Thanks for the tips guys.....

My temps tend to go up about 5-8 degrees when at idle...with the fan on high. The pressure seems to be OK. I have checked it with a gauge that came with the car (along with an extra can of "Johnsen's Freeze 12") and it indicates pressures in middle of the "Green Zone." The air can be finger numbing cold coming out of the vents (41 degs)....as long as the fan is on low.....but that isn't enough to cool the car on a moderately hot day. On high (and automatic), the vent temp rises and it doesn't get the interior cool enough to be comfortable....even on long trips. It is sufficient at night. My car is white, by the way....I know there have been some discussions about the relationship between the color of the car and heat buildup.

Oh, I'm just curious...what are the symptoms of an overcharge in the a/c system?

Thanks in advance,
Keith

Overcharging will have high pressure readings. Is the expansion valve new?

It sounds like you don't have manifold gauges. Trying to correctly charge any system, but ESPECIALLY a converted system without monitoring high and low side pressures is flying blind.

Can you borrow some gauges somewhere so that you can monitor both sides and post your pressures along with the ambient and vent temps.

Good luck,

Props to Diesel Giant for a great site!
 

:)

Keep up the good work!

Get a good set of guages. They are around $75 and can tell you tons of info about your system.

Lost in the conversation
 

I hope this post doesn't get lost in the middle of this great conversation, but it seems like one of the best places to post.
My '82 240D has the R134 AC system and I have added freon recently.

The problem is, when I drive in town, about 20 to 30 minutes into the drive - this is with stop lights and traffic, but not stop and go rush hour traffic - the AC stops blowing cold air. It starts to lose its punch and then dies. I still get air from the fan, just nothing cold. It will actually blow hot air on a hot day. Adding freon does not fix it. If I park for 30 minutes with the engine off, it will blow cold again.

Any ideas what could cause this? I don't want to jump into re-building the whole system if it is a far simpler issue.

I believe (and will have to look it up in my records) that the AC system was worked on by a mechanic about 5 years ago. This could have been my other car though, I cannot remember off the top of my head.

Thanks for any help.

Search
 

Aux cooling fan and fan clutch.
Should be your issue.

You need a good set of A/C guages. Drive the car and keep the guages with you. When the A/C starts acting up hook up the guages and tell us what the high and low side read.

That was almost as good as the "Left behind " series.
Thanks :D

What was?

I made the page a seperate entity so it will load faster.

Tell me if you all think is works better on your system.

I should now load much faster!

opps now it will load faster.:eek:

134a aroma?
 

Hi all, great thread.

Just curious about R-134a.....does it have an aroma?

I have noticed what might smell close to a strawberry or similar aroma that I think may be associated with my AC....I resently bought my w124....and the AC wasn't cold. So I recharged it....Everything was good for a couple of weeks. Then basically it gave up due to low freon. So i recharged again Saturday...two days ago. It's working again. I'm thinking I have a leak. Maybe near the evaporator.... because I noticed the aroma this AM. However the system was OFF and so I left it off. I know a real leak probably doesn't care if the system is on or off. It wasn't hot enough to need the AC and my driving time to work is pretty short. Any aroma may have been partially due to the fact the car was closed up all night and held the various gases. Then I start the car in the morning and perhaps got a whiff of the collection which accumalated over-night

More information as I go through this period of evaluation should be expected in the near term if the system is actually leaking.


Thought I'd leave a question to this excellent forum in the effort to get a early response.

Thanks in advance,

Ron_of_orange

1992 300ce w/83k

No 134a does not smell like any type of fruit. Get the system leak checked bacause 134a does cause testicle cancer, so you dont want to breathe it.:eek:

Same goes for blends like Freeze-12, which is 80% R134a.

All refrigerants are "blends" Yes the beloved R-12 is "blend" of many different chemicals. I believe you mean Freeze 12 is an azetropic mixture as is many refrigerants used in daily life. Near azetropics mixtures are also mixtures of other refrigerants but must be charged in as a liquid due to fracterization of the refrigerant in vapor form. Near azetropics also have a temperature glide or will change state at 2 different temps. The new 410a is one such refrigerant.

