Charging my AC - how is this possible? - PeachParts Mercedes-Benz Forum

1981_300sd · #1 03-03-2010, 05:27 PM

Hey all,

I posted a couple weeks ago about how my low side cap had a leak and leaked out all my refrigerant....

I got some of the enviro safe refrigerant (I know some of you dont like this, I understand and not really looking for comments about it being a bad idea

)

It states that a 6 ounce can is equal to 18 ounces of r-12. My capacity in my system is 2.6 lbs. so I ordered 4 cans so I could have some handy for recharges if needed.

I hooked up my low side, and didnt have the correct connector for high side so left that unhooked. Started the car, started charging the empty system, and it sounded like the compressor engaged, and the system was accepting refrigerant. All seemed good.

After the 2nd can, I checked the cabin to see if it was cooling, it was not. I still had a 10 psi reading on my low side so I went with another bottle. Did that one, still showing low pressure and could not tell a huge difference on cooling. I was wondering if the claims of using so much less were wrong and did the 4th can because my pressures still showed low.

After the 4th can and no cooling, I started to freak out. I took off the bottle and didnt have the valve turned off, thought it would spray all over me, but there was suction! I walked away from it for a while to research.

Upon research, I found that suction means the compressor is not fully engaging, and was thinking I really really overcharged this thing. Went out to go get a high side fitting, and for the heck of it turned on the AC, and it was very cold!

I hooked up the low and the high side, and at a little over idle, had 28 psi low side and 150 high side. So it seemed a little undercharged, and it was blowing cold.

So my two questions that are nagging me are:

1. When the bottle was off, there was a few seconds of suction, so obviously the system was sucking in air. I know air is not good to have, but is that serious enough to empty the system again and re charge?

2. How the heck could I have near ideal pressures for low and high side after 4 of the 6 ounce bottles? According to the enviro safe website, that is the equivalent of 4.5 pounds of r-12 in a system that has a capacity of 2.6 pounds.

Thanks for any help.

rrgrassi · #2 03-03-2010, 05:40 PM

Did you pull a vacuum on the system before charging it? You might still have a nice leak.

I do not understand how you can have suction on a system that shows pressure, not vacuum, when it is charged.

79Mercy · #3 03-03-2010, 05:41 PM

I also used envirosafe, no bad comments from me. I got 28 degrees out of the center vents in my W115. It took 3 cans to fill each car.

vstech · #4 03-03-2010, 06:24 PM

possibly, you misinterpreted the low pressure venting, as suction. if you are getting 28psi/150, and it's cooling and staying engaged, then I would monitor the system for a few days, and see if it maintains comfort.
keep us posted.

1981_300sd · #5 03-03-2010, 08:55 PM

Thanks for the replies. I'm pretty sure there is not a leak because the pressures are still holding steady and charged it Sunday. The reason I think there was suction is my finger got vacumed to the intake hose when I took off the last can. When I left and came back later and the ac was blowing cold, then there was pressure. I wonder if the compressor was not engaged for the entire recharge.

It took 3 cans for your cars 79mercy? What's the capacity of your systems? Either enviro safe's claim of using 33 percent less is wrong or somehow the extra gas vented out but I don't know how it would.

I mean I did put in 4 cans that equal nearly the double r12 equivalent capacity but yet the pressures arde ok so what am I not getting?

79Mercy · #6 03-03-2010, 09:07 PM

Im pretty sure my cars took 2.2 lb of R-12 originally.

If your getting cold air and your pressures are normal I wouldn't worry about it.

I find that envirosafe works best at about 30 PSI on the low side.

leathermang · #7 03-03-2010, 11:42 PM

" I got some of the enviro safe refrigerant (I know some of you dont like this, I understand and not really looking for comments about it being a bad idea

) " -- 1981__300sd

I really really do not care that you are not really looking for comments about it being a bad idea... which is it...
If this were a private email you could say that and it mean something..
but this is forum and lots of people will read about what you have done...
So by definition... it is like peer reviewed work in scientific journals... except wild west style.... if we leave dumb actions with no comment or facts attached someone else could make the same mistakes... you are free to put people on your ' ignore ' list and you will not even see their posts... that is one simple option.

I am going to keep this short...

http://reviews.ebay.com/Enviro-Safe-Refrigerant-ISN-apos-T_W0QQugidZ10000000005615832

if this is a hydrocarbon... like propane... then in many states it is illegal to install in NON STATIONARY equipment.

