Help flushing AC system.. Of coures I searched..Please help.. - PeachParts Mercedes-Benz Forum

jay3000 · #1 07-11-2003, 09:28 AM

Well my AC sytem is in a in a world of crap...To say the least.

To make a long story short (it's still long), I have no history on the car other than the fact that the person the worked on the AC previous to my ownership was a friggin idiot..

Went to evacuate, and re-charge the system yesterday.. The gauge (high, and low)readings were initially WAY to high, so we figured the system was overcharged. 50, and 400 or so.. At least it doesn't leak.

Before trying to recover the refrigerant, we took a sample, and the machine showed it to be about 50/50 r-12, and 134a.. All of the fittings were original r-12 type, and no stickers anywhere..

Now what do we do???? Was the question we both asked.

We decided to take a long shot.. evacuate, and recharge with 134A, (about 80%) and a little 134a compatible oil..With 93* outside, the best vent temps we could get was about 64*..

So I said.. Just suck the ***** back out, and I'll fix it like it should be.. After all, who knows what's in there now, could be half full of two different types of oil..

My plan is to flush the sysytem, replace the dryer, and charge with r-12.

I'm purchasing a flush gun from from ackits.. My question is, where are the best places to open the system, and flush?????

Obviously, I will have to remove the compressor, and the dryer.. Where else will I need to open the system to flush this thing????

Also, what other parts will I need???

Thanks in advance for any help..
Jay

#2 07-11-2003, 10:32 AM

Your pressures were so high, that I expect it was overcharged with 134 added to the 12. The idiots that do these things should be hauled off and castrated.

Just for your future reference, when an expansion valve is stuck or the system is otherwise fully restricted BOTH high and low sides go down, with the low usually going to a vacuum.

To get this thing right you need to break all connections and flush thoroughly to remove all the old oil. Replace the o-rings and use nylog to help them seal. Remove the compressor and flush it out several times with mineral oil, don't use solvent in the compressor. Make sure you blow ALL the flush agent out of the individual components.

Put in the specified amount of mineral oil and it doesn't hurt to put a little in the evap, some more in the condensor and a little in the compressor to total the volume needed.

Last thing before closing it up put in a new receiver dryer. Evacuate the system thoroughly and charge with R12.

You shouldn't have to purchase anything but o-rings, nylog, flush gun, flush agent and receiver dryer and R12.

Once you're done, feel proud of yourself for saving another good a/c system from one of these knuckleheads that will put anything in the system and not care about the consequences.

Good luck,

jay3000 · #3 07-11-2003, 10:47 AM

Thanks for the help Larry.. I guess there's nothing pretty about it.. Just have to do it..

I'll post back with results.. Won't be tomorrow though..

This forum Rocks

Zoonhollis · #4 07-11-2003, 03:59 PM

I am flushing my R-12 system for the second time because I did not heed LarryBible's mantra about flushing, flushing, FLUSHING.

In addition to Larry's fine suggestions above, I'd like to emphasize the importance of flushing the condensor, especially if the compressor was seized previously (which in your case it presumably was not). In my case, I removed the condensor, and upon shaking it vigorously, found that it was stupid with debris! It sounded like one of those Brazilian rain sticks you find in the Nature store in the mall. I don't think I could have flushed it adequately without removing it either. I ended up dumping a whole can of brake cleaner in (not all at once), swishing it around, and then blowing out again. You should have seen the detritus that exited the condensor and is now plastered on the side of my garage!

Also, I cannot stress enough the need to wear safety goggles when doing this. I was remiss in wearing mine, and I ended up with brake cleaner in my left eye. Fortunately, I had cold water nearby and I was dowsing my eye within 10 seconds. Scary stuff.

...sorry, I'm digressing somewhat.

jay3000 · #5 07-13-2003, 09:19 AM

How in the world do I flush the evaporator????? What do I have to take loose?? How do I get at it??

#6 07-13-2003, 09:31 AM

To flush your evaporator, remove the expansion valve and flush through it thoroughly. If you are flushing because of a failed compressor, you will have to flush, flush, flush, flush....... If you are flushing to remove all the oil to change refrigerants you don't need to be as dilligent.