Inquiring minds want to know.:silly:

Your splitting hairs here.
A blend is considered any refrigerant made up of 2 or more chemically different liquids.

Danny

An issue with blends is that the lightest components are likely to leak first. What is left in your system is an undefined component which does not perform as an efficient refrigerant. So a system charged with a blend that has leaked cannot be topped off to restore cooling but must be emptied and recharged completely to restore efficient cooling.

This may have been posted before but this thread is so ridiculously long that it is unlikely that anyone will read the whole thing.

R12 is CCl2F2. Like most refrigerants, it is not a blend. My point was simply that Freeze-12 is mostly R134a.

http://www.epatest.com/manual609.html#_TOC_8

Refrigerant Blends and System Retrofitting

Widespread research has been going on for replacements for CFC-12 and many other refrigerants. Refrigerant blends have entered the market and are currently being produced by many chemical companies.

Refrigerant blends are mixtures of refrigerant that have been formulated to provide a similar pressure/temperature relationship to the original refrigerant. Blends can be HCFC based, HFC based, or a combination of both. The HCFC-based blends are only interim CFC replacements because of their non-zero ODP. The HFC-based blends will be the long-term replacements for certain CFCs and HCFCs until researchers can find single refrigerants to replace them.

Many blends also use a flammable component (such as propane, or butane) as one of the components in the blend. Table 2 contains a list of common refrigerant blends, which have at least one flammable component, and are available on the market for stationary HVAC applications. Not all of these refrigerant blends have SNAP approval for use in automotive applications. Table 3 contains a list of the Motor Vehicle Air Conditioning Substitutes that have been approved for use in Motor Vehicle Air Conditioning (MVAC) applications. The refrigerants listed in Table 3 as "ASU" are acceptable for use in MVAC systems, while the refrigerants listed as "UNA" and refrigerants listed in Note 1 (that have not been submitted for SNAP review) are unacceptable for MVAC use. This SNAP approval does not mean that the alternative refrigerant is compatible with the materials (or lubricant) used in the MVAC system or that the performance of the unit will be similar. SNAP approval only means the environmental effects of the refrigerant are acceptable and the refrigerant has been tested to be non-flammable as blended and therefore the EPA will allow the use of this refrigerant in an MVA application. As part of the SNAP approval the refrigerants are tested to verify that the refrigerant as blended is not flammable. The EPA has made it illegal to use flammable refrigerants in motor vehicle air conditioning systems. Each potential new refrigerant must be tested according to the American Society of Testing Materials (ASTM) E-681 testing method to determine flammability. In addition to testing the refrigerant itself, if a blend contains a flammable component, the EPA requires leak testing to ensure that the composition does not change during a leak and become flammable.

The SNAP approval also includes a requirement for unique fittings to be installed on the high and low side service port of the system being retrofitted with the alternative refrigerant as well as unique fittings on the refrigerant cylinders which contain the alternative refrigerant. The unique fittings are part of an effort to minimize cross contamination. Table 4 lists the fittings for the SNAP approved MVAC refrigerants. Only SNAP approved refrigerant substitutes, that have been specifically approved for motor vehicle use, can be used in MVAC systems.

Some refrigerant blend manufacturers have chosen trademarks that may give the impression the "New" refrigerant is a drop-in for R-12 and have even incorporated the "12" as part of their name (FREEZE-12 for example). However using any substitute refrigerant requires as a minimum that the high-side and low-side service ports be changed to the SNAP designated fittings (Table 4) and the system be re-labeled to indicate the replacement refrigerant contained in the MVAC system. That means there are no refrigerants which can simply be charged into an CFC-12 or HFC-134a system without any hardware changes! There may also be other changes necessary such as new seals, hoses, lubricant, and additional safety devices. The EPA has several publications available on their Internet Site ( http://www.epa.gov/ozone/title6/609) or available from their HOTLINE (800-296-1996) which discuss compressor replacements, retrofit procedures, sources for retrofit training, and common Questions and Answers.