And aside from that ... it is just stupid to put a flammable gas into something which will be violated first in a head on accident... a situation where sparks and hot pipes are potential ignition sources.

hey_allen · #8 03-03-2010, 11:59 PM

All the commentary about hydrocarbon refrigerant is worth thinking about, but the compressor oil that is carried in the refrigerant will burn well, even in a R-12 or r-134 system, if you get a leak and a source of ignition.

That being said, I have R-134 in my car's system, and even with that, it's a good idea to learn the correct way to recharge the system.
If your finger gets sucked to the low pressure port when you disconnect the fill hose, you have something else wrong, as there should be a positive pressure in there, not to mention that it should have NO pressure applied outside the system, once the connector has been removed and the valve in the low pressure fitting closes.

To do this correctly, you need the fittings to hook up to both the high and low pressure ports, an AC manifold (the two gauge thing that you see in all the pictures of AC servicing), and a vacuum pump rated for AC work. The pump is probably the most important part of the whole mess, as you need to get the old refrigerant and any moisture out of the system before putting any new refrigerant in.

This assumes that you don't have any leaks, and that the new refrigerant is compatible with the compressor oil that is in the system currently, as well.

leathermang · #9 03-04-2010, 12:08 AM

Quote:

Originally Posted by hey_allen

All the commentary about hydrocarbon refrigerant is worth thinking about, but the compressor oil that is carried in the refrigerant will burn well, even in a R-12 or r-134 system, if you get a leak and a source of ignition.

There is always someone willing to attempt to muddy up the concept.

You need AC... those two standard refrigerants are much MUCH harder to ignite.

The point about the HYDROCARBONS IS THAT IT IS AN UNNECESSARY RISK.

::matthew · #10 03-04-2010, 12:13 AM

if having a few ounces of isobutane or propane is so dangerous to have in a fairly well protected system on your car, one would have to be absolutely insane to drive around in an RV with propane tanks onboard.

/snark

Quote:

"Non-inert Refrigerant Study for Automotive applications"

Prepared for US Dept of Energy

by Arthur D Little

John Dieckmann

Jeffrey Bentley

Page 36

"The event of most concern involve a rapid release of refrigerant into

the engine or occupant compartment. Vehicle crashes are the only likely

source of a significant number of accidental releases."

"The risk of injury from leaks into the occupant compartment is likely

to be very small with current designs because 1) the interior A/C

components are robust and well isolated from front/side crashes; 2) no

credible ignition sources were found _inside_ the occupant compartment;

3) window blowout is predicted to occur before explosive overpressures

reach the level required for injury; and 4) the thermal pulse from an

explosive event would have insufficient energy to cause life threatening

injuries. With a conventional A/C system, ... the risk of refrigerant

release and ignition in the occupant compartment appears to be very

small, approximately 3x10^7 such incidents per automobile, per year.

With approximately 140 million passenger vehicles in service,

approximately 40 incidents per year would occur if no A/C system design

changes were made. As discussed in section 6.3, we believe that this

estimate may overstate the risk considerably, as no evidence was

developed that indicates that evaporators and connecting lines within

the passenger compatrment are damaged to the point of leakage in even

the most severe collisions."

"For engine compartment leaks in an A/C system of conventional design we

estimate:

- Engine refrigerant leakage will occur in a significant number (17%)

of "towaway accidents."

- Jet mixing and dispersion will limit the probability of formation of

a flammable mixture in the vicinity of an ignition source.

- Only high energy ignition sources (broken battery cables, overheated

catalyst jacket) are likely to cause ignition

- Explosive overpressures in the engine compartment will be limited

below levels of concern (<<1 psi) due to venting out the bottom of

the engine compartment.

- Conventional systems will have an incidence of fire on the order of

14 to 50 per million vehicles resulting primarily from ignition of

refrigerant while it is leaking."

"With relatively minor redesign we estimate the annual incidence of

engine compartment fire will be reduced to less that one fire per

million cars."

I run 134a in my car, which is apparently flammable too, but luckily I haven't gotten blown up yet

bustedbenz · #11 03-04-2010, 12:18 AM

Quote:

Originally Posted by leathermang

"
And aside from that ... it is just stupid to put a flammable gas into something which will be violated first in a head on accident... a situation where sparks and hot pipes are potential ignition sources.

