smelling bad odors stemming from the air vents ; perhaps because of different configuration? Or because these two units are next to each other in the same compartment hence sharing the same air volume?

    Again, thank you from making me dig some info “new” to me.

    BUT let me tell you that your recommendation of leaving the windows down makes
    sense only IF each and every night the RH of air is about 60% or below; otherwise, with high RH values your suggestion won’t work. And I’m sure you know that is very difficult to get those 60% or below RH values outdoors during the summer season. Also the 34F temperature at the evaporator coils is more of a design value than an actual value. My house HVAC with a SEER of 15+ has always measure an average of 40F at the evaporator (with identical indoors temperatures and wet-bulb temperatures)
  • wwestwwest Member Posts: 10,706
    Sorry, I would have said "automotive" HVAC systems had I known the post was that open to (mis-)interpretation. And if you can figure a way for an automotive A/C to be used efficiently for dehumification with the evaporator downstream of the heater core I'll pay for the patent attorney.

    "If you could prove..."

    I have no need to go "there".
  • wwestwwest Member Posts: 10,706
    Wow, you're giving me a lot to answer "for".

    Not long after you shut your car off in the evening after a day of A/C use the HVAC plenum area will rise to EXCESSIVE RH, possibly into the level of SUPER-SATURATION. The idea is to let the passenger cabin acclimate to the "local" Rh, not leave the elevated RH or super-saturation condition exist overnight, night after night.

    And your home HVAC system DOES NOT have a thermistor mounted on the evaporator downstream surface to prevent the controller from allowing it to go below FREEZING. If you home's system ever has INLET airflow conducive to the evaporator freezing over you have a really serious problem.

    "design value rather than an actual value.."

    No, in a modern day automotive the HVAC system is more often used ONLY for dehumidification rather than both cooling and dehumidification. During the winter months the airflow ENTERING the automotive HVAC might readily be low enough that the evaporator would easily freeze over if not prevented from doing so by the control system.

    Addtionally I rather doubt that your home system has a remix/reheat mode as does almost all modern day automotive HVAC systems.
  • amauhryamauhry Member Posts: 55
    If your “local” RH is 90% night after night, you don’t need SUPER-SATURATION for fungi to grow. Any number between ~ 65% to 100% RH on a daily basis will happily support fungi life. Guaranteed.

    Why do you want my house’s HVAC to have a thermistor? I’m quite sure that the TXV valve my system has does the job a whole lot better and efficiently, since it monitors the Freon R22 state across the evaporator, self-adjusting the fluid’s pressure (hence its temperature) accordingly.

    The remix in your “remix/reheat”mode is not practical for home application; first, most home are not made of glass; second, even if they were, there would be no need to instantly defog the “windshield” of such houses as would be in a moving car, say, during winter; third, …. Properly sized residential HVACs significantly lowers RH levels with the use of AC during the summer, and their heated, dry air “dehumidify” even more during the “dry” winter. Most residential HVACs, especially those with an SEER of 10 or higher, are more efficient than automotive HVAC’s, where efficiency is sacrificed for compactness.

    About your “reheat” mode? Yes, my 6-ton HVAC is always in recirculated (summer) or reheat (winter) mode; I couldn’t think of my electric/gas bills if this monster had a “fresh” air intake mode; ain’t just practical for home HVACs.

    Amaury
    ’08 Limited
  • wwestwwest Member Posts: 10,706
    "You don't need SUPER-SATURATION for the fungi to grow."

    Even with clothes freshly out of the washer you can hang them outside to dry and the disparity between even 100% Rh and the wet clothes will result inthem being dry within a few hours.

    The point is that even 100% relative humidity does not equate to prevention of enough evaporation to reduce the level of moisture wherein the A/C plenum getting below the level in which it would support microbial growth providing even a small level of convection airflow is made available. Forced airflow, even better.

    "Do you want my house's HVAC to have a thermistor?"

    No, my point was that automotive systems, wherein absent "control" the evaporator might freeze over, your "house's" HVAC will likely never "see" that threat.