http://www.epatest.com/manual609.html#_TOC_8

Even though there are replacement blends on the market that will supposedly replace R-12 with minimal retrofitting, Mainstream is not aware of any automotive manufacturer to this date that has approved a refrigerant blend for an R-12 system. R-134a is recognized as the refrigerant of choice for new mobile air conditioning systems. There has also not been any single refrigerant or blend that is a direct drop-in for R-12 in automotive air conditioning systems. There is always the need for some retrofitting of the system. Finally, most blends and their lubricants are not compatible with the existing R-12 system and will require separate service equipment. Recharging a blend is also quite different, you must always recharge as a liquid.

There is a lot of misleading advertising concerning blends... many start with using " 12" in their name to give the impression it is compatible with R-12...
Then there are also dealers which will makes claims which leave out the necessary steps for a proper long life working changeover. Sometimes the non intuitive route is actually the cheapest and best in the long run... much reading and studying is necessary to find that out most of the time on something as complicated as our situations with these old MB AC systems existing in the modern world.

i definately concur.if your thinking of retrofit.study study study.:)

r-134a....no aroma?
 

just dropped by...read responses since my initial post. My situation remains the same. AC still blowing 38F. If I have a leak...it's slow or subject to external circumstances...all of which I haven't discovered as of yet. I didn't notice an aroma today. yesterday and the day before would be a yes.

I read on a different thread about MOLD being a possible problem. I believe a drain pan and lack of good ventilation may have been the culprits which allow mold to form.

Perhaps someone has some experience along this avenue?

MY 1992 used to live in a cooler climate....Bay AREA (calif). Just a guess, but my vehicle may not have had a lot of useage when up north. Now it's in South Calif....and the summer temps are a bigger concern.

Question: Mold collection in a cooler climate now evidenced when exposed to a higher ambient.....possibility?

Thanks all

ron_of_orange 12:06 PDT

"Perhaps someone has some experience along this avenue? "

If we had... it would be in the archives and accessed by hitting the search button at the top of the page... that is the fastest way to find most anything because otherwise you have to wait for the ones that know a particular answer to come on line...and then hope they will type out the answer again knowing it is already in the archives...
We have posted extensively about mold in the evaporator especially...

Freeze-12 Questions
 

After reading the preceding flame war, I'm a little hesitant to post, but here goes...

I have an inadequately cooling system in my 85 W126 which the previous owner had professionally converted 9 years ago from R12 to R134A. I'll spare you the details, but I have checked blend flaps, refrigerant charge, aux cooling fan, high/low pressures, etc. and everything is in check, but it's just not as cold as an R12 system. at about 95 degrees ambient, I get 58 degrees at the vent when moving, and about 70 degrees when idling. I do a lot of stop-and-go driving and this just isn't cutting it. And if anyone opens a door and lets some hot air in, it might be another half hour before it's cool again. On the highway the performance is much better, but again on a 95 degree day I would just call it "adequate" for the front-seat passengers (rear seat passengers complain that it's not cool enough, even on the highway).

I know the merits of converting back to R12 and plan on doing that eventually, but in the meantime I am interested in trying Freeze-12. I plan on having the existing R134A professionally reclaimed and would use the appropriate sticker and fittings. I would pull a vacuum before charging.

Here are my questions: Where can I get Freeze-12 in the DFW area? Is Freeze-12 compatible with the PAG oil currently in the system? Everything I read talks about compatibility with mineral oil but says nothing about PAG. I would tend to think it would be OK since Freeze-12 is actually composed of 80% R134A, but maybe someone with experience can tell me. After charging, would I just attempt to duplicate the recommended R12 system pressures? And finally, can anyone here confirm that it will get colder than R134A? I know my system was designed for R12 and that R12 will produce the best (read: coldest) results - would Freeze-12 yield results somewhere between R12 and R134A?

