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Do you run your A/C 12 months of the year??

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859 views 35 replies 22 participants last post by  LeonardoDaBenz  
#1 ·
and yes I mean 12 months--even in the winter months (defined as snow time).

You should.

Got this on another forum--dealer said to run the a/c all the time, even in the winter with the heater on. And folks questioned the wisdom of this.

Why?

Other than keeping everything lubed up and seals from drying out, it helps to reduce the humidity and the resultant defrosting issues both outside AND inside the car.

Virtually every site I checked on (in an AI search-including car dealers) said to do this. I knew that I had to 'use it or lose it' so did run it sporadically over the winter but not often.

And keep it on 'outside air' NOT 'recirculate'. On recirc, you don't get rid of the humidity which in turn slows down the defrosting. In my CIvic, I had to scrape the inside of the windshield cuz it frosted over during the night the other day.

100% of the time. Never knew.
 
#12 ·
As an HVAC professional and a decent shade tree mechanic, I concur with the first post. The main cause of compressor leaks is front seal failure due to it drying up.

Additionally; the front defroster is far more effective with the compressor on because it is dehumidifying the air blowing across your windshield.
 
#13 ·
All my cars with AC have it on all year.
The only car I had issues with (two compressors at £800+ a pop) was an F10 3l BMW 5-Series. :mad: :mad: :mad:
 
#17 ·
Quite true but once you only use the heater, does the ac not turn off?

I tried today to run the ac with the heat (but not on defrost). It stayed off (it even said "ac off" in the display even though I pushed the button to turn it on). In my civic as the '55 is still sleeping.
 
#16 ·
#18 ·
Some of the imports (in context of the American market) allow you to turn the compressor on or off in defrost.
 
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#19 · (Edited)
LeonardoDaBenz said:
And keep it on 'outside air' NOT 'recirculate'. On recirc, you don't get rid of the humidity which in turn slows down the defrosting. In my CIvic, I had to scrape the inside of the windshield cuz it frosted over during the night the other day.
Click to expand...
That depends on where you are located. In somewhere cold and dry like Switzerland, outside air will work faster. London, Seattle, Malaysia, the air will be so humid, you'll be fighting the outside humidity. When you recirculate, it will still dehumidify the air (hence the water puddle under the car), just slower.
 
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#20 ·
if you turn on your windshield defroster, the AC compressor automatically comes on so i just use my defroster, but i agree yes, it should be run every once in a while. A/c helps dry out the moisture in defrost mode. if the compressor don't run, the windshield tends to fog up+
 
#21 ·
Hi,
with roof up, I always have it on.
With roof down, mostly off. Exept with hot weather, than it's on again...
In the SLK, it is making a kind of humming sound, I don't like. Have to look at it coming spring.
At out daily car, VW Golf tdi, we have it always on... just setting the temperature and it's always okay.
Allreay for more than 10 years, 270,000 km...
According a friend of mine, a head mechanic VW garage, it's better to keep it on.
 
#22 ·
Great to know! Summers here in Indiana can become hellishly hot, and I've been driving around with the top down and the air conditioner going full blast ever since I bought the car. People thought I was crazy. Now I can tell them they need to be doing the same thing.
 
#24 ·
I was surprised that the Mercedes air con works with the roof down (only discovered this after buying my R170) as I had assumed that it would be inhibited/ switched off with the roof open , as that is the case with my Mk 1 TT…..
But yes I do run the air con 24/7 as I read about the seals drying up if you don’t several years ago…..
 
A
#25 ·
contrary to many of you, I keep it 'off' most of the time. I'm based in Belgium, temperate maritime climate, cool and wet.
Only when there is a lot of humidity inside, I put it on. On warm days, we always drive open and out of principle, I find it insane to use the A/C in open air.
The main reason why I keep it 'off' is because it consumes more fuel and it makes the air too dry.
Don't know how much power it takes in the SLK, but on my Ford family wagon (diesel) I have measured it a few times during long distance rides. With the A/C 'on' the car consumption increased by almost 10%. On the SLK that would be like 0.6 to 0.9 liter every 100 km.
As a sidenote, on the SLK R171 'off' is when the control light goes red, which I find very confusing. It is the opposite of every other other car I drove in my entire life.
 
A
#32 ·
AC units in a lot of cars, particularly in winter, cycle the AC to dry the air so windows do not become covered in condensation. Running it in any mode in any season is going to be governed by the temperature control system. If the selected temperature is met the compressor shuts off and the rest of the system becomes an air handler.
 
#34 ·
RB,
Using is always better than standind stil...
As with everything and everyone...
Sitting the whole day in your chair is bad, 1 hour gym per day is 100% better...
Using your SLK every day is 👍👍 Park him for years in your garage without preparation is 👎👎
This is the same for your mechanical parts of your airco... 🤓
 
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