AC issues and AC service

[Razor61]

I've seen differing opinions on what an 'AC service' or AC clean or whatever it's actually called includes and whether it is worth having done or is it a bit of a con?
I fixed my aircon leaks last year, O ring on pressure switch and the 'sight glass' slight leak. All good until a few months when during the hot weather I noticed all was not well and it wasn't cooling as it should.
Also a 'smell' in the car in the morning, severity depended on what the weather was like at the time and I had it on my agenda to get the AC looked at. 
Last year when the MOT carried in Lexus Bolton they mentioned some dye residue on the 'other' connector to the condenser which had been checked for leaks when I sorted the AC out a month or so earlier.
Residue from sorting out the AC I thought and wiped off the dye and thought nothing more about it until a few months ago.
Yesterday the car was in for it's MOT, passed with no advisories, and I asked for the AC to be looked at. The technician and myself looked at the car and I explained everything, when he looked at the 'other' connector to the condenser, which had the dye residue on it last year, he immediately said it's leaking from there and it's lost gas so it's sprung a leak since I the AC was sorted last time. This particular connector was the only one that wasn't replaced last time, in hindsight I should have done this one as well.
So, AC system discharged, new O ring fitted (I took a bag of assorted AC O rings with me in case they didn't have any), AC system recharged and checked for leaks. All good and AC is back as it should.
That's the AC issue done.
Lexus suggested an AC Service thing, I was a bit sceptical about this but they did me a 'deal' for the AC work and the AC service so I went ahead with it. I have seen a Car Care Nut YouTube video on this very subject where they pump foamy/foaming 'stuff' into the AC system via the condensate drain tube into the system round the evaporator etc and it drains out with all the crud or whatever, it looked really good and that's one of the reasons I went ahead with it.
The result......................car smells great now and the stale/old car smell has gone so I'm happy with that. How long this will last I don't know, time will tell though, and Lexus said the method described by the Car Care Nut is what they actually do.
It was worth having done in my opinion and I guess it should be done every few years to keep the system 'clean' or as clean as possible.

[NemesisUK]

Keep the a/c on at all times and the seals will keep lubricated and the air ducts won't get bacteria growing in them.

[Razor61]

31 minutes ago, NemesisUK said:

Keep the a/c on at all times and the seals will keep lubricated and the air ducts won't get bacteria growing in them.

I always have the AC on auto, can’t speak for the previous owners though.

[Razor61]

What seals do you mean?
From what I know about Automotive AC, I don’t think that using the AC all the time stops bacteria, due to how AC works moisture is created (condensate, hence the need for a drain) it’s this that can create the damp environment for mould and bacteria. Using AC all the time is better than only using it sporadically but if you don’t want any or more mould/bacteria then don’t use it at all. Switching off the AC and running it for 5-10 mins with fresh air flowing over and around the system to dry it all can help mitigate the mould and bacteria.

[Rabbers]

5 hours ago, Razor61 said:

… Switching off the AC and running it for 5-10 mins with fresh air flowing over and around the system to dry it all can help mitigate the mould and bacteria.

I’ve been doing that periodically for years - probably having got the tip from some motoring magazine - and I had frankly forgotten the reason why, so thanks for reminding me. 

[NemesisUK]

15 hours ago, Razor61 said:

Switching off the AC and running it for 5-10 mins with fresh air flowing over and around the system to dry it all can help mitigate the mould and bacteria.

As the a/c second main function is to dehumidify the incoming air I don't see how switching it off and allowing 'unconditioned' air through the system can dry it any better?

I never switch off the a/c and in all the years I've had cars with a/c I have never suffered from foul smells (well, not from the a/c anyway 😉 )

[DavidCM]

I would guess chilled air in the ducts would condense on a hot day and this could cause a mouldy smell.

Blasting the chilled air out of the system would ensure the air in the ducts is at ambient temperature and therefore won't leave condensate to go mouldy.

[NemesisUK]

17 minutes ago, DavidCM said:

I would guess chilled air in the ducts would condense on a hot day and this could cause a mouldy smell.

 

The chilled air is dehumidified, so contains less moisture than ambient air and on a hot day surely any moisture would evaporate rather than condense? In fact driving ambient air into the chilled duct work is likely to do just that, the moisture in the ambient air will condense on the colder ductwork surfaces?

[DavidCM]

1 minute ago, NemesisUK said:

The chilled air is dehumidified, so contains less moisture than ambient air and on a hot day surely any moisture would evaporate rather than condense? In fact driving ambient air into the chilled duct work is likely to do just that, the moisture in the ambient air will condense on the colder ductwork surfaces?

