I am not familiar with how exactly to charge a system, but the pumps I referred to earlier utilizing an air compressor claim they are capable of creating a vacuum down to 29.82" I think. As long as you are creating lower than current outside pressure, would you still be succesful in removing any moisture?

Using the A/C gauges, my two stage compressor with a 3 hp motor will go down to about an indicated 22 in. vacuum, we are at about 1800 ft above sea level.

Tim: Can you describe how you used your compressor and a/c gauges to pull a vacuum? I have a 2 hp Campbell Hausfeld compressor for air tools and the like, and was wondering if I could use it to vacuum my system before recharging. Did you have to make up adapters to attach the compressor intake to the a/c system? I'm really intrigued by this.

Thanks for your help.

Sure. My compressor is old but pretty big. It uses a standard 3/4 inch pipe thread for the input. I just unscrewed the air filter, fit a reducer from 3/4th to 1/4th, and attached my air hose. The fittings on the A/C gauges seem to connect to a standard 3/8ths (I think, but can't remember) flare fitting which I attach to the air line.

One last thing. Since I use HCs, I disconnected the output line to the tank from the compressor so the air evacuated from the A/C lines did not go into my 100 gal. tank.

Hope that helps.

Scott, I am glad you asked that question because it was the next one coming from me!
Another question for Tim, though... With gauges on one side of the AC compressor and your compressor plumbed to the other side, I take it you just shut off your compressor when reaching max vacuum? Also, does the compressor not have any problem with the restricted airflow on the intake side? Seems like it would react adversely somehow... But then again, I've never done any AC work before and am just trying to learn how to make do with tools on hand! So, thanks for the help!
Brian

Brian: My little oilless compressor might start heating up a bit, but I'm guessing it will handle the vacuum just fine.

Scott

I just talked to the owner (I think) of DuraCoolusa.com He said, you only need to pull a vacuum if you replaced a component. And you only need 10" of vacuum when you do that.

He went on to say, you only need a static (0 pressure) in the system to install DuraCool. Moisture is not a big concern with DuraCool, as it does not contain Chlorine. I guess when you mix Chlorine with moisture you get a corrosive.

So I ordered a case. It should be here next week. Even though, I only need 2 1/2 cans. Knowing my luck, I won't get it on the first try.

Environ-Safe's claims look attractive. However, I have some issues (as have others) with their suggestions:

"2 - If desired, pull a vacuum of no more than 10 inches. Unlike freon, Enviro-Safe does not become caustic if moisture is present. Charging under a high vacuum can result in an overcharge. Any overcharge may cause loss of cooling efficiency. "

As Jim pointed out, moisture in the system can cause the expansion valve to freeze and prevent refrigerant from entering the evaporator. The system, under vacuum, will only draw in only as much as you allow from a can. They aren't selling 50 lb. tanks are they?

"3 - Connect gauges and hoses. With compressor off, open cylinder valve or invert can to install Enviro-Safe on low pressure side of compressor (installing as a liquid will not harm the compressor)."

The A/C compressor compresses vapor; it's not a pump (liquid). Typically, only vapor refrigerant installs in the low side. If liquid refrigerant goes into the compressor, it will kill the compressor. It's like filling up an engine cylinder with a liquid (don't try this at home). Maybe they're thinking the system will somehow equalize with the system under vacuum with the compressor OFF (don't think so).

"5 - If a system has been overcharged or has a leak and must be recharged, completely evacuate the system using reclaiming equipment and start the charging procedure over. "

As I mentioned before, no A/C shop is going to "contaminate" their recycling/reclaiming equipment and refrig. tanks with a foreign substance. If it isn't R12 or HFC-134a per their refrigerant identifier, they won't connect to your vehicle. The makers of Enviro-Safe probably realize this and are CTA.

Rejected by their A/C shop, users instead will simply vent the refrigerant to atmosphere. Follow your own conscience (like pouring oil in the gutter). While they claim it isn't a hydroflourocarbon and the release volume probably isn't a whole lot, it is a hydrocarbon.