    "The remix in your "remix/reheat" application is not practical for home application;"

    Well, not only is it PRACTICAL, the remix/reheat method is currently in daily use in many homes, for the very same reason for which it is used in automobiles.

    Most are standalone DE-humidifiers but some more upscale homes actually use central heating and cooling in combination, simultaneously, to both cool and dehumidify the home and increase human comfort levels. Obviously the highest level of dehumidification would be attained with the evaporator operating at the lowest possible temperature thereby oftentimes requiring the use of the reheat/remix application/method.

    And the actual numbers, temperature range, for microbial grown is 65-75F.

    And IMMHO automotive A/C system efficiency could be quite significantly improved (along with FE) via ALWAYS using recirculate and somehow bypassing the reheat/remix mode during the cooling season when there is no THREAT of/from windshield fogging, INTERIOR windshield fogging anyways.

    During the summer months, cooling season, I always set my automotive A/C system to the maximum cooling level (it then automatically switches to recirculate) wherein the reheat/remix vane/door remains firmly SHUT, and then I manually adjust the blower speed to meet my cabin cooling needs.
  • amauhryamauhry Member Posts: 55
    The only one reason automotive HVAC combines heat mode with cold mode is because the driver needs that function during the not-so-often humid instances of the winter season so that he/she has clear sight through any of the car’s glass surfaces as quickly as possible. In this combined mode, the A/C is used solely to remove moisture on the spot from the windshield, and the heat, though it removes further moisture, is provided mainly for the driver’s comfort (remember, it is winter).

    You should know better. Air conditioning not only cools but dehumidifies (removal water molecules from the air) at the same time, or did you forget about the dripping water from window A/C units? Where do you think that water is coming from?
    In my 6-ton unit, it is a continuous flow of water through a ¾-inch black PVC pipe connected to a drain. So why the need of heat, especially in the summer, to remove house humidity when the A/C does it better and cheaper by itself? I’d feel sorry for those home owners with such an option on their HVAC system not because of their wasted money (in case they’re filthy rich) but because of their ignorance.

    There’s no need for this combined heat/cold mode for a home, and such an option would be redundant and a waste of energy both on the cold and heat side.

    Amaury
    ’08 Limited
  • nimiminimimi Member Posts: 249
    Since you guys seem to have HVAC down pat, can you tell me why I DO NOT see puddles of moisture under my '08 Limited after I park the car and having run the AC?
  • tjc78tjc78 Member Posts: 15,918
    That is surprising... my '06 has a mini flood underneath it after I park. I live in NJ which is always humid..so that could be it. Keep an eye on it, you could have a plugged drain tube, which could cause it to overflow into the car.

    2023 Mercedes EQE 350 4Matic / 2022 Ram 1500 Bighorn, Built to Serve

  • amauhryamauhry Member Posts: 55
    Minimi, because there is a hose constantly draining the water from your A/C to the outside (vehicle’s undercarriage). Wanna see it? After running you A/C for some time, park your car (think safety first!). Wait less than a minute. Then take a peak underneath your car by the engine area. You gonna see the water (from the A/C evaporator) dripping + the puddle just like tjc78 suggested.

    Actually, the evaporator core has a drain pan (or condensate pan) where it collects the water from the moist air being ‘conditioned’. A hose connected to this pan drains the water to the exterior, underneath the vehicle. The design is such that water flow throughout the drain system is by gravity.

    Amaury
    '08 Limited
  • amauhryamauhry Member Posts: 55
    My apology for misspelling your user-name nimimi. Precisely the drain house should be somewhere past the engine area by the driver’s area but in the undercarriage section.

    Amaury
    '08 Limited
  • nimiminimimi Member Posts: 249
    Thanks, I'll crawl around and see what I can see. I'm in the hot, dry part of Eastern WA and I have noticed the smell when I drive around in the morning with only the fan blowing.
  • wwestwwest Member Posts: 10,706
    Maybe we should have a conversation by phone.

