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Discussion Starter · #1 ·
I have had my new car which comes with air con all summer and so have been enjoying the delights of cool cool air. However, Iím confused as to what to do during the winter.

I understand air con cools, but during the winter you want warm air, so you shouldnít have any need to have the air con on, yeah? But then the air con drys the air out which is great for keeping the windows mist free.

In this damp weather I am finding my windows really condensed up and have found putting the air con on clears them instantly, and I can change the temperature to be hot too which makes it nice and comfy for me. But is this right? What happens when you put the air con on with a high temperature ñ does it still come on? Does the compressor etc, run the other way round? Will it cause any damage?

I realise this may be a completely stupid question!
 

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It won't do it any harm, in fact it's better to run it instead of leaving it idle for months. Air Conditioning is meant to do what it says on the tin, i.e. improve the condition of the air, (that means dehumidify, not just Cool).
 

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As has already been said, you should definitely use the air-con over the winter months as the seals in the system rely on the refrigerant gas to lubricate them......
No air-con use can cause the seals to dry-out and cause gas leaks, so most car makers recommend running the air-con system for a few minutes at least once a week....
The ease with which air-con clears misted-up windows in the winter months when it is wet is a real boon, wouldn't be without a car now that didn't have air-con, its just as useful in the winter months as it is in the hot summer ones IMHO.......
 

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Discussion Starter · #5 ·
Cool!! (arf!)

Thanks for the replies. I glad that clears that up. So air con isn't just for keeping cool.

Chhers.
 

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Just had a thought, most air-con systems have a safety-feature that prevents the compressor from working at low ambient temperatures (theres a danger the system could freeze-up) so below about 5 degrees C car air-con systems wont work.....
Be aware of that and come the depths of winter you won't think the thing has broken!......

;)
 

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Nessy said:
Just had a thought, most air-con systems have a safety-feature that prevents the compressor from working at low ambient temperatures (theres a danger the system could freeze-up) so below about 5 degrees C car air-con systems wont work.....
Be aware of that and come the depths of winter you won't think the thing has broken!......

;)
Air conditioning works by physically freezing the air and filtering it, so theoretically air temperature should be of no concern.
 

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ianbott said:
Air conditioning works by physically freezing the air and filtering it, so theoretically air temperature should be of no concern.
The climate control/air con system in my A4 does not operate below 5 degrees Celsius, and the handbook states what I've posted.

;)
 

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justbuggin said:
Yep, you need a higher ambient temp to evaporate the refrigerant & give the cooling effect.
Well you learn something new every day, when you say evaporate the refrigerant, what do you mean? surely the refrifgerant does not get evaporated? I know the moisture out of the air evaporates like it does in a fridge on the pump. and also you get the puddles under a car sometimes when working hard in the summer.
 

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ianbott said:
Well you learn something new every day, when you say evaporate the refrigerant, what do you mean? surely the refrifgerant does not get evaporated? I know the moisture out of the air evaporates like it does in a fridge on the pump. and also you get the puddles under a car sometimes when working hard in the summer.
There is an evaporator unit in every air-conditioning system. As the refrigerant is compressed by the air-con pump it travells along the pipes and is forced in to a sealed evaporator which causes a rapid cooling. - Liquid gas converting into gas. This can be seen on a gas BBQ when you are really going some - frost and condensation will form around the gas canister. As this happens - the surrounding metal of the evaporator cools also. The passing air flows through the evaporator unit - like a radiator and cools the air. Et Voila! :D
 

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Dub Man said:
There is an evaporator unit in every air-conditioning system. As the refrigerant is compressed by the air-con pump it travells along the pipes and is forced in to a sealed evaporator which causes a rapid cooling
Spot on. Just in case it helps to clarify it, the key is the "sealed evaporator". It's not evaporating into the air and being lost. Liquid refrigerant evaporates and turns into cold gas (used to cool the air coming into the car). That gas is kept in the system though.. It then goes to the compressor (which pressurises it and heats it up in the process), and finally condenses back into a liquid as it cools in the radiator at the front of the car. It's then ready to do the whole thing again.

I think the 5 degree thing is mainly to make sure that the evaporator can't ever get down to 0 degrees. If it did, then all the water condensing out of the air would freeze and completely block up the evaporator, so that air couldn't get through any more...

And in answer to the original poster, it doesn't run in reverse when you want heat. There's a conventional heater (just like in a car without air con) after the fridge part. So the air gets cooled (which makes moisture condense and drip out in a puddle), then it's heated up so you get warm, dry air perfect for demisting.
 

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AJB said:
Spot on. Just in case it helps to clarify it, the key is the "sealed evaporator". It's not evaporating into the air and being lost. Liquid refrigerant evaporates and turns into cold gas (used to cool the air coming into the car). That gas it kept in the system though.. It then goes to the compressor (which pressurises it and heats it up in the process), and finally condenses back into a liquid at it cools in the radiator at the front of the car. It's then ready to do the whole thing again.

I think the 5 degree thing is mainly to make sure that the evaporator can't ever get down to 0 degrees. If it did, then all the water condensing out of the air would freeze and completely block up the evaporator, so that air couldn't get through any more...

And in answer to the original poster, it doesn't run in reverse when you want heat. There's a conventional heater (just like in a car without air con) after the fridge part. So the air gets cooled (which makes moisture condense and drip out in a puddle), then it's heated up so you get warm, dry air perfect for demisting.
Well this thread has totally wised me up to how A/C actually works, thanks.
I thought the A/C radiator was for the cabin air to pass through and to be cooled. and didn't realise it cools the regerant.
 
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