Air Conditioning Blowing Sand???

Cheers thanks, I can only hope.

What trek is at the top of your list?

We just started at Christmas ourselves.

Phil

Until ya change from recirculate to fresh and all the crap in the fresh side of the system end up in ya face. :-))

Not really true. Depends on the setup. I have never noticed it in ours. Even the bull dust doesn't come in.

You must have a bad setup in yours or there is something wrong with it. Are you saying that if its on recirculate and you are following someone in bull dust that when you swap it to fresh you get a cloud of dust in the car!! I would hate to take your car out bush. Check it put. You may have a problem. This shouldn't happen.

Phil

And we both have Toyotas. Shouldn't happen.

Mate,

You must have a unique setup then.
It is common for dust, etc. to be drawn in via the external vents.

Perhaps it is all in the interpretation of a "cloud of dust".
Try following someone else in a convoy on a dirt track.

Placing the intake onto recirculation allows the inside cabin to pressurize, thus limiting the amount of dust, etc. that enters.

Bill.

I have always wondered what people actually mean by the cabin being "pressurized". That implies all vents are closed and there is some kind of pumping action underway. My ears have never needed to po with any pressure in the cabin. It wouldn't work anyway because the two "exit" vents at the rear stay open all the time. They have a system that only allows air to exit the vehicle.

Like I said before it "does not happen to us". We close the vent as soon as it looks like dust etc. And keep it closed until well clear of the problem.

I just asked my wife and she said "Never". Not even in our kingswood or her mothers rally Mini. I do not understand. And of course we have driven in dust and smoke and have you ever driven into the rock and gravel cloud following a truck or large vehicle going the other way.

That's why I suggested there was a problem.

Also do people mean when they say the cabin gets pressurised whenever you switch to recycled air?

I meant to ask.

Also what do people mean when they say the cabin gets pressurised whenever you switch to recycled air?

A pressurised cabin simply means that the internal air pressure is at a higher level than the outside air, thus no outside air, or any contaminants that are present can enter.

This doesn't mean that all air vents are closed.

The same principal is applied in a vehicle that has a "non pressurised" enclosure, such as the tub in a utility vehicle, usually enclosed with a canopy.
Because the tub area is not at the same atmospheric pressure as the cabin area of a vehicle, it tends to suck in dust or sand. This occurs because the canopy enclosure is not "dust proof". The tailgate for instance is not sealed and when the vehicle is in motion, the canopy area may actually become negatively pressurised and because this enclosure is at a lower atmospheric level than the outside air, creates a kind of vacuum that sucks dirty air inside.

Open a forward facing window, or better still a roof vent and the internal pressure becomes higher than the outside air pressure, thus restricting, or even negating the ingres of dirt, bulldust, sand, or whatever other contaminants that may be present.

As a matter of interest, ARB has just released a roof vent that not only creates a positive air pressure within the canopy, but also includes a filtered inlet to stop dirty air from coming in through the vent and due to the higher internal pressure, reduces the ingress of dirty air through other openings in the canopy, such as the non weatherproofed tailgate area.
It's all basic science really.

The technical sheet for the ARB vent states that the air drawn in through the filtered vent, is equivalent to having the forward facing sliding window open 20mm or more, but with the addition of the filtered inlet.

P.S. I have no association with ARB. It just happens that I have recently purchased a vent for my vehicle after reading about it in the ARB 4X4 Action mag I receive as a customer.


Bill.

I just used Google to check the meaning of the word.

Wikipeda says
1. To maintain normal air pressure in (an enclosure, as an aircraft or submarine).
2. To put (gas or liquid) under a greater than normal pressure.
3. To design to resist pressure.
4. To pressure-cook.

For our cars I think the first meaning is applicable. To make sure the outside dusty or contaminated air does not enter the cabin. Like in some vehicle tunnels as well. But that is not actually pumping up or increasing the air pressure it is just maintaining it as it is and keeping the rubbish out.

Unfortunately a lot of people actually believe the pressure inside the car increases. No It does not. It is simply maintained.

That is why I think what people should be saying that the cabin is sealed.Well lets not discuss how water tight they are hey!!

I think I have taken up enough of your time. I am a mug for getting caught up in these pedantic debates and should just "shut my mouth". The English language is almost a thing of the past.Well all manner of spelling, grammar and punctuation is anyway. I cringe when I hear; "I have none". How can you possess something (in your hand) and then quantify it by saying that nothing is in my (hand) possession. And the word "seen". Ugh.

Have a good day and thanks for the chat.

Phil

Sandman,

I think you are confusing yourself.

A part of what you are saying is correct. If you can manage to have the air pressure inside the car to be greater than the air pressure outside the car, much of the dust that enters through the small openings, can be reduced. This pressure can be increased by putting in a roof top, forward facing air scoop, on top of a canopy for example. This, of coarse, brings with it the possibilty of dust entering through the scoop.

The idea that by putting your air into recirulation mode increases internal air pressure is wrong. For the pressure inside to be greater than the outside you would need more molecules of air (per given volume) inside than outside. In recirulation mode the fan sucks the air out of the cabin and then blows it back in. Overall there is no change in pressure in the cabin. To increase the internal pressure you would need feed extra outside air in by putting your A/C in fresh air mode. This again brings with thew issue of taking in dusty air.

And herein lies the problem. Do you bring fresh air in and take the risk that dust will enter thourgh the A/C or canopy scoop, or do you recirculate the air and take the risk that dust will enter thourgh other openings.

Every car will be different.


As to the original problem fo this thread. If you drive around madly so that sand is flying all over the place, some of this sand will eventually fall into the intake air vents. The only place it can go from there is into the interior cabin.

R

Thanks Rob. I was not getting anywhere.

Just sitting stationary on the road while a road train passes can throw up rubbish that can drop into a vent intake. Luckily we have a good system. Very little came out even when we switched to fresh air.

We were pleasantly surprised at how clean it stayed inside. 7000Kms and hardly any dust in the cabin.

Outside.Well that is another matter! It was beautifully covered in red dust etc. Magnificent.

Phil

Turn it on flat out and wait till it clears. Clean up afterwards.
Greg

Good on you Greg Hi mate

Try blocking all outlets first, bar one that matches the vacuum cleaner the best.

Turn the vacuum cleaner on and then the car fan on full.

Best of luck.