R12 System - Evacuate or not? - PeachParts Mercedes-Benz Forum

ttownthomas · #1 02-20-2018, 02:59 PM

On my W126 300SEL The air is not cold.

The compressor kicks on but I am not getting much cooling if any, I know theses systems are somewhat complex but it seems to me like the appropriate vents are opening and closing based upon the different modes.

I have 2 cans of R12 but have read that "topping it off" is not advisable because you are not filling to the proper level and I don't have enough coolant to replace all of it. I also cannot seem to find a shop that will mess with R12 to even evacuate it properly.

I live in NC and want to daily drive this car but the summer here is no joke.

I spoke to a shop that suggested I just top off the R12 by adding it to the low side and watch the sight glass carefully to ensure the bubbles dissipate and call it good.

I am floating in the dark here as my expertise here is very limited.

Chris

fonzi · #2 02-20-2018, 03:16 PM

If you evacuate, are you going to capture what’s in there? Or vent it to the environment? I don’t think it’s easy to find a place that will capture it anymore. I could be wrong.

The reasons for evaporating are to assure you have the right mass and also assure the system is dry. My opinion is that if the system is still pressurized on the low side, then you are unlikely to have taken on significant moisture. I think evaporating this time of year is a horrible idea, since the hotter it is, the easier it is to evaporate any water in the system. Only evaporate if you have no pressure. That’s my VERY unprofessional opinion. Charge it by the low and high side pressures, and do everything you can to minimize r12 in our environment.

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ttownthomas · #3 02-20-2018, 05:56 PM

Quote:

Originally Posted by fonzi

If you evacuate, are you going to capture what’s in there? Or vent it to the environment? I don’t think it’s easy to find a place that will capture it anymore. I could be wrong.

I would rather capture it but I have not researched how.

Hit Man X · #4 02-20-2018, 04:40 PM

Are all of your vacuum pods actuating correctly? Check the recycle door. Verify the monovalve is closing too when on Max AC. Fan clutch actually work? Few do with age... a hint? Sachs ones are the only that work in my experience, spend the extra money for them. Also use the later fan for the M103.

Clean the condenser, the dual fan ones are a prick to do. Just do it. The evap needs a cleaning at this point too. 'Evap Powr-C' works boss for this procedure, just pick up a hand actuated container and wand to apply. It will take work, but worth the trouble.

If you have a leaky system, save the R12 for now. You probably have original orings and a leaking compressor. BTDT. Reseal the entire thing while it is cool out and flush it. Seriously. Use a syn compressor oil. Mastercool for the vac pump and Yellow Jacket or MC for the gauges.

A quick, cheap charge is with 152A if you just need to get by...did this in the 300E for years before it met its demise. Multiply your charge weight, 2.9lbs on the W126 by 0.54 and that is your 152A charge. Yes, it is air duster. It works as well as R12 pressure wise and cooling wise. You need two full, 10oz cans and one half of another. The last you have to meter in via pressure. I use R12 charts. Now if you can find 12oz cans, you are perfect. Two of them is pretty much full. Three, 10oz cans at my local Walmart are $12.

BTW, the car will never cool with faulty recycle and defrost pods. Tint will help cool the W126 vastly also. Even a mild 50% quality film.

ttownthomas · #5 02-20-2018, 06:05 PM

Quote:

Originally Posted by Hit Man X

Are all of your vacuum pods actuating correctly? Check the recycle door. Verify the monovalve is closing too when on Max AC. Fan clutch actually work?

Clean the condenser, the dual fan ones are a prick to do.

If you have a leaky system, save the R12 for now. You probably have original orings and a leaking compressor. BTDT.

A quick, cheap charge is with 152A if you just need to get by

Tint will help cool the W126 vastly also. Even a mild 50% quality film.

So I assume there is a procedure to check the monovalve and the vaccum pods in the FSM?

Will do on the condenser.

Plan to tint to 35%

Diseasel300 · #6 02-20-2018, 05:43 PM

Before getting all carried away, grab hold of the return line up by the brake booster and see if it's cold and/or sweaty. If it is, you know you have a problem with the air doors, OR you have an issue with the monovalve not shutting off all the way. If it leaks through, the amount of heat the heater core throws is enough to cancel out any cooling that takes place from the A/C system.

Are you also CERTAIN that the compressor is coming on? You see the center section of the pulley pull in and start spinning? If you're low on refrigerant, it's likely that the compressor will cycle a lot.

ttownthomas · #7 02-20-2018, 06:08 PM

Quote:

Originally Posted by Diseasel300

Are you also CERTAIN that the compressor is coming on? You see the center section of the pulley pull in and start spinning? If you're low on refrigerant, it's likely that the compressor will cycle a lot.

The center section is definitely spinning. Don't know if its pulled in or not. Ill have to look again tonight.

Thanks for all the pointers everyone.

Diseasel300 · #8 02-20-2018, 06:20 PM

Quote:

Originally Posted by ttownthomas

The center section is definitely spinning. Don't know if its pulled in or not. Ill have to look again tonight.

Thanks for all the pointers everyone.

