How important is A/C Evacuation?

[davew833]

OK, so my AC leaks, probably from the compressor hose fitting O-rings. So, assuming the system now has zero or very little pressure and I pop those fittings off and put new o-rings on in 10 minutes or less, do I really need to evacuate the system before recharging? I'm sure it's a good idea, but is it really necessary?

[Schralper]

Originally Posted by davew833

OK, so my AC leaks, probably from the compressor hose fitting O-rings. So, assuming the system now has zero or very little pressure and I pop those fittings off and put new o-rings on in 10 minutes or less, do I really need to evacuate the system before recharging? I'm sure it's a good idea, but is it really necessary?

yes you need to vacuum the system. I'm doing this RIGHT now.
the once vacuum is achieved and held you can add r134.
what about a/c oil? do you have any leaks showing?
might need fresh compressor oil.
make sure you use the green orings.

[ZMan]

Google is your friend.

http://www.jarcrib.com/2010/05/10/ho...car-ac-system/

http://en.allexperts.com/q/Auto-Air-...ng-AC-Unit.htm

http://www.freeautomechanic.com/airconditioning.html

http://www.aa1car.com/library/ac98.htm

http://highperformancehvac.com/comme...ion-evacuation

[davew833]

The whole process would be easier if someone hadn't lifted all my A/C equipment out of my garage. I hope they needed it more than I did.

[ensteele]

I put all of the links into the How-Tos.

[SVX_MY_BABY]

Great links.

Anyone know the correct fully charged low side pressure for our system?

You can buy cans of "drier" on the market to add along with your refrigerant, but I have no idea if they are a good idea.

[Green1995SVX]

Please allow me to post my own experiences. A 92 SVX I owned had no AC for about 2 years. One hot summer day I decided I was going to get an interdynamics kit and charge it up. I charged it and clearly it was leaking from one of those compressor o-rings. I replaced the o-ring, charged it again, and the car had cold AC for the remaining 3 years that I owned it. I never evacuated anything.

[ensteele]

I have recharged a few and had the same luck. They all work and until I got a unit for pressures and a vaccume, I never evacuated any of them.

I have also found out (I am doing a How-To on it) about Hot Shot, which replaces R-12. It is a much better product if converting. It is also compatable with the same oil and does not require barrier hoses or new O-Rings. It is a direct replacement of R-12.

Here is the website for the product.

[davew833]

I used to have a terrible time when I was buying/driving '80s Hondas. It seemed like every one I bought had a seized A/C Compressor and no matter how careful I was in replacing it, including replacing the filter/drier, professional evac & recharge, etc., none of them worked for very long. I got to wondering if Honda A/C systems and components just weren't well designed.

I wonder how Subaru compares? All of my SVX's have come with working A/C, which is a point in their favor. I had one old Loyale wagon that came with R-12 A/C that was bone-dry empty. I got one of those cheap Interdynamics "death kits" to convert it to R134a withougt changing or evacuating, and it worked OK for over a year. Are Subaru systems just more robust?

[kwren]

The SVX air conditioning system has built in safety components that would prevent sucking air that would contain damaging moisture and it would be rare that evacuation would be necessary. A compressor that goes bad could be the exception, depending on the circumstances.

Keith

[ZMan]

Originally Posted by kwren

The SVX air conditioning system has built in safety components that would prevent sucking air that would contain damaging moisture and it would be rare that evacuation would be necessary. A compressor that goes bad could be the exception, depending on the circumstances.

Keith

Read the first post.

We're talking about a closed system that has been opened up to the atmosphere.

Any freon that was in the system is GONE and replaced with AIR.

Air has moisture and depending on the humidity level at the time, a little or a lot.

I know everybody jumps on a post like this to say they didn't evacuate the system and it worked ok, so it's not necessary.

Well, i know a few people who smoked all their lives and never got cancer, so i guess smoking is not harmful to your health after all!

[zavikan]

I agree with the above post. Unfortunately, the degree of 'hack' one deems acceptable is subjective....especially when people don't understand what they are hacking. Don't cut corners unless you know why your doing it (beyond $$$).


I am curious what this safety system is supposed to do to prevent it 'sucking in air'....it certainly doesn't prevent the coolant from leaking out, or the air from taking its place....perhaps your talking about the low pressure compressor kill that all modern cars have that prevent the compressor from spinning if the system has obviously become compromised? This doesnt prevent the system from becoming compromised in the first place though.

[kwren]

When the pressure in the system reaches a low level, not near as low as atmospheric pressure, the compressor will not turn on. hence... air is never sucked in.

Keith

[Hocrest]

But if the system is "opened" by disconnecting any of the fittings or a severe leak, air and moisture does get into the system.

I've recharged without evacuating. Sometimes it works, sometimes it doesn't. If your willing to waste a charge go for it and see if it works... If it doesn't work, waste the charge and evacuate.

[ZMan]

Originally Posted by Hocrest

But if the system is "opened" by disconnecting any of the fittings or a severe leak, air and moisture does get into the system.

I've recharged without evacuating. Sometimes it works, sometimes it doesn't. If your willing to waste a charge go for it and see if it works... If it doesn't work, waste the charge and evacuate.

Not only a waste of a charge but this also:

"If you do not evacuate your system prior to charge, it may work for awhile, but the moisture will eventually cause corrosion and other unwanted chemical reactions in your A/C system. This will shorten the operating life of your A/C system."

Quoted from my first link.