[vibzez]

Actually no Air conditioning system is 100% air tight. Neither is a car air tight and sealed. Their is no actual harm of rising CO2 in a vehicle if kept in recirculating mode, because the interiors actually do get fresh air from the numerous tiny holes and passages from:- 1. Tiny spaces near the doorhandles. 2.spaces between wiring coming from outside the cabin into the cabin. 3. Airconditioing system, which itself is not air tight. 4. Handbrake and gear leaver mounts. Little recirculation happens without out being aware of it, and is sufficient for balancing CO2 and restoring oxygen levels.

[megger]

Originally Posted by anupmathur

Split systems do not have any means to take in outside air.

That's not my understanding of split ACs. Split ACs have an indoor unit that you see on wall and outdoor unit is located outside or "split" as the name implies. They do have provision to get in fresh air.

[anupmathur]

Originally Posted by megger

have an indoor unit that you see on wall and outdoor unit is located outside .

...and only 2 pipes connecting them. One pipe (the one smaller in diamater) carries liquid refrigerant to the indoor unit and the other one takes the return gas back to the compressor in the outdoor unit.
No provision for air to be brought from outside to the inside.

[vnabhi]

But I read last year that some guys in a Santro died due to prolonged CO2 inhalation when they were stuck in the rains/floods at Mumbai last year. If cars were not air-tight, how did they die?

[anupmathur]

Possibly because they were not moving. The velocity of the car 'forces' some outside air in from the 'leakage' points.
You sure those chaps didn't drown?!! I thought it was like their central locking wouldn't let the doors open and they drowned in the rapidly rising water.

[tsk1979]

It was CO poisoning, not CO2 poisoning.
Many people sleeping in closed rooms(closed != airtight) with coal heaters on die due to CO poisoning. Reason? CO more readily combines with Hg in blood, as compared to O2. Therefore blood loses the capacity to take oxygen to brain.
So if you are in a room(not necessarily airtight), with a high CO percentage, you will die.

[cutdcrap]

My car is parked in not-so-dusty area. But whenever I put the blower on the fresh air mode, I get a puff of dirty air with twigs,etc.

So, when I start the car and roll down the windows I run blower on full speed at fresh air to get rid of them. I dont know how many of you expeience the same issue.

[vibzez]

Originally Posted by tsk1979

It was CO poisoning, not CO2 poisoning.
Many people sleeping in closed rooms(closed != airtight) with coal heaters on die due to CO poisoning. Reason? CO more readily combines with Hg in blood, as compared to O2. Therefore blood loses the capacity to take oxygen to brain.
So if you are in a room(not necessarily airtight), with a high CO percentage, you will die.

Yes The forscenic guys traced it to a leaky exhaust that filled the cabin with carbon monoxide. If your vehicle is in sound shape, the possibility of suffocating due to CO is non-existent.

[anupmathur]

Originally Posted by vibzez

Yes The forscenic guys traced it to a leaky exhaust that filled the cabin with carbon monoxide. If your vehicle is in sound shape, the possibility of suffocating due to CO is non-existent.

From where did exhaust get into the car?

[vibzez]

Originally Posted by anupmathur

From where did exhaust get into the car?

It happens when the insulation between the engine bay and the cabin is not good. I have personally experienced it in the Maruti van that is used in our factory. As it happens, the driver in charge of that loading vehicle did not take good care of the machine, and the exhaust fumes used to creep into the cabin from under the seat. I was shocked when I came across it.

[anupmathur]

Originally Posted by vibzez

It happens when the insulation between the engine bay and the cabin is not good.

Please remember that there are no exhaust gases 'hanging around' in the engine bay. These are being carried in a pipe, which only opens to the atmosphere at the very end. It would need a LOT of neglect to have exhaust gas coming out from anywhere other than the tail pipe!

[vibzez]

Originally Posted by anupmathur

Please remember that there are no exhaust gases 'hanging around' in the engine bay. These are being carried in a pipe, which only opens to the atmosphere at the very end. It would need a LOT of neglect to have exhaust gas coming out from anywhere other than the tail pipe!

The problem lies at the joint coupling where the exhaust pipe meets the engine block. If you go to any workshop and specifically enquire about it, you will get many examples of deteriorated exhaust joints. I have gone through one, and therefore brought it up.

[battada]

Guys,
Is there any FE drop if we run on fresh air mode continuously?

[vibzez]

Originally Posted by battada

Guys,
Is there any FE drop if we run on fresh air mode continuously?

Yes, because due to lower cooling caused by mixing of warm air from outside, the compressor is continuously on. While in recirculating mode the compressor cuts when a particular cooling temperature is reached. Thus less load on the engine for not having to work the compressor all the time.

[anupmathur]

Originally Posted by battada

Is there any FE drop if we run on fresh air mode continuously?

There is bound to be some, since the compressor will not be cutting off as often as on recirc. mode.
Cannot give you any numbers, far too many variables. Best is to try it out for yourself. I, for one, NEVER turn my AC flaps to take in outside air. Too much muck waiting there to come in and clog my car's evaporator!