All correct Peter.However,once sufficient ambient air has gone through, temperatures will equalise to the surface and air, therefore no condensation will occur.I guess the ducting is far too thin for interstitial condensation to occur(as can happen in larger structures such as buildings)

[NemesisUK]

There must be more to it, as in other factors involved, as I have never experienced this problem. Just lucky perhaps?

[DavidCM]

18 minutes ago, NemesisUK said:

There must be more to it, as in other factors involved, as I have never experienced this problem. Just lucky perhaps?

Quite possible.Either way,both approaches give a similar result.

[Razor61]

Just to clarify something, the ‘smell’ I mentioned wasn’t a bad mouldy smell. It was more of a humid taste, if that makes sense. This has now gone and the ‘old car smell’ has gone, maybe because the AC treatment has acted like a giant air freshener or it’s done it’s job fantastically well.
Air conditioning does just that, conditions the air, heats when needed, cools when needed, dehumidifies when needed, controls the flow of air from outside or inside and maybe humidifies.
When it dehumidifies the moisture has to go somewhere, it goes into some kind of tray then drains out under the car. So there is moisture/water in the ‘system’ and around the evap coils (I think that’s what they are called) and it drains into the tray thing. Turning the AC off stops the moisture accumulating and then the ‘normal’ air flow going over the coils etc helps dry everything, that’s how I understand it.

I was told by an Automotive AC guy that when people don’t use their AC for a long while then suddenly start using it, the moisture goes into the tray thing and reacts with the dried residue and causes the smell. Also residue on the evap coils probably.

[Rabbers]

Having pondered this thread in the course of a long and boring drive earlier today, I came to the conclusion that it was leading me to overthink an issue which may not even exist.

Like Peter, I have not experienced bad smells from the car AC, not in any Lexus, and none I particularly recall in earlier cars I had.  I keep the AC on permanently - with closed windows, of course - summer and winter, and regardless of the outside temperature.   I turn it off only (a) when the sunroof is open, (b) if the cabin needs ventilating after the car has stood in hot sun, and (c) periodically - not routinely, but whenever the fancy takes me - for a few minutes with the fan at max in order to let fresh air through the system as per a habit of obscure origin I acquired years ago, maybe from a BMW owner’s manual.  

When I turn the AC back on in cases (a) and (b), the impression I have is simply of a system recommencing its job of conditioning the air satisfactorily and wholly unremarkably, whereas in case (c) I have sometimes noted, though not on any basis beyond a very quick and fleeting thought, that the system is now providing air that I would describe, at the risk of splitting hairs, as “crisper” rather than “cleaner” insofar as the latter term would imply the earlier presence of a smell or other form of irritant when there wasn’t one. This I naturally find to be a good thing, and I would find it even better and more pleasing were I able to objectively confirm that my having turned off the AC was responsible for what I could only guess to have been a temporary reduction of the density of the moulds and bacteria populating my system to levels that are, and based on past experIence, seem likely to remain, sensorially undetectable.
 

[Malc1]

.................. call me Old Fashioned I guess BUT I do actually regularly open windows and occasionally, but rarely the sunroof too  .........  the aircon is possibly a vestigial item in my Ls400 repertoire 

Malc

[Razor61]

We have a 2010 IS250 as well which was in for its service a few weeks ago, the AC bacteria levels were measured and were very high, they recommended the AC service thing and I said I would think about it. I can’t remember the figures but it was way into the ‘red’ zone. It’s back in for its MOT in a couple of weeks so will have it done. No smells or anything in the car, if the Lexus dealer tells me the bacteria levels are very high and above the acceptable levels then I have to believe them and do something about it.

[Malc1]

2 hours ago, Razor61 said:

We have a 2010 IS250 as well which was in for its service a few weeks ago, the AC bacteria levels were measured and were very high, they recommended the AC service thing and I said I would think about it. I can’t remember the figures but it was way into the ‘red’ zone. It’s back in for its MOT in a couple of weeks so will have it done. No smells or anything in the car, if the Lexus dealer tells me the bacteria levels are very high and above the acceptable levels then I have to believe them and do something about it.

I just wonder what any other AC specialist or Bacteria in Cars Specialist might say ?

You're very trusting of your Main Dealer  🤫    what's the cost likely to be ?

Malc

[shanra]

A good link all about A/C http://www.airconditioningforcars.co.uk/

[Razor61]

1 hour ago, shanra said:

A good link all about A/C http://www.airconditioningforcars.co.uk/

A very good link and explains things better than I did🙂

[Razor61]

3 hours ago, Malc1 said:

You're very trusting of your Main Dealer  🤫    what's the cost likely to be ?

Yep, I trust the service guys at Lexus Bolton. As for the cost, I'm not 100% sure but I think it's £175 for a full AC service - checking the AC in general - more gas if needed - replace any O rings leaking and the Anti- Bac treatment.