How much stupider can it be than having flammable liquids passing through all sorts of easily compromised tubes on their way to injectors, places that require lubrication, etc? There's fumes all over the place. Even if the gas escapes, neither the engine nor the passenger compartment are closed pressure systems. The gas would simply vent to atmospheric pressure fairly quickly, just like gasoline fumes or anything else. No huge kaboom. If anything -- and this is a HUGE if -- ignited a refrigerant leak, it would be at worst a directed propane torch through a fitting for a few seconds, or perhaps one brief flare-up of "pooled gas" that died as soon as the gas was consumed -- which in the wide open area of the engine compartment and surrounding planet would end fairly quickly, likely before injury occurred.

I don't use this stuff currently -- but they couldn't get away with selling it for this purpose if it was *that* risky. Sure, accidents can happen, but they can happen from just as many other things as well. It would be a freak accident if this happened. I'm not saying it may not be more of a risk than standard freon. I don't deny that IF it leaked out, and IF it ignited under the right conditions, it could be a risk that could have been avoided. You are absolutely correct that these are true statements. But... it's a little like comparing the risk of dying by lightning strike to dying by wildebeest stampede. Neither is really something you'd buy specific insurance against unless you're a lightning rod salesman or a herder.

Rooster300SD · #12 03-04-2010, 01:16 AM

You say you lost all your refrigerant because the cap was leaking?
If that's all that was keeping it in, you're going to lose it all again.

When the system is empty you should replace the schrader valves.
That's easy and cheap.

The R12 filling capacity for W123 and W126 is 2.8 lbs.
Don't forget the oil!
200cc to a new empty compressor
40 cc for a sudden emptying of the system
20 cc for a new condenser
40 cc for a new evaporator
10 cc for a new receiver/dryer

Jeff

BoiseBenz · #13 03-04-2010, 10:07 AM

Quote:

Originally Posted by Rooster300SD

You say you lost all your refrigerant because the cap was leaking?
If that's all that was keeping it in, you're going to lose it all again.

When the system is empty you should replace the schrader valves.
That's easy and cheap.
Jeff

An AC shop will have a little special tool which can be used to change the valves on a CHARGED system. If you change them soon enough, there may still be some charge . . .

1981_300sd · #14 03-04-2010, 10:28 AM

Geez guys, I was really trying to keep this post about the situation I am having and not another opinion war about propane being used as a refrigerant.

I completely understand your concerns and appreciate them. Lets agree to disagree on that portion, and for the sake of things lets just say I dont care if I get blown up.

With that said, I noticed that I missed some important details from my original description.

Originally, my cap and 134a adapter was leaking. Thats how the system emptied itself. Got new cap and fittings and all that, no more leaks.

I do have a manifold gauge and all that, I just didnt have the adapter for high side r12 to 134a. Thats why I only was using the low side during the charge.

As mentioned above, I thought I had the compressor going, emptied the cans in, pressures never went up, and got all 4 cans in there. Now that I think about it, I wonder if I was reading the gauge as -10 psi and not 10 PSI. In any case, it seems like I should have way overcharged the system but when I did finally get a high side adapter I was seeing 150 psi at 1500 RPM on the high side.

My two main questions remain:

1. I know some air got sucked in while charging the system, but not much. Is this a concern enough to empty the system again and start over?

2. Is it true that you should only charge 33% of the original R12 capacity with this refridgerant? If so, how was I able to get 4.5 pounds of refridgerant R12 capacity into a system that was designed for a 2.6 pound capacity?

79Mercy, I appreciate your feedback and experiences with the product. From what you are saying, it sounds like the claims of using only 33% of the original R12 capacity is not true. Your information is making the most sense so far, since it appears that in my car the sticker does say the capacity is 2.6 lbs and yours is 2.2. I did 4 (6oz) cans, you did 3. This calculation would mean that one 6 ounce can of enviro safe is equal to 10 ounces of r12. If this is the case then all is well and I can sleep easy.

Again 79Mercy, you said that you get the best cooling at about 30 psi low side - what ambient temperature are you checking this pressure at? Mine is showing 28 psi at 72 degrees ambient temperature.

Also, when I checked the vent temps, I was getting 54 degrees at the vent, but at the time I didnt know that you check with the fan speed on low. I was getting the 54 degrees at idle with the fan on high.

79Mercy · #15 03-04-2010, 04:25 PM

1. I believe that envirosafe will be OK, but not R12 or R134.

2. The only thing that I can think of is that the chart you were using is not accurate. But as i stated before if the pressure are normal and you have cold air don't worry.

I got those pressure readings when it was about 80 degrees out during the summer time.

At idle your vent temps will always be higher than when moving. Also people say that the W115 is capable of making colder air than most other models, I believe it cause its colder than my W123 and both use envirosafe.