Sherwood

"3 - Connect gauges and hoses. With compressor off, open cylinder valve or invert can to install Enviro-Safe on low pressure side of compressor (installing as a liquid will not harm the compressor)."

This is likely how they are getting an overcharge of the system (not too high of vacuum); I bet people are just buying a can tap and cans and adding the mix until they feel they have enough in the system! Without a running system and gages there is no good way to tell if one has a proper charge or not. Sounds like an unfortunate way to get a hose rupture or compressor head failure combined with a flamable gas.
:eek: Jim

Tim: Do you connect the compressor/vaccum to one of the hoses on the a/c manifold set up, and then connect the manifold to one of the schrader valves on the compressor? High side? Low side?

The reason I ask is that I'm wondering how you disconnect the compressor/vacuum without allowing air back into the system.

Thanks for the info.

Those are not the directions I am following.

Every direction I have read, whether R134a or R12 and Duracool R12a, tell you to install the can upside down on the low side so it will enter as a liquid.

I don't know why...:confused:

But under 60 PSI (and in the can) this is a gas... correct??? And at higher pressures ~100 - 150 (high side) it is a liquid.. RIGHT?

Then as the liquid goes to gas (via the expansion valve) it goes cold.

SOOO entering this in the low side, from the can it should be a gas. I presume you are turning the can upside down so you get the refrigerant and not the "inert" gas....
:confused:

Anyways... I will see next week.

I recall the first can is charged with the compressor off, so liquid is OK, but then they still tell you to charge the second can with A/C on and the can inverted (charging liquid). I was nervous about doing this, but I have succesfully done this twice.

Wonder if it has anything to do with the fact this stuff is a blend? Different partial pressures of the the gas? Maybe I am too dumb to be thinking about this??? :)

Nick, you've got it backwards, I think: the gas is at higher pressures. When the gas hits the expansion valve, the pressure drops and it turns into a liquid and that change in state removes heat from your car and makes your air nice and cold. :)

The guys at Enviro-Safe and Duracool tell us to do things bass ackwards from things I have been taught on residential A/C systems. I'm just an amateur, though.

jurgen

I assume you guys have read Chris Bennett's link to:


US EPA Legal status of HC-12a®, DURACOOL 12a®, and OZ-12®

My contact at Toyota calls these hydrocarbon refrigerants, "rocket fuel". For those of you who think this is no less hazardous then pressurized fuel from the tank to the engine, consider that fuel lines don't run through the car interior like A/C lines tend to do. In addition, fuel is usually in a liquid state, not in a more combustible vapor form like refrigerant inside the evaporator (which sits inside the car). One might consider hydrocarbon-based refrigerants more hazardous to use because of this.

BTW, refrigerant is in a high-pressure liquid form from the compressor to the expansion valve where it vaporizes and absorbs heat in the evaporator. It is in a vapor form all the way back to the low-pressure side of the compressor.

Back to a basic question. What's wrong with using HC134a? It works (though not quite as efficient as R-12); it's readily available, it's safer, the system is serviceable most everywhere you go and it's ... legal.

If your A/C system isn't working due to some design deficiency from the factory, I'd consider updating it (e.g. more efficient compressor, etc.). In addition, one can increase airflow to the condenser, clean fins, evacuate and recharge system w/proper amount of refrig., etc.

You don't want moisture in an A/C system and you cannot drive off moisture using only 10" of vacuum. You need more like 25".

Sherwood

Well, I don't know about where you are...

But here in CA - for a shop to do the conversion to R134a (by LAW) they have to replace all the non-barrier hoses. :rolleyes:

BEFORE they replace the hoses, they have to recover the refrigerant $49.99 is the best price I found.

Last I checked, they wanted $500 just to replace hoses... :(

Now they have to replace the drier/accumulator (I have found it as low as $19.99) because it's not R134a compatible.

Vacuum and leak check again $79.99.

NOW the cost of installing the less than efficient R134a... $40 - 50.