    "not so humid" "winter season"

    I grant you that there are some instances, TOTALLY RANDOM instances, wherein an automotive A/C system can be of help in dehumidifying the COLD and DRY incoming airflow in order to PREVENT windshield or window fogging. It MAY even be of some help in removing condensation from the windshield once it is present.

    But as you most correctly point out, during the winter season the atmosphere is "not so humid", PREDOMINANTLY of low humidify. Since the Automotive A/C system CANNOT be allowed to drive the evaporator surfaces below freezing, or not even very close to the freezing level, the probably of the system driving the temperature of the COLD incoming airflow down to its DEWPOINT, the point at which airborne moisture begins to condense out of that airflow is TOTALLY RANDOM, a function of mother nature ONLY.

    "There's no need for this combined heat/cold mode for a home, as such an option would be redundant and a waste of energy both on the cold and heat side."

    "I feel sorry for those home owners with such as option on their HVAC not because of the wasted money (in case they're filthy rich) fbut because of their ignorance."

    Methinks you just inadvertently labelled over 50% of automotive owners as being ignorant. Not only does that ignorant class constitute a HUGE market for standalone humidifiers and dehumidifiers to increase their comfort level at home they also use a combined cool/heat mode in their automobiles NEEDLESSLY.

    The automatic climate controls in my '01 AWD RX300, my '01 911/996, and my '92 LS400 have all been modified so they do not NEEDLESSLY waste energy by first COOLING and the REHEATING the system airflow at any time of the year.

    My '92 LS400 gets the coolant control valve for the heater core wired firmly closed during the cooling season and the A/C compressor clutch circuit disconnected during the winter months.

    The 911 has a DIY switch mounted in the console glove box to disable the A/C compressor during the winter. My RX300 has two c-best options in this regard. The first is set such that I can turn the A/C off ONCE and it will remain off INDEFINITELY until I turn it on again, "enable" it, manually. The second option is set such that the A/C is unlinked from operating automatically in defrost/defog/demist mode.

    Applying HEAT to the inside surface of the windshield will ALWAYS be the most reliable way of preventing condensation AND removing condensation once it has formed. I'm not against, absolutely not, the use of A/C as an aid for these things but absent my body finding a way to know that the current dewpoint is conducive to same I will continue to rely, first and foremost, on HEAT.

    To most quickly COMBAT windshield fogging in my '92 LS I have a switch mounted under the dash by my left knee that when actuated adds a slight resistance to the IAT (Internal Air Temperature) sensor such that the climate control ECU "thinks" the passenger cabin has suddenly gotten VERY COLD.

    If I see condensation beginning to from on the LS's windshield I actuate this switch and then switch the system to defrost/defog/demist mode. The ECU reacts to the DIY switch by changing the system to HEATING mode and raising teh blower speed.

    In the case of the RX a quick clockwise twist of the cabin temperature setpoint knob accomplishes the same task.

    The 911, when switched into defrost/defog/demist mode will ALWAYS react with HIGH HEAT and HIGH blower speeds, even on the hottest day of August.

    So, two bottom lines.

    You can improve the FE of your vehicle via somehow bypassing the reheat/remix mode winter and/or summer.

    Human comfort involves not only the surrounding air temperature, and the radiant effects of our surrounding environment, but also the Rh of the surrounding atmosphere, with 40% being within our comforts zone.

    Now, once our A/C system has cooled the home's interior atmosphere and surfaces to our selected comfort level how does it compensate for humidity above 40%, well above 40%, absent using a reheat/remix system..??

    A portable de-humidifier...??
  • wwestwwest Member Posts: 10,706
    While here on the "wet" side of the state my A/C drain hose drips water almost constantly, that might be a fairly rare thing for your A/C on the "dry" side. So, you shouldn't really expect to see any drainage unless the Rh has been fairly high for the previous period of A/C operation.

    How high..?? Enough to result in A/C drainage... ;)
  • amauhryamauhry Member Posts: 55
    "I feel sorry for those home owners with such as option on their HVAC not because of the wasted money (in case they're filthy rich) but because of their ignorance."

