'Blowing Moisture Out of A/C System'?

[Mr_Joe]

Yes, the wife thinks I'm full of it. For 20+ years I've always tried to blow the moisture out of the vehicle a/c system before shutting down. When about 3-5 min before parking(time based on temps & vehicle occupants) I turn off the A/C system but leave the fan blow in the cool/cold setting. After a bit you have the outside air temp blowing through the vents.

When done properly there is hardly ever any 'a/c drip' after parking. Doing this I have had very good luck with a/c systems. My 2003 GMC truck is still blowing very cold air. The other & past vehicles have averaged well too.

I know many shut off with the a/c still on, also with some the a/c compressor is activated in any 'defrost' mode.

Has anyone out there ever heard of such operation of the air conditioning system? Maybe I'm the only one on this?

If nothing else this is a tip for those so inclined. Then you have to get the other drivers on board.

 

[AandPDan]

I do it too.

I'm not worried about the drip, it's more to keep stuff from growing in the evaporator housing.

 

[fdcg27]

All you're doing is getting the moisture off the coil.
The drip after shutdown is of no concern.
You aren't getting moisture out of the refrigerant system, since it's a closed system and should have been vacumed before it was filled to eliminate any moisture.
This is an unecessary although harmless gesture.
WRT the life of an AC system, our 1997 Aerostar still blew cold after thirteen years and 176K with no service, our 1997 Accord still blows cold after fifteen years, 205K and no service, although our '99 Accord is cycling the compressor more than it should so may need a top-off of 134a.
The key to long AC life is to use it. This keeps all of the seals fresh.

 

[Chris142]

doing what you do helps eliminate fungus from growing on the evap and stinking

 

[Mr_Joe]

I am not worried about the drip at all, that is just my indicator that less moisture is present. It is the internals I'm trying to dry up.

I also agree with using the system periodically to possibly 'lube' the seals.

 

[heyu]

Originally Posted By: Chris142
doing what you do helps eliminate fungus from growing on the evap and stinking


Every car that has A/C has a drain tube in the bottom of the firewall ,,That can get blocked because from dirt in the windshield wiper cowl area,,,You have to blow compressed air up the tube to unclog it ,,and then open your hood and pour bleach in the top cowl area along with water from a garden hose and let it all drain down the drain tube

 

[Eddie]

A good idea that I've always done. That being turning off the AC compressor 2or 3 minutes before shutting off the blower.

 

[xxch4osxx]

I do it to reduce the moisture left sitting on the evap coil and like others said, reduce the smell.

 

[Rick in PA]

I try to do this (when I remember to) mainly to keep mold & mildew from growing in the evaporator.

 

[HTSS_TR]

I turned off A/C about 20-30 seconds before parking. When I go home I turned off A/C when I was on my block about 10-12 houses from my home. To someplace else such as shopping, I turned off A/C when I was in parking lot looking for parking space.

 

[GMBoy]

Some later models have an "afterblow" feature to do this for you after you park the car. It will run the fan for 10-15 seconds or so.

 

[antonmnster]

You'd have to run the fan for a long time to actually dry out the box. There's always going to be some moisture, and it takes almost none for mildew to grow. So I don't think mold/mildew is going to be prevented.

And the system, if it works, has no moisture in it. That's why it has a desiccant; if there were moisture in the system would form acids and die.

I push the snowflake button on in April and leave it on until October. I don't feel like I'm abusing anything.

 

[Mr_Joe]

Nice to see a few have at least 'perceived' value in the practice. Yes, maybe only anecdotal evidence at best, but I will carry on with the procedure.

 

[punisher]

If it was worthless, FoMoCo wouldn't have come up with a delayed fan module to install in order to cut down mold growth/smells from evap cores/cases. The module would run the fan on low for a few minutes after shutdown to get excess moisture out of the evap case. Sometimes the foam/weatherseals make yummy food for certains strains of fungi.

As far as pouring bleach and water down your cowl vent.....just no. The cowl drain has nothing to do with the evap drain.

 

[SteveSRT8]

^^^It will work on some cars as it is a straight shot into the evap box. Just depends on your configuration.

As to increasing longevity I doubt it, but if it makes you feel good continue. I have one van in my fleet that is an 04 with 400k miles on it with all original AC intact and operating well.

Its never had any special treatment, mostly run hard and put up wet!

 

[mechtech2]

So no AC for 3-5 minutes when you need it?
That's a LONG time to sweat for nothing!
Hardly a good solution .

 

[CROWNVIC4LIFE]

Originally Posted By: Mr_Joe
Yes, the wife thinks I'm full of it. For 20+ years I've always tried to blow the moisture out of the vehicle a/c system before shutting down. When about 3-5 min before parking(time based on temps & vehicle occupants) I turn off the A/C system but leave the fan blow in the cool/cold setting. After a bit you have the outside air temp blowing through the vents.


Since my first car that had factory air [1967 Impala] I never shut the a/c off in any of my cars all year long..I always have a large pool of water under my cars due to the super high jungle humidity..I keep my cars 8-10 years and between and 200-300K miles..I have zero smell,zero mold,zero mildew or zero anything..When I sell my cars the a/c is still blowing ice cold with the original compressor.

The only people I know who have issues with the a/c are the ones who keep shutting it off and turning it back on all the time..The ones that hardly use it always need a new compressor every couple of years.