If the Freeze-12 isn't compatible with PAG, and I have to open the system and flush the oil anyway, then I'll just go back to R12. Either way, anything's better than the 58 degrees I'm getting right now (my 300E with original R12 system consistently gets 38 degrees - I have been measuring vent temps on all my cars for the past couple weeks).

a 40 degree drop or difference between ambient and vent temp is normal and anything more is asking for alot out of any a/c. measure vent temps/ambient in any central home hvac unit for an example.

all this talk about 38 degree vent temps...the fsm says 48 degree vent temps and anything lower than 41-42 they say to check the evap temp sensor for proper function so as not to freeze up or flood the evap. the ets is supposed to signal the comp when evap temp gets too low to cut off. the fsm also says at 104 ambient 68 vent temp is normal (of course humidity plays into this also). on low fan the vent temps drop cause evap has chance to build up. at high fan speeds air is moving accross faster and it is playing catch up.

the main plus with R12 is using mineral oil which is the most superior in terms of lubrication and less moisture absorption. the R12/mineral oil is/was a great combo!

the W126 has alot more cabin area to cool than a W124, is your console rear vent working? i have noticed the same as you on mine. my 1993 134a oe has 2 aux fans and a bigger/diff design condenser.

might consider a 35% light transmission or less 3M window tint job. vac/clean/comb condenser, remove blower motor and do the same for evap.

Thanks for the tips. I'm with you - 40 degree difference is quite an accomplishment but then it really doesn't seem sufficient. And my other car (W124) really does blow 38 degrees, regardless of what FSM manual says. I want that in my W126! I recently tinted front and rear with 20% light transmission, and fixed the rear vent to blow A/C; both have really helped but it's still not good enough. Condensor is clean, but I have no clue about the evap. Is it hard to clean it and/or can I cause a leak by disturbing something so fragile? How do I go about doing this?

I will say that the volume of air coming out of the vents is almost nil, even at high setting. With blower on high, if I hold my hand a foot away from the vent I can just barely feel air blowing on it. In the back seat the air is definitely stagnant and hot. Could my evap need cleaning?

I'm still looking at refrigeration because the "cool" suction hose really isn't all that cold and it doesn't even sweat. I know this is not normal, and I attribute it to the R134A which the system just wasn't designed for.

Any thoughts on Freeze-12 mixing with PAG oil?

"the main plus with R12 is using mineral oil which is the most superior in terms of lubrication and less moisture absorption. the R12/mineral oil is/was a great combo!"--James L

That is a particularly important point for most of the people here on this forum... because most of us have the Delco Scotch Yoke four piston compressor...

WHICH DOES NOT HAVE AN OIL SUMP....
( the old York does )

So the only lubrication it gets is what is taken around the AC system by being mixable with the refrigerant...

Something a lot of refrigerants don't do as well.... so this is an important point in addition to it being the more efficient molecule with regards to cooling....

gmercoleza ,
The symptoms you describe could easily be caused by blocked fins in your evaporator... a pain to get to and clean ... but at some point the only thing to do to help the system ...

leathermang, you think 58 degrees is acceptable under the conditions I described? I agree, if the volume of air was 2 or 3 times greater, I would probably be happy.

The average home window unit is expected to put out air at about 6-8 degrees under the temperature which it takes in...
You don't want the actual temperature in your cabin at 58 degrees... so if your system had the ability to take your ambient air to 70 quickly for instance you would probably be happy... so the total volumn capacity is what you are needing.. which can easily be an obstructed evaporator ...

Anyone have an opinion of ester oil vs mineral? I bought mineral and planned to buy a single
application vial of UV dye, but can't find any locally.

The guys at Carlisle Auto Air suggested ester premixed with UV dye, and I found
a couple of brands localy (including Castrol) but I wanted to pulse the board before proceeding.

Opinions please?

Actually that was a quote from James L. in my post....