    My friend I respect your knowledge (truly), but I was referring to residential HVAC, since you said that “…the remix/reheat method is currently in daily use in many homes, for the very same reason for which it is used in automobiles”. Notice that I used the noun “home owners” and not “drivers”.

    I mean, it’s damn good to have this great exchange of ideas.

    Amaury (mechanical engineer)
    ’08 Limited
  • wwestwwest Member Posts: 10,706
    Sorry, I quoted the two statements out of order, and put them in a different sequence in order to make my point.

    The point that I was trying to make was that if, as you stated, the use of a reheat/remix cycle in a residence shows ignorance on the owners part then that implies, by default, that most modern day owners of vehicles with automatic climate controls are also ignorant.

    But in reality it is the automotive manufacturers that continue to insist on using an outdated, FLAWED and patently unsafe HVAC design in our vehicles.

    Interior windshield fogging should be considered a COMPLETELY separate issue vs keeping the occupants comfortable.

    First, almost all home dehumidifiers use a reheat/remix cycle.

    I'm from the south, AR, originally and even when the air temperature is quite satisfactory, <75F, you might still be miserable inside your home with 90% humidity. How do you get comfortable in that situation..??

    If you already have A/C you might well want to run it to dehumidify the inside atmosphere, but now the interior temperature will likely get discomfortingly COOL unless you somehow reheat that atmosphere you just cooled.
  • rpfingstenrpfingsten Member Posts: 154
    nimimi..

    Thats strange.. I have an 07 Avy and there is almost always a puddle of water on the garage floor after running the a/c. But I do live in Louisiana where the humidity is outragiously high..

    Roland
  • amauhryamauhry Member Posts: 55
    I live in the east, New York City to be precise. This region seldom experiences what you&#146;ve described. Usually we get high humidity accompanied with temperature increase or vice versa. Obviously ambient condition for the eastern part of this county do not call for residential HVAC with the remix/reheat mode; so, I guess, this system is not sold or rarely sold around here. If it is, it would be redundant to have the remix/reheat function.

    Based on your explanation, it makes perfect sense to have one of these for home application in your area/region. Kool!

    I did not mean to offend anyone about being ignorant. And the fact is, we don&#146;t know everything. Why do you think I joined this site in the first place? My knowledge is not absolute my friend, and the potential for learning from other people&#146;s experiences is what makes forums like this…well...PRICELESS.

    Amaury
    &#146;08 Limited
  • amauhryamauhry Member Posts: 55
    ...and, of course, that makes me share my own experiences and point of views.

    It is a win-win situation, and we all are the beneficiary :)

    Amaury
    '08 Limited
  • wwestwwest Member Posts: 10,706
    I would imagine that even in your area of the country there would be a fairly large number of people that would be comfortable with the elevated temperatures were the Rh not so high.

    But that's where those portable dehumidifiers (COOL an then REHEAT) probably sell like hotcakes.
  • belaircarguybelaircarguy Member Posts: 107
    I live in an area of the country with high summer humidity. I operate the A/C in all my vehicles in the recirculation mode all the time all summer. Many newer vehicles (first one I had was a 98 Olds minivan) have an interior air cabin filter. This is generally located on the lower part of the dash on the passenger side (but check your owners manual). These filters will get dirty and musty and create that foul smell when the A/C is turned on. Never really noticed it with the heater, just the A/C. Open the small door / cover for the filter and pull the filter. Take it to Pep Boys or your favorite auto supply store and get a replacement. I change these in each vehicle once per year and no more smell. I found this by experiencing the same smelly problem until I discovered this quick and easy fix.
  • manav82manav82 Member Posts: 16
    I own an 07 Avalon. I used the heat for the first time this fall and have noticed white powder coming out of the vents. :confuse: The rear seat and dash have a thin layer of this powder on them. I have checked the filter and it is clean. Has anyone else seen this or have any ideas? Thanks.
  • bhawksbhawks Member Posts: 2
    I have an 06 Limited and had this problem one year ago. They replaced the condensor and just last week, this happened again and they are replacing the condensor again. Evidently there is a service bulletin out there on this. Also, in repairing this, they have to take apart the whole dash and center counsel. Took three days to have this done both times and the first time I had to take it back about 3 times to get all the rattles fixed from them messing with the dash and such. Have not picked it up from the second repair but I am dreading the inevitable rattles. Would like to know what this particulate is made of and if there are health issues with inhaling it, I assume it can't be good, but have not found the info. :lemon:
  • manav82manav82 Member Posts: 16
    Thanks for the post. Any idea what the TSB number is so I can let my dealer know. Thanks,

