cabin/pollen filters

You're correct in your assumption of what they do and interchangeability.

"Robert" wrote

What kind of smells do you want to remove? Bear in mind that the worst smells develop on the aircon heat exchanger and the cabin filter is in the wrong place to do anything about it.

Buying a carbon one is definitely an advantage to the manufacturer.

Is a filter even necessary? Once upon a time nobody bothered.

Ah, that only happens if you're daft enough to buy a car fitted with AC and then not use the AC because you're too cheap to understand that running the AC is less expensive and quieter than having the window open at anything other than walking pace.

If you run the a/c regularly you don't get the nasty smells.

If you don't use your A/C, then you're going to get a far bigger bill from fixing it than you ever would from using it.

Is it an option?

Please explain your reasoning.

If you think someone is "daft" not to use it, wouldn't you consider them even dafter if they went and fixed it when it broke?

True!

Then you could use the system without them. Personally I find it nice not getting dust in my eyes. ;-)

Put it this way, if I have the choice between two identical cars to buy secondhand, both the same, but one has working a/c. There's only one I'm going to buy unless I can chip the price of the A/C repair off the other one - and I'm not talking about a £30 regas, more like £350-500.

I doubt very much I'm the only person who thinks like this.

Obviously. Though, while aircon is nice to have, it's not something I would consider so essential to be worth fixing on a discounted purchase.

Now, failure to work after extended non-use is understood but you also made a statement to the effect that smell has something to do with light use. I asked you to explain but you haven't come back. (It doesn't make sense at face value, btw.)

Interesting that when Googling for "aircon smell" every man and his old wife seem to have a different solution. One suggestion, to dry it out by switching it off some time before stopping the car and not leaving it in recirc, seems the most logical.

In even moderately humid conditions, water will condense on the evaporator. (That's why you see puddles under cars with A/C.) If the system is only used infrequently, for short periods of time, the condensed water doesn't dry out and encourages bacterial growth on the outside of the evaporator. This is what smells. It actually makes perfect sense, and IME, does happen.

Once you've got it, it's also really difficult to get rid of.

The reason being that it gives the evaporator a chance to dry out before you switch off.

Chris

It dries out when switched off while the car is running. See below. Therefore the above only makes "perfect" sense if "infrequent" means the car is used for mainly short journeys - ie, it is the large number of airflow interruptions causing the problem and has nothing to do with light usage over a high mileage.

Indeed.

It has nothing to do with mileage, or the length of journeys, and everything to do with the amount of time the vehicle is left unused between journeys.

Chris

...because...?

The smell is caused by bacteria build up in the heat exchanger. And that takes time. I find switching off the AC but leaving the fan running about a mile from home stops the smell.

... the longer the vehicle is left unused with the evaporator wet, the greater the chance of bacterial growth.

Consider two situations; firstly, a car which does one 500 mile trip once a week. Secondly, a car which does one 10 mile journey a day. It would be more likely that the car in the first situation would suffer from the "smelly A/C" problem.

I ran a Focus for 10 years. Whilst I was working, I had a 14 mile each way commute. When I retired, I resolved to try to cut down on multiple short trips, and walk instead. The car is often unused for between 3 and

After a couple of months, the A/C started to smell. I started turning it off before journey's end, and over time the smell disappeared.

Chris

I had hoped that with a statement like the one you made above you did so with technical background. Your scenerio only holds on the assumption that the evaporator is wet when parked and it sits wet between journeys (what, it takes more than 6 days to dry out?). So, we seem to return to the frequency of it parked wet being the issue and little to do with the length of parked up period. What you said even suggested that a dry system would develop a smell.

Why? It's not a "technical" situation.

Common sense is all that's needed here...

But it will be if the A/C is running when the engine is switched off, and conditions are humid enough. What do you think the pools of water are that appear under a car in such conditions?

(Yawn)

The time it takes to dry out is not relevant; the length of time it takes for bacterial growth to happen is.

Oh, and yes, it could easily take 6 days or more for an evaporator to dry out in the right (or wrong!) conditions.

How?

Chris

My £0.02:

A/C is a creature comfort, hence it's importance is very much a matter of personal opinion. Speaking for myself, I find it's a marvellous feature and offers enormous benefits in terms of comfot & convenience in exchange for a small (not significant IME) loss of economy. I'd be reluctant to buy another car without it and I certainly value it more than electric windows, central locking or even PAS.

A pollen filter is very much the same; a convenience feature, not strictly necessary, but very nice to have especially for hayfever sufferers such as myself where, combined with the above feature, it really does make a difference.

The reason I've heard that the A/C breaks down with lack of use is because the seals become starved of lubrication and contract, thus allowing the refrigerant to escape. I've run an A/C equipped car for several years straight without ever needing so much as a regas, simply by making sure it's switched on for a couple of minutes at least once a week, so it's not exactly costly to maintain. However, *if* for whatever reason you don't like A/C, it will do no harm whatsoever to simply ignore it's existence and continue to do so after it ceases to function. ;-)

Stu

Oh, but it is.

Even statements offering "common sense" need background to show how you got there and the reasoning shouldn't need to be teased out of you.

As the paragraph stands it's another to file under "old wives' tales". Unless you want to add the various assumptions discussed.

OK. So where's the background to that statement?

From previously:

"I ran a Focus for 10 years. Whilst I was working, I had a 14 mile each way commute. When I retired, I resolved to try to cut down on multiple short trips, and walk instead. The car is often unused for between 3 and

After a couple of months, the A/C started to smell. I started turning it off before journey's end, and over time the smell disappeared."

That's not an assumption. It happened. To me.

Review the archives; many others have had the same problem. and resolved it with the same solution.

Chris