Well, I've given up until I can get some definitive answers. I evacuated the system and pulled a vacuum on it again. I tried to charge it with the car running and the compressor on. The low side went up to 130 this time and the high side was at 105 or so. It only drew in 7 ounces. I shut it down because it just seemed the low side pressure was too high.

I had the same issue when I charged my 260E. It would not pull in anything more than the first can. In the end, I had to run the car at 2000rpm with the can in hot water for it do it. Have you tried that?

I am not sure why your low side is higher than the high side though. Possible blockage at expansion valve?

Did you put in correct amount of oil to correct for replacement of RD? (not your cause, but side Q)

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Thanks for your reply.

The a/c unit has a "blanket" which heats the virgin cylinder, so there's no issue with a can freezing. The cylinder is pretty well heated.

The low side pressure seems to be my problem right now. Before my system lost enough refrigerant for the compressor to shut of it was in good operating condition. Looking back at it now, there were moments when it was intermittent, but that was more than likely because the refrigerant was slowly being lost via the pressure switch.

Could the loss of freon have caused a problem wth the expansion valve?

Yes, I replaced the oil.

Thank you.

I'm going to keep throwings things out there until something sticks. So, can the drier be part of the problem? I started this whole process last evening. I put a new drier in at that time, but the system was not left under vacuum overnight. I haven't opened the system after that drier was installed, but hasn't it been accumulating moisture all of this time?

If I should change the drier again I will as I have another new one. If I have to pull a longer vacuum on the system before attempting to charge it again I can do that also.

I just need some ideas here.

Thank you.

Recovery tank pressure is not what will keep it from charging from the tank. There is a float sensor in the tank and it will not release refrigerant from the tank until enough is in the tank for a charge. It will take several recoveries after tank preparation before you can charge from it.

Hope this helps.

Thanks for your help.

However, I do not want to charge from the recovery tank. I want to charge from the virgin tank of R134. There's a mode selector button on the unit which lets me choose "Charge Virgin"... So, that's what I've been attempting to do.

I went out this morning and pulled a vacuum on the system for an hour. Immediately after that hour was up I set the unit to charge the car's a/c system from the virgin tank of R134. This time it sucked in 1 pound of refrigerant. The low side pressure was 30 and the high was 200. The ambient temp was 85 degrees. The low pressure was actually all over the place at times. It went all the way up to 150 and dropped back down to between 30 and 40 rather quickly a number of times. I don't know if that's because of the pump going on and off or what.

If I shut the car off the low side goes to 70 and the high to 160. With the engine revving the low drops to 15 and the high up to 200. I can't get any more refrigerant in right now. I'm obviously getting there, but need that little push in the way of information as to what my next step should be.

The compressor turns on by itself now since there's a lb of R134 in the system. The vents blow cool, but not cold. I have to put 1 lb 6 oz more of refrigerant into the car.

Any help is appreciated.

revving at 1500 ...you need to get in the upper 30's for low side...then you will have cool air... high side is almost there....

congratulations on the progress made.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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Hey Lee: I had someone revving it up between 1500 and 2000 rpm. It just wouldn't draw in any more.

maybe try later in the day..... that seems to be working for you...

all kidding aside... i just don't have any other answers.... or the one i give you ....you may not like/

take it to an a/c guy and let him show you the final trick if there is one....

i think the key is that you are holding vaccuum and don't have leaks....

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

Yeah, I know I can always take it to someone tomorrow. However, the guys I've dealt with here don't want me hanging around while they do anything. They don't want to educate me so I can do it myself. So, just letting someone else do it doesn't get me the answers I need. We've all been begginers at some time. I just need to find out what the proper procedure is and I can take it from there.

Pulling the 1 hour vacuum seemed to have made the difference. I don't know. Maybe it was coincidental. I'll keep my eyes on this post today waiting for more answers.

Thanks for your help.

you are probably trying to draw gas off the top of the tank instead of charging carefully with liquid where the gas pressure is used to push the liquid in.[100psi gas pressure in tank and 30psi pressure on low side if you open valve it will flow to the lowest pressure]

__________________
David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

Hello: Thanks for your reply. I really don't know what you're referring to. The recovery/recharge unit I have can be set to do the charge automatically after the system is evacuated/vacuumed, or each function can be manually set one at a time. I tried it both ways.

The fact is, I finally got a complete charge of 39 ounces of R134 into my 1990 300SE. It's obviously a learning process for me. I held a vacuum on the system for one hour. Then, I immediately set the system to charge the 39 ounces of R134. The car's a/c system drew in 16 ounces in short order then stopped. So, I disconnected the hoses, evacuated them and hooked them up again. The system drew in another 7 ounces. I did that two more times (9 ounces, then 7 ounces) until the full 39 ounces were transferred into the car's a/c system.

I still don't know what I was doing wrong. I guess I'll figure it out one of these days.

The R134a provides reasonable cooling when it's not terribly hot here in Southern Florida. However, when the ambient temperature is above 85 degress, the fan has to be constantly on high or the cabin will become unbearable. I certainly want to convert the system back to R12 so that it can run as it was meant to. I'll start purchasing parts to do that soon.

strictly local driving in PBG will kill you....too much traffic there...

congratulatoins.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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