    Manav
  • bhawksbhawks Member Posts: 2
    No, sorry I don't but when I pick up the car tomorrow I will see if I can get a copy. If I don't get it, just tell the dealer to call toyota as they do know about this. Good luck
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Here you go:

    Issued: Tue, May 27, 2008
    TSB Number: SB0075-08
    Title: Air Conditioning - Excessive Dust From Vents

    Visiting Host
  • wathanwathan Member Posts: 1
    I too have an 07 Avalon with the dusting problem. Mine started in Sept. 07 the day after I had service done which included changing the cabin filters (maybe a coincidence). I thought it would stop, but it kept getting worse. With the holidays and being busy I never took it back in to the dealer until Jan. 5th. They've had it 3 days and say it will be ready on the 4th day. They said that the evaporator had a "new" coating on it that caused a seal to deteriorate causing the dust. My concern is what the health hazards are for breathing this dust for the last 3 months? Anyone know how to find out? I haven't had as much as a cold for several years and now since November I've been fighting upper respiratory problems - can't help but think they're related.

    Any thoughts?
  • amauhryamauhry Member Posts: 55
    If they were messing with your dash, then they weren&#146;t changing the condenser. Condenser location is next to the radiator in the engine compartment. Evaporator location, however, is by the dashboard.

    The evaporator is just a whole bunch of copper tubing and aluminum fins held in place by solder (simplified explanation). Then you have the refrigerant (R134a) flowing inside the tubing. Nothing in there is supposed to release any powdery substance unless the copper tubing and/or fins were dirty/contaminated in their exterior surfaces when Toyota assembled the car.

    Or it could be that the ductwork material was internally contaminated/dirty at the time of assembly. The refrigerant is out of the question; when it leaks, the refrigerant does not leave powdery stuff.

    Last but not least: the heater core. Air first blows through the evap then through the heater core. Any contamination in the exterior of the heater core could be a valid reason for this problem too.

    Amaury
    &#146;08 Limited
  • wwestwwest Member Posts: 10,706
    Back in the early ninties Lexus "experimented" with the use of a porus coating on the evaporator vane surface area into which, into the pores, was embedded an anti-microbial chemical. The rumor is that this early practice was discontinued once it was realized that no MSDS from had been filed with the US.

    This was to combat the growth of microbes which constitute the mould and mildew odor, "dirty gym sock odor" many of us are now so very familiar with.

    This lead to many problems and the practice was discontinued until it could be "perfected".

    "perfected"

    NOT...

    The source of the "dust"....

    The embedded chemical has long since been washed away by daily A/C activity (takes as little as 6 months) and now the porus coating is breaking down due to those day to day "washings". You will in all probability be getting a new A/C evaporator absent the porus coating.

    Another experiment that didn't work.

