Industrial ES12A= 40 degrees F - Page 2 - PeachParts Mercedes-Benz Forum

Oracle12345 · #16 08-20-2008, 07:12 PM

400 and 150 is how much vacuum it should be pulling.

25-35 psi is normal for low

150-200 psi is normal for high

airedale2 · #17 08-20-2008, 07:38 PM

Correction, 29inhg for vacuum. Sorry, i was thinking blood pressures.

Matt L · #18 08-20-2008, 07:39 PM

Quote:

Originally Posted by Oracle12345

400 and 150 is how much vacuum it should be pulling.

25-35 psi is normal for low

150-200 psi is normal for high

Now you're really confusing me. Do you mean 400/150 microns (micrometers of mercury above absolute vacuum)? If you have 150 microns on the low side, you should also have 150 microns on the high side, right?

airedale2 · #19 08-20-2008, 07:41 PM

25-35 might be more on the high side for this refrigerant as well. I am shooting for 25 as a high. The low side pressures could go as low as 18 from what i understand with this gas.

airedale2 · #20 08-20-2008, 07:46 PM

The gauge reads in "inhg". I assume the manufacturer to be correct. Either way, I have 40 degrees at the vent. Two identical systems could require different amounts of refrigerant and pressures with identical components. Ive learned through life, that life doesnt follow a set path. My current job neither. You have to make adjustments and corrections. But be careful, one day some one will correct you.

zeke · #21 08-20-2008, 07:47 PM

How much was you mpg suffering?

I am wondering if r134a is dragging my 240D mpg down.

I plan to retro-retrofit to R12 next spring. Just wondering what your mpg was before and what you hope it will improve to.

Matt L · #22 08-20-2008, 07:48 PM

It's the evaporator temperature that is important. 25 may be too low. You want to limit the compressor cycling as much as possible. I don't know that 25 is too low for that, but it is too low for 134a. You could put an indicator lamp connected to the compressor clutch to detect cycling while you're driving.

Now, you cannot get a constant low-side pressure with that R4 since it is not variable stroke, so you'll have to shoot for something that is optimal at high temperatures. I know that you see some of those.

Matt L · #23 08-20-2008, 07:50 PM

Your vacuum gauges reads in inches of mercury below atmospheric pressure. The micron rating used for a "real" vacuum gauge reads in micrometers above an absolute vacuum. It's a more accurate measure both because it is in a finer increment (it's not one micron, but is a lot finer than what you can see on your gauge) and because you don't have to take the current air pressure into account.

airedale2 · #24 08-20-2008, 07:54 PM

Zeke/Matt,

Mpg with no compressor, 26-28mpg minus my lead foot. 22-24 with ac on with r134.
Looking at about 26 with es12a, and the compressor does not seem to cycle very often. Sorry gotta go, the wife demands her cuddling time now. Be back later.

Oracle12345 · #25 08-20-2008, 07:54 PM

Quote:

Originally Posted by Matt L

Now you're really confusing me. Do you mean 400/150 microns (micrometers of mercury above absolute vacuum)? If you have 150 microns on the low side, you should also have 150 microns on the high side, right?

For the low pressure line you should be reading 150inhg and the high side, a good one should be reading 400 inhg and yes that is correct. The right temperature in the cars cabin should be 35-45 degrees farenheight. If not you have a problem somewhere.

150 and 400 are guidelines used for when the car is not running. When the car is running it should be at 150

Oracle12345 · #26 08-20-2008, 07:56 PM

Quote:

Originally Posted by Matt L

Your vacuum gauges reads in inches of mercury below atmospheric pressure. The micron rating used for a "real" vacuum gauge reads in micrometers above an absolute vacuum. It's a more accurate measure both because it is in a finer increment (it's not one micron, but is a lot finer than what you can see on your gauge) and because you don't have to take the current air pressure into account.

Mercury is used a measuring stick because it is more practical and accurate. In theory you could use water but you would need a Very tall container, ie the height of some warehouses.

Matt L · #27 08-20-2008, 08:51 PM

Quote:

Originally Posted by Oracle12345

For the low pressure line you should be reading 150inhg and the high side, a good one should be reading 400 inhg and yes that is correct. The right temperature in the cars cabin should be 35-45 degrees farenheight. If not you have a problem somewhere.

150 and 400 are guidelines used for when the car is not running. When the car is running it should be at 150

Now I understand what you are saying. Thanks for the clarification. I don't think I've seen inHg used for AC pressures before.

airedale2 · #28 08-20-2008, 08:53 PM

Oh great Oracle, thank you for your enlightenment. Forgive this simple fireman for not using "technical terminology." I wondered how long it would take before someone with too much time on their hands would start to micromanage the thread. I guess I try to keep things simple, the hose goes off, i follow it.

Anyone with any further questions regarding my ac system, please feel free to ask a question. I will try not to belittle you. No question is to stupid, just me apparently, and i will try to answer to answer it to the best of my knowledge without being condescending. By the way, the propane was $5.60 a can.

Matt L · #29 08-20-2008, 09:36 PM

Is that $5.60 for a six-ounce can? Pretty expensive for propane (etc.), but you and I both know that the cheap propane that goes in your backyard grill is not very clean stuff.

A few years ago that would have looked especially promising, but 134a has come down in price. Not that you would be happy with 134a without a whole lot of additional work, I'm sure. I am genuinely interested in the performance of the system, especially since you charged it into a hard vacuum. Not that I think that air belongs in there, but one of the HC refrigerant mfrs recommends it.

And for the hijack, while "in theory" you could use inches (feet?) of water as a unit, you could not literally use water for the vacuum gauge while you could literally use mercury. If you pull a near-perfect vacuum on a column of water, it will begin to boil unless it is already very cold.

JamesDean · #30 08-11-2011, 09:47 PM

Any updates to this thread?

I know its been a while but I was reading this after I charged up my dad's SD..

It previously had some Freeze12 in it that wasn't quite cutting it.

I recharged the system up today and these were my readings:

70F Ambient. 1200-1500 RPM. No aux fan or fan at condenser running.
I put in approx. 8-10 Oz of ES-12a through the low side.
Low Pressure: 14-16 psi
High Pressure: 145-150 psi

I based these values on the standard R12 charts (http://www.ackits.com/aacf/ptchart.cfm) which said for 70F you want 14 low, and 150-180 High.

It said that ENVIRO-SAFE ES-12a pressure on the high side may run up to 15 psi lower than what your R-12 high side pressure normally is... So I believe my high side to be within the range..

A quick drive around and I was getting low 50's high 40's at the vent. Can anyone give me an analysis? I was hoping for high 30's low 40's...