A/C recommendations for the MB vehicles - Page 6 - PeachParts Mercedes-Benz Forum

compu_85 · #76 06-07-2011, 03:22 PM

Quote:

Originally Posted by vstech

yes. above 1000RPM usually. I like to charge a system at idle, then ramp it up to get the pressures on spec.

Do you do this for variable displacement compressors too?

wildest · #77 06-08-2011, 12:16 AM

But I only had 36 ounces of r12 (sticker calls for 46.4oz), so I used it. My pressures read 27-28 on the low side and 180-190 on the high at a fast idle, vent temps are 52 climbing to 58 sitting in 90-92 degrees ambient. Can I read this as verification that the evaporator isn't seeing a full charge, so it isn't cooling as well as it will when I top off the system? Everything else in the system is working, although the condenser has a few too many bent fins, the radiator is new.

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The aux fan comes on when the drier is hot (I don't know what that temp is, though).

leathermang · #78 06-08-2011, 08:56 AM

The condensor air flow is the bottleneck of ALL ac systems..
you need to address that cleanliness first... then re check...
Given where you live.. you might consider hard wiring the aux fan ON...The heat switch on the rec/dryer is replaceable without touching the refrigerant... it is not in contact with the pressurized gases... so easy screw out and new one in.. The other one.. the pressure switch on rec/dryer IS... so be sure to locate the temperature switch before unscrewing anything...
A system can function ok a little lower than max capacity of refrigerant...but ONE ounce over is a killer because it makes the system work way too hard ALL THE TIME...
But you may be slightly less than you need to be for refrigerant fill....bite the bullet and get it in there.. that is the only way the lubrication to your compressor functions... EEEEEKKKKKK!!!!!

compu_85 · #79 06-08-2011, 09:45 AM

So if a system is overcharged, and you run the motor at ~1000 rpm, would you see pressures that are too high?

-J

leathermang · #80 06-08-2011, 09:50 AM

I do not know if they would be ' too high'... I think what you would for sure have is not enough distance between the high and low side numbers......
so many things...like air into the condensor...which is almost never properly set up during these tests.... it is hard to quote numbers... it is the relationship between them... with the vent temps thrown in which allow safety and efficiency in the process......

compu_85 · #81 06-23-2011, 03:46 PM

Is there any way I can tell what type of oil my 134 converted car has in the AC system?

-J

leathermang · #82 06-23-2011, 04:12 PM

Have you described somewhere on the forum your AC history and current condition ? If you are inquiring about AC the chances yours is working good is pretty small.... so you are probably going to want to flush all the old oil... what ever kind it is .... out and measure the proper type and amount in as you put it back together... I do not know how to find out which oil you have and even if you know what kind... you still do not know exactly how much... so normal procedure will be to flush each item in your AC system and be sure you are good kind and amount wise...
Have you read this thread from the start ?

Hit Man X · #83 06-25-2011, 03:18 PM

Can R12 be used with ester oil?

Car has F12 and ester (I know, I know) and I do not have time to flush it now. I am not sure if I can deal with the upcoming summer with subpar city cooling.

I do have time to vent... er... evacuate the system, vacuum it down, then charge with R12. I have read in more than one place the oil is okay with R12, but wanted a definitive answer from you guys.

leathermang · #84 06-25-2011, 04:00 PM

Yes, Ester is listed as ok with R12..
not optimum , as you know.. but useable until you can address the issue..

You knew I was going to ask the obvious other question...
Why are you needing to recharge your system ?

Hit Man X · #85 06-25-2011, 06:11 PM

Quote:

Originally Posted by leathermang

Yes, Ester is listed as ok with R12..
not optimum , as you know.. but useable until you can address the issue..

You knew I was going to ask the obvious other question...
Why are you needing to recharge your system ?

Currently has Freeze 12, its low speed performance is nothing short of piss poor.

leathermang · #86 06-25-2011, 06:13 PM

WAIT A MINUTE... you asked about ester and R12....
Freeze 12 is part R134a ISN't it ?

You wrote ' car has F12 ' since R12 was mentioned several times including the original question..
I assumed that was a typo... ??????

Here is the oil charge for Freeze 12... which says it will mix with the oils used for R12...

http://www.ussap.com/Freeze-12-AC-Oil-Charge-R12-Refrigerant-Replacement_p_1132.html

but more research is needed ......

Hit Man X · #87 06-25-2011, 06:24 PM

Yes, I will be venting the Freeze 12 and installing R12.

When I installed the Freeze 12, it was on a freshly flushed system so it only contains ester at the moment.

Correct, Freeze 12 is mostly 134A (80% I think) and some other mixed refrigerant. I figured it would be like a simple 134A vent, then vacuum down, then charge with R12 since ester works with the R12.

leathermang · #88 06-25-2011, 06:26 PM

But how will you know how much to put in ?
and why are you not going with Castrol premium cold flow 500 for the R12?
So you have not had a leak... you just need more cooling there in DFW area ?
Ester is compatible... but not optimum... but will probably get you to fall... that starts Jan 4, 2012.

Hit Man X · #89 06-25-2011, 06:44 PM

Quote:

Originally Posted by leathermang

But how will you know how much to put in ?
and why are you not going with Castrol premium cold flow 500 for the R12?
So you have not had a leak... you just need more cooling there in DFW area ?
Ester is compatible... but not optimum... but will probably get you to fall... that starts Jan 4, 2012.

It currently contains ester as that was the oil charge from the Freeze 12 cans. No idea how much to add upon a vent, will ester mix with mineral? If so, I have some I can add. If not, I will just buy a small bottle of ester at the local auto store.

Correct, no leak. Just lackluster performance at best.

leathermang · #90 06-25-2011, 07:05 PM

I suggest until the flush and changeover you stick with the ester since you are sure that is what it has now...