    My understanding is that the new LS's have a UV light source mounted near the A/C evaporator to help combat this problem.
  • BobWSBobWS Member Posts: 2
    I am,according to the folks at Toyota,the only person in the universe with this problem. We bought a brand new 2007 Avalon Limited in May 2007. From the 1st time using heat the car will on occasion kick the heat to maximum Then we have to hit the buttons to bring back to normal. It has done it several times on say a trip from Buffalo to Syracuse-then it will go weeks and weeks and not do it

    Of course it never acts up for the dealer!! The arrows indicating where the heat is going will change by themselves and then last week the radio came on by itself! ( This week the windshield washer bottle emptied out because the bottom hose fell off. Dealer fixed that)

    Anyone experience any of these? Otherwise the car is great actually.
  • mitch1947mitch1947 Member Posts: 7
    I believe it's normal for the arrows to switch automatically from the floor and dash vents depending on the temperature required. I also had the same problem with the windshield washer bottle and there is a TSB (TSB BO 008-07) for the 2007 Avalon and it involves replacing a hose, joint and related washers. I haven't had the mystery radio come on by itself. If you have the heat set to automatic the fan will increase in volume as the car warms up but it should automatically decrease when the desired temperature is reached. I did have one weird problem - the heated seats stayed on even when the switch was in the off position and of course it couldn't be duplicated at the dealership. It only did it one day and it's been fine ever since. I hope they find out what's causing your problems.
  • ronwuzhere2ronwuzhere2 Member Posts: 2
    my avalon recently started running on low even when i switch it manually to high. sometimes it will go to normal speed then to low and repeats. no pattern to it just random. checked the blower and it's fine. i've read that the xls does not have a resistor but then i have no idea what would cause this. any ideas would be greatly apprecciated.
  • gregoryd73gregoryd73 Member Posts: 1
    Anyone know if the '95 Avalon XLS has a cabin filter behind the glove box, like later models?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Not it doesn't. That's comes in about 1999 on the Avalon I think.
  • wilsongk1wilsongk1 Member Posts: 1
    A/C blowing hot air. Going to take it to an independent shop, but wanted to see if there are any issues that might cause this besides needing a new compressor. Any Ideas??

    Thanks
    KW
  • jeal1jeal1 Member Posts: 4
    I posted this question in the 2008 Toyota Avalon section and then came upon this forum. So, here it is again.
    When I set my Avalon's passenger temperature to anywhere between 74 and 80, the back vents blow out air at 107 degrees which makes it impossibly hot for anyone in the back seat. The passenger in the front has to freeze or the back seat passengers have to burn up. Anyone else having this problem?
  • tjc78tjc78 Member Posts: 15,918
    I don't think its a problem at all. From what I remember from when I had my '06 Avalon that is just the way it works. FWIW I never had to set the heat above 68-69 or the car blew me out of there it was so hot.

    2023 Mercedes EQE 350 4Matic / 2022 Ram 1500 Bighorn, Built to Serve

  • cowboy88cowboy88 Member Posts: 4
    I am hoping someonce can help or has worked through this. My wife drives a 1997 Avalon XL. Has about 130k. The car gives very little heat. The engine does not overheat. The AC works fine. However, you have to be driving for a while with airflow on recirculate to build up any significant heat. I've had the timing belt and woater pump replaced just this past summer (July 2009). I use long life coolant whcih is reccommended by the dealer and there are no coolant leeks.
    Please help! My wife hates the cold!!

    Tony
  • finfin Member Posts: 594
    Here's some general thoughts, others will have to give you more exact details. Your cooling system works, the car operates and does not overheat or leak. That means the warmed coolant is not getting to the heater core that allows the heat to be blown to the interior of the vehicle.

    There is a control valve that diverts coolant to the heater core. This valve is not opening. Or the hose to it is stopped up due to age. Or the heater core is plugged in places with residue. Or the control switch is not telling the valve to open. Or the return line from the heater core is plugged. Or a combination, this is a 13 year old car. (It's not the coolant or the water pump.)

    A coolant flush with the new pump should have revealed the problem. But if you just had this work done and have never had the problem before, the repairs may have caused the problem. In order of simplicity, step one might be to ask the dealer to check his work and see that all lines and wires have been properly re-attached. After that, check the valve and hoses. Last, look to the heater core. Hope this helps...
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Aside from the possibility of a defective heater valve (good guess!), did they replace the thermostat at the same time as all the rest? If not, they need to be slapped. :P
  • wwestwwest Member Posts: 10,706
    I will assume the heating was fine until last summer so your most likely problem is a "void", vapor lock", air bubble, in one of the hoses to/from the heater core. When the coolant was being refilled enough "care" was not taken to avoid this.