Now they can see if the system is running appropriately. If not, they get to vacuum it, fix/replace the evaporator valve (found this for $24.99). ANNDDD again $79.99

So I can do it myself for $80.00 (with R12a) assuming nothing is wrong

Or I can have it done legally for $600+ - assuming nothing is wrong.
:eek:

why not run something like Freeze12 which I believe is not flammable and is approved for auto use? I believe that's what's going into my system tomorrow when the new compressor/reciever/dryer/expansion valve are installed.

I assume you read it too... Specifically #10

[/b]
Is it legal to replace HFC-134a in a motor vehicle with hydrocarbon refrigerants such as DURACOOL 12a® and HC-12a®? [b]
In certain circumstances, the replacement of HFC-134a in a motor vehicle with hydrocarbon refrigerants might be permitted. At a minimum, in order to avoid violating the Clean Air Act, the motor vehicle A/C system must have either been originally designed for use with HFC-134a refrigerant, or must have been previously retrofitted from CFC-12 to HFC-134a refrigerant, AND no sham retrofit must have occurred to convert the system to the hydrocarbon refrigerant. In order to avoid violating other laws, the replacement of the refrigerant must not violate any state or local prohibition on the use of flammable refrigerants in motor vehicle A/C systems.
The following 18 states ban the use of flammable refrigerants such as HC-12a® and DURACOOL 12a® in motor vehicle air conditioning, regardless of the original refrigerant: Arkansas, Arizona, Connecticut, Florida, Idaho, Indiana, Iowa, Kansas, Louisiana, Maryland, North Dakota, Oklahoma, Texas, Utah, Virginia, Wisconsin, Washington, and the District of Columbia.

SmileWavy

I do still agree it can be a deadly mixture. The biggest problem I see is not how flammable it is, but how suffocating it is in an enclosed area...

As I recall, this is heavier than air, and it disperses oxygen. Hence, in a small cabin, such as our car, it can disperse the oxygen if htere is a leak in the evaporator... :eek:

I couldn't find it... :(

Where did you find it?

Todd: Are you still getting your a/c charged on Friday? It'll be a nice HOT day. Let's us know the results.

Scott

I feel the hydrocarbon refrigerants are superior to the freon stuff (well maybe not R-12), BUT use of hydrocarbon refrigerants is not a license to take short-cuts. You still need to have the equipment and be prepared to take the time to do the job right. I think part of the problem is guys think this stuff is a quick fix.

Let's do some math. Propane, in gaseous state fills 8.5 cubic feet per pound. For most A/C systems, it takes 12-20 ounces of hydrocarbon refrigerant. So, for lightweight systems, the fill is .75 lbs, and for bigger systems, 1.25 lbs. Let's say you had an accident and the evaporator was damaged and permitted to fill the passenger compartment. The .75 lbs would fill 6.5 cubic feet, and 1.25 lbs would fill 10.625 cubic feet. The Lower Explosive Limit is 1.4% for isobutane and 2.1% for propane, so ignition would require a passenger space of 464 cubic feet for .75 lbs and 758 cubic feet for 1.25 lbs. If my math is right, then it is virtually impossible for a release of propane/isobutane to ignite inside a SEALED passenger compartment.

The drawbacks to hydrocarbon refrigerants: 1) not EPA approved, 2) not in wide use by industry inside USA. I think the reason for the 2 drawbacks is plain and simple, MONEY.

Interestingly, Duracool and Enviro-safe are more expensive than R-134a. Those boobs are shafting the consumer.

just my opinion,
jurgen

You need to pull a vacuum but you need to maintain that vacuum anywhere from 45 minutes to 2 hours in order to remove all the moisture in the system. Pulling a vacuum for 5 minutes will not remove all the moisture. The longer the system was opened to the air, the longer you must pulled the vacuum.

There has been a previous thread on these conmpressor vacuum machines and everyone who had use it in the past has said they will never do it again

Save your money and go out and rent a vacuum machine.