The pulley ALWAYS spin on the compressor. Just because it's spinning doesn't mean the compressor is engaged. Look at the center hub of the pulley. With the compressor off it will be stationary. If the compressor is engaging, you'll see it suck in and start spinning with the rest of the pulley.

Hit Man X · #9 02-20-2018, 07:27 PM

Quote:

Originally Posted by Diseasel300

Before getting all carried away, grab hold of the return line up by the brake booster and see if it's cold and/or sweaty. If it is, you know you have a problem with the air doors, OR you have an issue with the monovalve not shutting off all the way. If it leaks through, the amount of heat the heater core throws is enough to cancel out any cooling that takes place from the A/C system.

Are you also CERTAIN that the compressor is coming on? You see the center section of the pulley pull in and start spinning? If you're low on refrigerant, it's likely that the compressor will cycle a lot.

Great points.

I just assume the worst with 30 year old HVAC systems.

Diseasel300 · #10 02-20-2018, 09:11 PM

Quote:

Originally Posted by Hit Man X

Great points.

I just assume the worst with 30 year old HVAC systems.

For sure! But if the system still has a charge of R12, I sure wouldn't be emptying it unless I had to!

ttownthomas · #11 02-20-2018, 10:27 PM

https://youtu.be/f5VsbD5RVu8

The compressor is spinning. ^ I have not noticed it cycle off at all unless the a/c is turned off.

The high pressure line is not cool or sweaty

TOPGUN · #12 02-20-2018, 11:10 PM

The low pressure side is cool not the high side. The low side line is the larger. The high side should be hot.

lsmalley · #13 02-21-2018, 02:04 AM

This is my opinion from personal experience and logic. Ditch the R-12. You will probably not find anyone that is licensed or willing to evacuate it. Sorta like trying to purchase a new 8 track tape or VCR. R-12 is done. Sooner or later the compressor will go, if it already hasn't, then what? You need not switch to R-134a either as it is junk in our old systems. What I have done after struggling with extreme heat in southern California desert is get rid of the converted R-134a in my system and run R-152a (Air Duster). I have posted on the site of the great success with the temps cooling way more than the 134. R-152 is plentiful, cheap (just got two 10 oz cans for less than $8.00), and you can release it freely into the atmosphere without fear of ozone depletion. Also, you can continue to use whatever oil is in your system to carry it. I am using PAG oil. I actually just bought 2 cans a few days ago because I noticed a small leak of oil at the suction line connector, I think I crushed an o-ring. But this o-ring swap will not be a $200 o-ring swap like it would be if I was running r-134. Use logic and think of the pros and cons of running the R-12 vs R-152. Good luck. PM me if you have questions for me personally about my conversion.

ttownthomas · #14 02-21-2018, 09:09 AM

Quote:

Originally Posted by lsmalley

This is my opinion from personal experience and logic. Ditch the R-12. You will probably not find anyone that is licensed or willing to evacuate it. Sorta like trying to purchase a new 8 track tape or VCR. R-12 is done. Sooner or later the compressor will go, if it already hasn't, then what? You need not switch to R-134a either as it is junk in our old systems. What I have done after struggling with extreme heat in southern California desert is get rid of the converted R-134a in my system and run R-152a (Air Duster). I have posted on the site of the great success with the temps cooling way more than the 134. R-152 is plentiful, cheap (just got two 10 oz cans for less than $8.00), and you can release it freely into the atmosphere without fear of ozone depletion. Also, you can continue to use whatever oil is in your system to carry it. I am using PAG oil. I actually just bought 2 cans a few days ago because I noticed a small leak of oil at the suction line connector, I think I crushed an o-ring. But this o-ring swap will not be a $200 o-ring swap like it would be if I was running r-134. Use logic and think of the pros and cons of running the R-12 vs R-152. Good luck. PM me if you have questions for me personally about my conversion.

I have no aversion to switching to a non-tradidional refrigerant. Once I figure out if my system is functioning correctly I will definitely reach out.

Diseasel300 · #15 02-21-2018, 09:35 AM

Quote:

Originally Posted by ttownthomas

I have no aversion to switching to a non-tradidional refrigerant. Once I figure out if my system is functioning correctly I will definitely reach out.

The way to do that at this point is to get a set of gauges and find out what your pressures are. Since you know the compressor is actually running there's gas in the system. OR there's an electrical fault. The original problem with my SDL was a stuck KLIMA relay that let the compressor run with no refrigerant. It turned the compressor into a hunk of melted and galled aluminum.

If you convert to a new refrigerant, you've got some work in front of you. At the very minimum, a flush of the system to purge the mineral oil out and a new filter dryer. If you want to do it right, all new O-ring seals and a new expansion valve rated for R134a should be added to your list.

I've joined the list of people who don't understand the aversion to R134a. If the system is converted properly, it works fine, at least in the Gen II 126 with the small-tube condenser. My SDL cools better than my Honda does. Even on a 110˚ day, it has no problem keeping up and I have no window tint. I've run R152a and R290 (propane) and found them both to be lacking at lower speeds in the city.