    Toyota has not used a heater core water flow shutoff valve for many years now, going back to the early 90's..
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    It's called a "water control valve" and is cable operated, but wwest is right, it's not at the heater core, but in the engine bay.
  • finfin Member Posts: 594
    YES ! Thinking outside the box.... My focus was on the heater and controls but a defective t-stat, stuck open or other malfunction, could produce the same symptoms with all else working OK. It would also lower gas mileage slightly as the engine will never hold optimum operating temperature in winter. :)
  • wwestwwest Member Posts: 10,706
    You might want to check first and be sure the water control fully opens when you move the control to MAX heating. Valve is close to the firewall in one of the heater hoses.
  • mashoudmashoud Member Posts: 8
    Ah! Toyota Avalon and its bloody stupid heating and cooling system.
    My 2001 has perfect air conditioning but heating is garbage...went to dealer and they say these cars don't heat too well. Big problem is that the car heats sort of o.k on the drivers side, but passenger freezes.
    The dealer wanted $ 3000.00 to replace some flap that does not open or close close to the heater core. I think it is shameful of Toyota to not own up to this obvious bad engineering.

    Anyway, you say the heat does come but only upon recirculation. That tells me that the the heater core is not warming up enough for the fan to blow hot air over it but keeping stale air in does a bit of a trick.

    I would try and find the highest degree or "hottest" marked thermostat I can find and install it. Someone suggested it and I am certain that the thermostat is old and is stuck in an open position.

    I am always a bit ticked off when someone says " hey, the car is 13 years old"
    So what! I have a couple of cars that are 17 and 22 years old but apart from some routine parts like water pumps, alternator etc...I have never had to piss around with this dual air climate nonsense that Toyota suffers from. My 19 year old Audi never ever had heating or cooling problems. :blush:
  • cowboy88cowboy88 Member Posts: 4
    Thank you all so much!! I am re-reading the posts to see what the best course of action is. I made a mistake in my post. My wife's Avalon is a 1999 not a 1997.
    I was thnking about my truck for a moment. Sorry.
  • ronwuzhere2ronwuzhere2 Member Posts: 2
    my wifes 98 avalon is having trouble with the blower, it only works on low now. it was working intermittently but stopped doing that too. i tried replacing the blower relay did nothing. tried replacing the blower, nothing. just don't know what else to try. it has the automatic climate control, should i replace the controls? any ideas would help tremendously.
  • boxstackerboxstacker Member Posts: 1
    While making slow left turn in 08 Avalon my AC or heat turns off .. Dealer claims I accidently shut off ... this happens daily..and always at slow speed.
  • samanthavsamanthav Member Posts: 1
    I have a 96 avalon that i bought 6 yrs ago. I have never had any problems until now. My a/c had always almost overworked. Making my car very cold. now it only works maybe 2-3 days then gave out very little air for about a month.
    When i would drive it and make turns i could hear water swishing but could not tell where it was coming from.
    I wonder if anyone else has experienced this. If so, could you tell me short of taking it to a mechanic what was done to fix it.
  • manav82manav82 Member Posts: 16
    I own a 2007 Toyota Avalon and am having the following problem.

    When the car is stopped at a traffic light or in park and the AC is on, the RPMs will fluctuate. RPM will increase by 250 - 750 above idle every few seconds and then drop.

    The symptoms go away when the AC is turned off or set to MAX Cold Temp and High Fan. Fluctuations are greater when the AC fan is set to its lowest speed.

    Any ideas?

    Thanks,
  • wwestwwest Member Posts: 10,706
    SOP, the engine "idle" RPM is changed as the A/C compressor clutch cycles, engages and disengages due to refrigerant flow demand. Lower blower speeds, in general, make the system more efficient and thus longer cycles.
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