Morning

Just a quickie. I read somewhere that air conditioning should be used for 10 minutes about once a week or so to stop all the seals from drying out. Now this isn't a problem in my LS as the air conditioning is on all the time. What I was wondering is do I have to use the rear airconditioning as well to stop that going wrong or is it part of the front air conditioning so I don't have to bother?

I hope that made sense.

Many thanks.

Hi

Rear air con is separate and is in the boot behind the rear seat, if you look you can see the filter for the air purification system that is integral with it, you are dead right about having to "use it or loose it" You can just leave it on all the time if you want but 10mins a week should be enough.

Pete

Hi Pete

Many thanks for your reply. The front Aircon is on constantly but I will now put the rear air con on as I'm using it tomorrow. I would hat to think what work is involved replacing seals for the rear air con unit so I will switch the rear one on once a week.

Thanks again.

Jim.

Just to add to this - one keeps reading that if you turn on aircon your mpg goes from a fantastic 24 or so to three and a half, so I did some highly scientific empirical testing and turned off the rear aircon (usually on all the time).

Made not a gnats whisker difference to the mpg, so might as well have it huffing gloomily even when the rear sets are empty.

Interesting, I didn't realise that when car's have separately climate control in the rear that its actually a separate system..........or is it just Lexus that does that?

Yeah the mpg stuff is a bit silly, I think it only makes the large claimed difference when it's really hot and the aircon is working at full whack...........although that's exactly the time when you're not going to switch it off, so I wish all those eco morons would just shut up!

I tried this on my Nissan Micra driving shool car. It averages 38.4 MPG which isn't bad for constant start stop, turn in the road, reversing round corners etc. Switching the air con off I got the magic figure of, 38.4mpg. Turning it back on, 38.4. I think that the technology in making the compressors has improved so much that it makes almost no difference at all.

I always thought air con used a lot of fuel and took power frm the engine. I wonder how my new GS430 Sport Series II will be affected with and without using it.

does this apply to the mark 3 ls400 or not?

Hi

If your asking about wether you should use it or not then yes you should, the aircon is filled with gas and some oil, the oil helps the seals to keep their seal, if you leave it off for a long time the seals will dry out and the system will leak... its a use it or loose it job....

I have never noticed any difference in MPG in a modern car with the air con on or off, I think this harps back to the early days when the air con compressor was from a truck and took half the power of the engine just to turn it, most modern units are far more efficient and don't use much at all....

Pete

Thanks pete, im going to start using mine more, i try to use once a week as you say but usually forget. Is ther any benefit with a/c on when heating (as winters here !!) as it comes on every time i use the auto button whatever the temp?

thanks steve.

Steve

The air con will dehumidify the air so you definatly need it on in winter, especially if really cold or wet, you can clear the screen with cold air at startup as soon as the dehumidification starts as the dry air just clears it up... I have always left my aircon on all the time and never had any bother with any car I've had and its been loads....probably getting on for 15-20 with air con.

Pete

thanks again, will start leaving a/c on now. Sounds like it will help a lot in the winter with misty screens. Was always like most people afraid to use because of the increased mpg but i think the benefits outweigh a couple mpg if any.

steve

You won't even notice mate. A compressor obviously is always going to use a certain amount of power, but when you have so much on tap anyway it's not going to be noticeable. If we assume it takes 5hp, well 5 from just under 300 is a lot less of a drop than 5 from a tiny tin box that's only got 60 to start with!

in my ls400 it adds a distant hum to the sound of the engine which i dont like - and needs more pressure on the brake pedal due to higher revs

i like the sheer silence! but if needs must then it has to be done!

regards

miq

The only thing ive noticed with the a/c on is sometimes under acceleration and braking the revs seem to lurch a little if that makes sense, not a big issue but i assume its normal because the a/c side of things has to adjust depending on what revs you give the engine... made more sense in my head lol!!

steve