When flushing the system, BREAK ALL CONNECTIONS AND FLUSH EVERYWHERE.

Good luck,

jay3000 · #7 07-13-2003, 08:57 PM

Thanks Larry.. I think I have it all figured out.. The good news is that the compressor has been replaced, and is at lest as new as 1997.. When this is all over Larry, I probably owe you some money.. Do you have a paypal account???

The other good news.. I just bought that 30 gallon compressor that's been on my list for years

I owe a bunch of folks on this forum some money, or something.. I'd be a poor man if it weren't for the help of the people here..

#8 07-14-2003, 07:31 AM

Glad to help. Keep us posted regarding end result.

Have a great day,

jay3000 · #9 07-15-2003, 09:54 PM

Removed the compressor, and the good news is that it's at least as new as 1998.. There is a sticker on it with punch out dates that ranges from 98 to 02.. Nothing was punched out, and the compressor feels good and smooth..

I'm still waiting on my flush gun to arrive from ACKITS.COM..

With a little bit of agravation, I managed to remove the expansion valve, only to find out that it clearly says R-134a on it..

I guess at this point, I need to order the one for r-12..

I'm still a little confused as to why it didn't work a little better when we evacuated, and re-charged with 134a.. we put in what had to be close to the correct amount??? System calls for 2.9 lbs or r-12.. we put 2.45 lbs of 134a..

I haven't found a huge amount of oil in the system, and it doesn't appear very dirty inside at all.. Fact is, I'm not finding anything wrong, and that's starting to bother me..

One thing I do know is that it does look the original receiver dryer.. Could that make that much difference???

Larry, what would your best guess be at this point??? I know your guess is only as good as the info I've provided.. I can send you a waiver to sign

Give me guidance...

Thanks
Jay

josev · #10 07-15-2003, 10:12 PM

when we evacuated, and re-charged with 134a.. we put in what had to be close to the correct amount??? System calls for 2.9 lbs or r-12.. we put 2.45 lbs of 134a..

you had to much r134a r134a has a higher pressure so u only need about 1 1/2 pounds of it if i'm not mistaken
also with r134a your aux fans come in a little sooner than
when you run r12 unless you change the pressure switch at the receiver dryer.enjoy

#11 07-16-2003, 10:12 AM

I have no way of knowing much until you evacuate, charge and check pressures and vent temp.

The r/d would not cause the system not to cool unless it were plugged up. It would be a good idea to replace it. Since you are flushing, you will be able to get the correct amount of oil in the system. Just because you saw very little oil does not mean that it was low. The oil is distributed and sometimes certain parts will be dry.

Good luck,

md21722 · #12 07-17-2003, 10:18 AM

I used a flush gun to flush the evaporator on my '87 300D (W124) last night. A little bit of green came out and then the color of the flush, and then clear. The clear line I hooked to the evap to catch the exit flush never was completely dry. Always a little on the outer edge of the hose, but clear. Even running dry nitrogen thru the evap it did not get "dry" in the exit flush hose. Is this Okay?

What is the recommended way to flush the metal lines to the evaporator? The smaller one that has a piece of Aeroquip hose in the middle comes out of the car easily. But the larger line does not look so easy to remove or get the flush get into.

I plan to to flush the manifold hose with the flush gun and then remove the compressor and pour mineral oil into it and turn it by hand and dump out repeatedly until the green dye is all gone.

The reason for this work is the system was opened when a deer wacked the car a few months ago. (I'm not repairing a Black Death compressor problem.)

Thanks,

jay3000 · #13 07-21-2003, 08:38 AM

I completely flushed the system, clean as a whistle.. Flushed the compressor with oil. Replaced all of the o-rings, and used nylog.. Replaced the receiver/drier..Added 8 ounces of synthetic oil. Vacuumed the system for 45 minutes or so.., and finally re-charged with 4 cans of virgin r-12.. According to the label under the hood system capacity is 2.9 lbs..

Vent temps are still not cold..

Ambient temp 82*
humidity--- very
vent temps-- about 60*
Engine rpm 1500
High side 225 or so
low side 33
Electric fan works fine
Compressor does not cycle off.. Runs all of the time..

I'm lost.

The return line is cool, but certainly not particularly cold.. What in the world could I be overlooking????