To A/C or not to A/C

Djwbiker · February 7, 2021

I'm a bit old skool my first car with a/c was a Ford Granda c1986 so have only really put the a/c unit on when I need the cooling. Reading a recent post on the GS450 page got me thinking about my RX400h should I leave the a/c switched on all the time and just set the temp required?, does this have a noticeable detriment to fuel consumption as it did in my Granada days?

thanks chaps

katabrontes · February 7, 2021

I leave mine on all the time. The difference in mpg is barely measurable and it ensures the system keeps fully lubricated and the seals don't dry out.

NemesisUK · February 7, 2021

I leave my a/c on permanently, summer it cools, winter it dries.

In fact I have my climate controls all set to automatic, I just set the temp and let the car sort it out to the best effect.

Herbie · February 7, 2021

These cars don't just have A/C, they have climate control, the whole idea of which is as Peter says above, you set the temperature you want and the car maintains it for you. It is designed to be on continuously.

ColinBarber · February 7, 2021

1 hour ago, Djwbiker said:

does this have a noticeable detriment to fuel consumption as it did in my Granada days?

The AC system on the 400h is much more efficient. It is electrically operated via a motor, rather than mechanically driven by the engine, and the motor speed is electronically controlled so it only runs at a speed needed, not any faster.

I'd recommend using it during winter. It drys the air so you get less condensation and reduces any risk of mould etc. You can also use the recycle function without the inside becoming like a rain forest so you can keep diesel fumes out if you get stuck behind one.

If you don't want to use it then you should run it for 5 or 10 minutes every few weeks just to keep everything within the system lubricated correctly.

impero · February 7, 2021

1 hour ago, NemesisUK said:

I leave my a/c on permanently, summer it cools, winter it dries.

In fact I have my climate controls all set to automatic, I just set the temp and let the car sort it out to the best effect.

I do the same.

Leaving climate controlling system on automatic all the time, keeps the system prepared all the time.

So yeah, i suggest you do the same

Ala Larj · February 7, 2021

Ac on. I actually find it most useful in the colder months to keep condensation at bay.

Linas.P · February 7, 2021

Not much more to add... AC should be kept on, not only to control your "climate", but as well to keep the system itself lubricated and seals from drying out. Not doing so could damage the system over time and as well cause bacterial growth in condenser etc. When that starts is stinks quite bad and quite difficult to clean it off - there are treatments but you may need to do it few times to fully kill it.

PCM · February 8, 2021

Sound like a yes then...

Agree - good in Summer and good in Winter.

rich1068 · February 8, 2021

13 hours ago, ColinBarber said:

You can also use the recycle function without the inside becoming like a rain forest so you can keep diesel fumes out if you get stuck behind one.

Never quick enough with this! Usually behind some VAG soot monster, they set off, cloud of black smoke, I'm left choking and dithering for where the button is.

Djwbiker · February 8, 2021

Thank you all for the advice I will put a/c and have to eat humble pie with the misses as I've always moaned when she left the a/c on!!

many thanks

steve2006 · February 8, 2021

Could I add a couple of points, replace the cabin filter at regular intervals and use an air conditioning aerosol cleaner yearly. These help keep the system efficient and bacteria free respectively.

Linas.P · February 8, 2021

5 hours ago, rich1068 said:

Never quick enough with this! Usually behind some VAG soot monster, they set off, cloud of black smoke, I'm left choking and dithering for where the button is.

The saddest thing is when you think you are behind Lexus and then black smoke puffs out and you realise it was IS220d 😪

But mane is always on AC + re-circulation, because otherwise car becomes like a gas chamber.

NemesisUK · February 8, 2021

I leave the recirc on auto and the pollution sensor switches modes as required. Plus in summer it switches automatically to recirc to speed up cooling the cabin and in winter to warm the cabin, switching back to fresh air when heating/cooling has achieved the desired cabin temps.

Damned clever this Lexus climate control.. Neural network controlled -

"This control is capable of performing complex control by artificially simulating the information processing method of the nervous system of living organisms in order to establish a complex input/output relationship similar to that of a human brain. " 🤓

Herbie · February 8, 2021

^^^^^^^^This.

I've never understood people who buy cars with stuff like this in and then think they know better than the computers. Just let it do it's thing that it was designed to do and you get the best out of it.