Those guys at Carlisle have been doing this for decades... when I try to go overboard on stuff they talk me out of buying stuff...
As a result of those types of things I pretty much trust them...
Right before I actually start to do something to my AC system I call them for the final word....

i used the castrol mineral oil form ackits.com. ester and pag do not work as well with R12 as mineral oil and certainly do not mix well. freeze 12 is mostly 134a so that is what you have now.

to clean the evap (W126), remove blower motor (clean and lube it while it is out), i then used a 1 1/4 inch hose w/ shop vac thru the opening (you can feel with hand), then blew in comp air, also used a leaf blower thru middle dash vent (open). then used ackti foam green non-acid evap cleaner/degreaser, (use hand sprayer thru blower motor or hudson type sprayer). make sure your drain works and use towels as drop cloths., let sit then spray with garden hose connected to a vinyl hose to rinse, you can also use a brush or fin comb taped to a flexable stick like on a mini blind (use string or something so as not to drop down into no mans lands). i did mine and i could feel a difference.

Cool, sounds like something I should try. Where's the blower motor and is it easy to remove? Do I need to remove anything else to access the entire length of the evap? I'm guessing the hole from the blower isn't very large...

gmercoleza,
Do a search for Dmorrison's posts ( in your area no less ) ... he has done a great pictorial on getting to the evaporator... and his evap was about 50 percent blocked on the fins...
In those threads are also discussions of cleaning it without taking the whole dash out.. ( listed as about 17 hours in the flat rate manual YIKES !!)

under passenger side knee cover (remove knee cover under glove box), then the blower cover panel screws, remove blower motor screws and then remove blower motor downward, opening is about as wide as three knuckles, you will have cuts and scars on right hand! have fun!

Low Blower Speed
 

1984 300d Turbo 139k
Check The Voltage Output Of Alternator When A/c Blower On Max Replace Regulator Brushes On Back Of Alternator $28.50 2 Bolts 15 Min Done Diy From **************.com 13.5 Volts Plus Volts At
Battery Also Check The Front Radiator Fan Working Short The 2 Wires At The Rec Dryer And Ign Sw On **************.com Have Brush Kit For Blower Motor With Guide Book, Dieselgiant.com Have
The Freeze 12 Kit And Other Kits

A/C leak detection
 

I recently replaced my 1983 300SD A/C compressor . Diesel Giant's A/C page was very helpful .
The system held a vacuum a long time so I thought it had no leaks . Anyway the A/C cooling lessened over time and after about 3 weeks got to the point where the compressor won't activate . I assume that the refrigerant is gone ( Freeze 12) . At this point I think it it is time for some UV dye . Would it be okay to use that R134 / dye mix in a can from Autozone just for the leak test (I have adapters for this) ? Any other suggestions on how toi deal with this ? - Thanks

http://www.aircondition.com/tech/questions/19/What-are-the-Benifits-of-Leak-Testing-with-Nitrogen%3F

"It has neither the problems nor shortcomings of dye. "

Laws of Physics are difficult to get around but it seems that fish strories, fuel mileage, and vent temps often manage to do so.:)

There is a direct correlation between low side pressure and evaporator temperature. Check the vapor/pressure chart and read about subcool and superheat. At any given pressure there is a corresponding temperature at which the refrigerant changes from a liquid to a gas.

Higher outside temps mean higher condenser temps and higher pressures. Higher pressures mean higher evaporator temps.

I checked my vent temps yesterday against the outside air temps (94F). On high fan it ran 48-54. On low fan it hit 45 mometarily but I think that was just due to lag when I changed the fan setting. This was not comfortable, I wanted to turn it down, I was cold.

My car had been parked in the shade all day and it rained a little in the afternoon, cooling the car even more. When the sun shines on your car all day the temps inside are probably 120-130. The pavement is probably just as hot. You can't expect the AC to catch up very quickly.

I have had thoughts of running a total loss irrigation system for my condenser in extreme high heat. Instead we are packing to go back to Maine after the 4th.

Pump the water from the evaporator up there.

That's the truth. Six months ago, I had 20 degree air coming out of my vents. In the "EC" mode, no less. Claims of low vent temps are meaningless when not accompanied by ambient temperatures. And even then, they are subject to the "fish story" phenomenon.

