Does the A/C need exercise?

[mikhail]

My 99 NB TDI came with air conditioning, like it or not. I know it's odd, but I never use it. Recently someone told me to "exercise" the A/C at least once a week to keep it from going belly up. Any truth to that? When I sell the car, I'd like to be able to demo cold A/C.

M

 

[Danny Boy]

I recall one of the many things I read in my youth this exact claim. I used to disect the transportation section of the newspaper, in order to learn more about proper maintenance of automobiles.

The air conditioning system is a pressurized system with coolant and oil. Running the AC engages the compressor to circulate fluid and keep the components clean and clear. The switch for the AC is actually a compressor switch, engaging the pressurization of the system. The temperature variant (between internal coolant core and the external heat exchanger may lead to condensation (which may equal corrosion). Most all systems have dehumidifyers. Of course these are stationary desicant tubes requiring flow in order to remove moisture.

Unless someone else out there is an AC expert, I recall reading an AC should be used atleast weekly for even a short stint, in order to maintain the internal system. This is more of an issue in the winter, when these systems are typically not even used!

 

[mikhail]

Thanks, Danny Boy. Once a week, I'll let me TDI idle for a few minutes in the driveway with both windows down, me out of the car and the A/C going full blast.

 

[MITBeta]

The A/C system also has a number of seals which will dry out if the system is not used for long periods of time. This is often how coolant leaks during the winter when no one uses their A/C.

 

[Vhunter]

I think it would be a good idea to make sure that you do exercise the A/C, to keep the seals lubed. "Some" cars are programmed to spin the compressor over a few turns after the car is started, just to keep the A/C in shape. If you notice on some GM machines you have to go thru the A/C setting to get to any other setting after it is in the OFF mode..

FYI: If you drive with the defroster turned on, the A/C pump will work, even if it is very cold outside. The reason for the A/C to run with defrost, is to de-humidify the air blowing on the windows, so the dry air will be removing the condensation.

With Defrost on, it will even run with the temp. control in the WARM end of the adjustment. This is where it should be anyway to clear off your windows. Warmer air can hold more water than cold air after all.. and if it is humid outside, you don't want to chill your window to the point that you will start to condense water on the OUTside of the window either!

Drive ON!

 

[Cosmic Green]

mikhail, I'm convinced that using the A/C regularly will keep the system healthy. I purchased a 1993 Escort brand new, and I used the A/C constantly through the summer, and used it to help defogging in the spring and fall. The car (a co-worker owns it now) has 485,000km on it, and the A/C still works! My 99.5 Jetta has 180,000km on it, and I haven't had any trouble with that A/C system yet either.

 

[dieseldorf]

this certainly is a valid point and I do practice running the AC every week on all vehicles whether I need cooling/de humidfying or not.

My concern: Most cars, if not all, would have a protective lock out so the compressor cannot operate below 38F or whatever the threshold is. So, for people in really cold climates, how can we run the AC compressor weekly if it won't turn engage??

I know someone will have the answer...

 

[mikhail]

Interesting posts everybody. Looks like the A/C is one of those mechanical contraptions that mimic human anatomy. Don't use it, it goes away . . .

M

 

[weedeater]

There are very few A/C systems that have the temperature sensors required to stop the compressor from turning. What usually happens in cold weather is that the pressures in the system get either to low (save the compressor from a lack of coolant) or to high (save the compressor from blowing up).

In our case, it would come on in cold weather, but shut off rather quickly as the presssures build up.

 

[chopchop]

Refrigerant-circuit seals rely on a swelling effect to seal properly, and so the system must be used regularly to for the seals to work longer-term. Also, the lube oil in the refrigerant needs to be circulated.

The general rule I was given years ago was to ensure that a/c systems are "worked" at least once every couple of weeks all year round for a minimum of 10 minutes or so, and that seems to have been fine for mine.

 

[golfstream]

I could be wrong so I'll have to check the manual, but I think with our cars and todays cars in general, whenever you use the defroster you're using the AC... or, at least the part that needs to be "exercised."

Mel

 

[choij1]

Folks, take a look at this one. http://forums.tdiclub.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=22&t=000494

 

[dieseldorf]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Mel Knott:
whenever you use the defroster you're using the AC...
Mel<HR></BLOCKQUOTE>

Mel, I don't think this is the case with VWs. It is true for GMs and others.

Based upon the comment by DBW in that other thread, it does not sound like the compressor comes on when its below ~40F.

 

[Stainlessillusion]

The AC system SHOULD be used each time you use the defroster. In VW and most German cars, this requires you to press the AC button while in Defrost mode. In most American cars, the AC system automatically functions when the selector is in the Defrost setting. By using the AC, the moisture will be removed from the air and will defrost much more quickly.
It is true that the AC system needs to be exercised all year. It not only helps the seals in the lines but also the lip seal on the compressor itself where the pulley turns. Unlike a freezer or home AC which is completely sealed, the Car AC has a shaft that must exit the system and be turned via the belts.
-Brandon

 

[Al Kane]

Older R12 A/C systems use mineral oils for lubrication, and the seals rely on the mineral oil to help them swell and seal tightly against leaks. Occasional use is recommended to prevent leaks.

Newer A/C systems that use R134a have polyalkylene glycol as the lubricant, and a different elastomeric seal material that does not swell. It is not necessary to occasionally run R134a systems to prevent leaks, though there is certainly no harm in doing so.

 

[VelvetFoot]

That's good to know Al.
I have a tendency not to use mine at all.