Unsuccessful attempt to recharge A/C - PeachParts Mercedes-Benz Forum

cewyattjr · #1 05-25-2007, 08:47 PM

OK, spent another half hour or so fiddling with this. I have one of those all in one trigger rechargers with the pressure meter on top. With the A/C "on," not in EC mode, I see almost no pressure when trying to recharge. When I switch it back to EC, I'm getting significantly more pressure in the line. Even appears as "charged" at that point, and I can feel pressure from the valve when I engage/disengage the charge connector.

Why would the line be more pressurized with the A/C off and drop when the compressor is supposed to be on? Symptom of a bum compressor?

When switching A/C, I can hear what sounds like a "click" under the hood, and I check the pressure, and it drops considerably and doesn't appear to be "taking" the charge.

Sure is hot today!

-Chuck

Knightrider966 · #2 05-25-2007, 08:55 PM

Your using the wrong AC fill system! Those all in one trigger unit's are junk. I've never gotten one to work yet, but they leak like a sieve. As far as your AC pump is concerned, you will not get the pump to come on unless you get some pressure into the system first. Your can of Refrigerant will turn cold when it is being inducted into the system properly. However, too much oil in your system will reduce it's effectiveness for cooling. This could be your problem since refrigerant leaks are usually gaseous and not liquid and refrigerant oil will remain oil even at atmospheric temps.

cewyattjr · #3 05-25-2007, 08:58 PM

So it fits the retro-fit add-on connector, but I should use a different fill type unit?

Knightrider966 · #4 05-25-2007, 09:07 PM

I have yet to find one of those pistol trigger dispensers to work right yet! But I have had the cap assembly blast off into space once with a big BANG! Get the hose that screws onto the top of the can, with the gauge if you like. It will help. When refrigerant is being sucked into your system, the can will go cold. The only other thing I've found is that sometimes the last person to do a conversion will not remove the Schrader valve in the original fitting and that can cause a recharge delay. You would have to remove the retrofit fitting first to find out, but try what I told you first. Try Phoenix for hot sometime! 103* in the shade so far this summer. It will get hotter!

cewyattjr · #5 05-26-2007, 10:02 AM

Quote:

Originally Posted by Knightrider966

Your using the wrong AC fill system! Those all in one trigger unit's are junk. I've never gotten one to work yet, but they leak like a sieve. As far as your AC pump is concerned, you will not get the pump to come on unless you get some pressure into the system first. Your can of Refrigerant will turn cold when it is being inducted into the system properly. However, too much oil in your system will reduce it's effectiveness for cooling. This could be your problem since refrigerant leaks are usually gaseous and not liquid and refrigerant oil will remain oil even at atmospheric temps.

That definitely did the trick! Thank you! Just got back from Autozone and put in two cans and things are cooling nicely now.

In the area of "second thoughts" -- the previous owner assured me that the R12 was evacuated. In case there is still oil from R12 in the system, what's the worst that could happen if you add the R134a? Lose the compressor over time, or is it potentially more volatile than that?

Thanks again for the advice, the simpler hose 'n tap worked perfectly, can got cold just as described and sucked right in there.

-Chuck

Knightrider966 · #6 05-26-2007, 01:10 PM

Quote:

Originally Posted by cewyattjr

That definitely did the trick! Thank you! Just got back from Autozone and put in two cans and things are cooling nicely now.

In the area of "second thoughts" -- the previous owner assured me that the R12 was evacuated. In case there is still oil from R12 in the system, what's the worst that could happen if you add the R134a? Lose the compressor over time, or is it potentially more volatile than that?

Thanks again for the advice, the simpler hose 'n tap worked perfectly, can got cold just as described and sucked right in there.

-Chuck

Great! glad I could help you! I remember the HUMID dog days of summer in New England. Air Conditioning was more of a moisture removal aid than actually cooling but even that makes a BIG difference. Carrameow, Interdynamics is made in China now and I would not recommend those if anything else is available! I got my set of manifold gauges from Napa and those are made by Stewart Warner! Now I know those are more expensive, but not that much more and they are worth it. you are not going to get the small 14 oz. cans of refrigerant to fit on the suction hose though. you will have to make your own adapter to get that to work, but everything you could need is available at any ACE hardware store and would do the trick. Not All of you guys will need the manifold gauges, but get good ones if you do! A good set will not be hard to recognise. I would go to NAPA, get AMERICAN made parts and make sure you are buying solid brass at the strees points where it matters, like the coupling connectors. Remember, when you retrofit to R134, your sight glass is useless when your close to the fill point. R134 works best when the system fills with about 10% less refrigerant than R12! R12 is going the way of the dinosaur, it is no longer being made and when it's gone it's gone. If your system is not working well on r134, which I hear a lot, it's because the system is NOT put on a vacuum pump for a complete purge and flushed properly! My dash vents are producing temps at 49* when it's 103* in the shade! At the least to properly fill your system, use compressed air to evacuate your condensor and evaperator of old refrigerant oil and you will notice a difference. In Phoenix, the air here is very dry and results will differ with climate changes and humidity. Good Luck and don't cook (in your car that is!) Have a great Memorial day and don't forget to thank a Veteran for your freedom! Many have paid the ultimate sacrifice, with their lives and we own them a debt of gratitude!

speace · #7 05-25-2007, 09:25 PM

Quote:

Originally Posted by cewyattjr

Why would the line be more pressurized with the A/C off and drop when the compressor is supposed to be on? Symptom of a bum compressor?

When switching A/C, I can hear what sounds like a "click" under the hood, and I check the pressure, and it drops considerably and doesn't appear to be "taking" the charge.

-Chuck

I'm not an A/C Pro, but have recharged several systems over the years. The pressure on the "low" side will most always increase when the compressor cuts out. Actually that is a good indicator that the compressor is working!
At rest, the high and low pressures will eventually equalize and the pressure will be more than the "normal" operating pressure for the "low" side. I use a "Manifold" type gauge set from Autozone that lets me see both the high and low sides.

Good Luck!

Regarding not "Taking" the charge: I would guess you don't have a good path from the can to the inlet valve. You will have to inspect all pieces of the charging kit. It could be the can isn't opening, the valve won't let the gas out, the hose isn't depressing the schroeder valve.