Aircon Query

[sywy]

Why is it that every time (well nearly) I start the engine, the aircon goes into re-circulation mode? I've only recently noticed this, as it's been hot and it's recirculating the air inside the car. Can't say I've noticed it before a few weeks ago, but doesn't mean it wasn't happening before!! The aicon is not on 'AUTO', and currently set to blow at face level. All through winter, I usually have it set to feet and windscreen. Sometimes I have the aircon on, and sometimes I switch it off. Have I changed something?

[Sussex_Paul]

Just been out and checked mine.

On mine the recirculation light doesn't come on after I've started the engine in any of the air con settings - unless I actually press the button or push the pollen filter button.

Hope this helps

[Steve@Aberdeen]

If you hadn't said the aircon wasn't on auto I'd have said that's normal behaviour - mine is set to auto almost all the time and seems to get, and keep, the car comfortable for me whatever the weather. When I start it up in a warm spell, it goes straight into recirc and cools the interior down quite quickly - once cool, recirc goes off. The system also seems to get the right balance between face and feet for me. The only manual intervention is to demist, when I hit the demist button - 10-20 seconds later and I turn it off as the windows are clear.

Having said all that, it's a puzzle why recirc should come on automatically if auto is off.

[anchorman]

I have a pdf document that seems to suggest that some functions remain automatic even if "auto" is not selected, so;

temperature control will remain automatic is the distribution is over ridden

distribution (including recirc) will remain automatic if the fan speed is over ridden

but you can intervene all of those functions individually.

The pdf file shows a very complex array of mapping to provide what it calls a Neural Network Control which they say is the nearest possible match to a living organism in order to create the nearest input/output settings to that of the human brain.

Don't shoot the messanger, they obviously have a boffin that was given the heater as a project!!!

If I could only figure out how to attach the pdf I would show you.

Cheers

PS, mine has started recirculating most times I switch it on since the weather has warmed up. It did last September then stopped over the winter.

[sywy]

Thanks for the replies. I do think it's temp related, and as anchorman says, a sort of semi-automatic mode. I've decided to switch to full auto now.

[Manxrav]

Thanks for the replies. I do think it's temp related, and as anchorman says, a sort of semi-automatic mode. I've decided to switch to full auto now.

sywy, my T180 does exactly the same as yours.I thought I,d cocked up big time until I started reading this thread.

Cheers sywy I owe you one!!!!

Clare

[Steve@Aberdeen]

Once again, anchorman comes to the rescue!

I should have added that, whilst mine is in auto almost all the time, I often kill the cooler (aircon) when I know it's not needed (outside air is several degrees cooler than the inside setting and no excess humidity); it's to save a percent or so power absorbed by a running aircon unit. However, perhaps anchorman can tell me if the Rav4's system actually switches the cooler off when not needed - previous cars haven't done so but, from the above response, Totota may have moved intelligence on a step.

[anchorman]

Once again, anchorman comes to the rescue!

I should have added that, whilst mine is in auto almost all the time, I often kill the cooler (aircon) when I know it's not needed (outside air is several degrees cooler than the inside setting and no excess humidity); it's to save a percent or so power absorbed by a running aircon unit. However, perhaps anchorman can tell me if the Rav4's system actually switches the cooler off when not needed - previous cars haven't done so but, from the above response, Totota may have moved intelligence on a step.

Hi Steve

When in auto mode the air con will always default to on regardless of inside or outside temperature. By doing so it can always dehumidify the air (which is why it is engaged for demisting the windscreen) and can guarantee to maintain the inside temperature throughout any outside temperature changes. It will also monitor sunlight via the sensor on the dash and step up cooling while the sun shines (knowing the car acts like a greenhouse in the sun). Like you say, you can turn off the air con but pressing the auto button will always switch it back on again. It will not switch itself off at any time unless you are turning the demister off and the air con was not switched on previously.

Some other interesting bits and bobs.....

Dehumidified air also helps you feel less drowsy especially on humid days. Cooling the air works by the opposite principle of compressing a gas makes it hot. Refrigerant is forced through a needle valve and in doing so changes state from a compressed fluid to a low pressure gas. The temperature falls sharply and is then passed through a radiator which exchanges the cold with the humid air coming into the car. It condenses on the outside like a cold beer on a warm day and that is where the water comes from that is drained to the road under the car - it is just trickling off the radiator. All that water would have ended up in the atmosphere inside the car.

It is interesting to see the heater go through various changes in order to achieve the Neural Network Control. Just alter the temperature to the lowest setting and then back to the highest setting and you will see it engage the recirc at lower temperatures and also watch the distribution icons as they go through various settings to achieve the most comfortable climate.

All air coming into the car is filtered but in pollen removal mode, the air is forced back via the recirc mode and automatically directed through the face level vents for a period of 3 minutes then it reverts back to the previous setting.

The evaporator (the radiator like part that cools the air) is coated with a special resin that helps to deter bacteria and therefor minimise the risk of foul smells that are often associated with air conditioners.

Another interesting feature is that diesels only also have an electric heating element within the air conditioner. This is because the diesels are slower to warm up than the petrols so they are temporarily assisted by what can best be described as an electric fire!

The engine driven compressor will draw up to 5hp when working hard on a warm day.

Good int' it

[dave.m]

Anchorman,

Bloody awesome :o ,being a mechanical engineer myself, I suspect you done the extra couple of years that I did not. (ps Pink Floyd aint a heavy metal head banging group, they are very well spoken ex uni boys with degrees in things like architecture.) (well thirty years ago anyway).

Cheers,

Dave.

[anchorman]

Anchorman,

!Removed! awesome :o ,being a mechanical engineer myself, I suspect you done the extra couple of years that I did not. (ps Pink Floyd aint a heavy metal head banging group, they are very well spoken ex uni boys with degrees in things like architecture.) (well thirty years ago anyway).

Cheers,

Dave.

Dave

There is a section in the Toyota Publications called "New car features". It is a series of pdf files that give all the facts on how these things are put together and is well worth trawling through.

I did 29 years in the Motor Industry during which time I did all the City and Guilds stuff then went on for another six years to get a Level 5 HNC in Motor vehicle Engineering. I thent spent many years in Reaserch and Development on brakes and spent a lot of time in the test dept of various manufacturers. I never went to Toyota but I did go to Isuzu.

OK Pink Floyd wasn't too heavy but they were a little bit off the beaten track if you know what I mean.

Cheers

[Steve@Aberdeen]

The engine driven compressor will draw up to 5hp when working hard on a warm day.

Good int' it

Thanks - it's that 5bhp that prompts me to turn off the aircon when I sense it's not needed. It's right about dehumidified air keeping you more awake and a good reason to keep it on more often, but NE Scotland has aircon built-in for most of the year ;)

One extra point not so far mentioned is that, for those who leave the aircon off most of the time, it's good practice to switch it on for a few minutes every week or two to recirculate the refrigerant fluid - cuts down maintenance issues. The poor reliability reputation for vehicle aircon partly stems from drivers leaving it turned off for long periods, allowing seals to dry out.

[dave.m]

Good int' it

Anchorman,

Dont know if the climate control in your 4.3 is similar to the climate control in my 4.2, but i decided to try some of the scenarios you spoke about and got virtually the same results. To be honest its the first time Iv'e used the auto function. Very impressed.

Cheers,

Dave.

Ps, anyone know whats happened to the club store ?