Leatherman
 

The old york compressor, like in my W115, you say has an oil sump? If so, is there a drain and filler area? Where would this be? Also, I've heard these yorks a a lot more heavy duty than the delco R4 in the W123. Dealer told me these old yorks have no problem running R134 if I ever wanted to go that route. Any truth to any of this?

Kyle, One of the advantages to manufacturers of using the Delco pancake compressor is that it can be mounted in any position...
The York can only be mounted in two positions...
The MB AC manual for our cars shows how to make a bent DIPSTICK for measureing that sump oil... it is a rod with markings on both ends... one end for horizontal mounting and one upright...
It is my impression also that that York P piston is much stronger than our Delcos... whether that comes from always having the oil available from the sump I don't know... but certainly with anyone using other than R12 the oil movement is suspect for the Delco.
The disadvantage is that they are much rougher due to the weight and movement of those two pistons together rather than four smaller pistons with the movement spread out over the full rotation. It is also my impression that the York takes more HP to run...

I am looking at a complete rebuild of my system. I am not going to get a liscence so that I can buy the r12. So would this york you're mentioning work in place of my delco?

If I am going to have to use the r134a, I want a compressor that I wont have to change out every couple of years.

The York is usually mounted top front right on the MB's that I have seen it on...
It has a heavy mounting weldment.
If you are good enough at fabricating and hose building to be able to mount the York then you could easily mount one of the more standard type round compressors which are the size and shape of starter motor... this would provide the extra strength without the excess size and vibrations associated with the York... in other words... there are valid reasons why everyone switched over from the York 2 piston type to 4-6 piston swash plate style compressors....these later styles have oil sumps but fit along the engine with less hassle than the York style.
Changing out the compressor style would be 1000 times more work than taking the OPEN book $20 epa test so you could just buy and use R-12.
Do you feel you could not pass the online test ?
If you change to the other style compressor I hope you will take good pictures and notes and post them... a lot of people would like to do that.

Sure I could, it's the principal of the issue.

I shouldnt even own a $1000 benz if i cant pass the test. Otherwise, I'ld better be extremely well off to afford to have a shop do everything for me.

One other question, What are the compatibility issues of R12 and R134a? is it that the Lubricants react? Do the refrigerants react with the others lubricant? I understand the Legal and ethical reason (I have read this entire thread) but what keeps one from flushing an R12 or R134a system, to then use Synthetic lubricant and the refrigerant of choice? It seems that if the synthetic is non reactant with either refrigerant, just increasing the air flow across the condenser and using a parallel flow condenser would allow one to use R134a with cooler results (pun intended).

I know its like re-engineering the system slightly but it might be a better alternative to using "ozone depleting" (BS) R12 or using the toxic sludge R134a, depending on how you feel about it.

Yes, the lubricants react ( as far as I have read ).... seem to make a nice glob.

My control c-control-v keys are not working so I can not paste to here...and it wont let me use apostrophies either.. brings up search feature at bottom of page in Firefox.

Essentially there is nothing wrong with the course of action you describe. Take out all the R-12 lube, put in a good R134a lube , upgrade either fan or condensor or both ( and clean the fins on the evaporator inside your car )...
IF you use a synthetic which the R-134a will take around the system to keep your Delco lubed ( given its dependence on the oil movement due to lack of sump ) then ALL you have to worry about is the HIGHER head pressures... which MAY only affect worn Delco compressors.
Installing something like the Nippon or GM compressor would be a nice upgrade...

Since it appears that you do not consider the R-12 Ozone depleting why dont you just follow the rules about its use and have a car which is cool and comfortable at the least amount of work and money ?

If wanting to re engineer stuff was objectionable I would have been thrown out of several forums already.
Most things sold in this world have a balance between perfect and cost..which the manufacturer decides the line on... where I live I need a little more cooling than they did in Germany... and things get old... that is the time to put the extra into re engineering.. when you are already going to have the hassle and expense of replacing something anyway...