How easy is it to re-charge A/C on W124
 

Any details would be good. I have a slow leak, over winter and for the past 2 years in the Summer I do have A/C. So I take to the local MBZ shop and he re-charges. I thought I should do it.

Thanks,

Mike

A/C Recharge
 

If you havn't done this before you may wany to pick up a Chilton or Haynes Manual but it's really not too difficult.
1) Identify which type of Freon you have (R12 or R-134).. Usually the R-12 Freon cars have a fitting that looks like a tyre valve. The R-134 has a fitting that looks like a high pressure air or hydraulic fitting. Also look for identifying labels under the hood that will tell what type of Freon you have. Do not mix different Freons!!!
2) Identify the low pressure side of the system, Low pressure is coming from the evaporator side(under the dash) to the compressor, high side will be from the compressor to the condensing coil ( in front of the radiator).
3) do not connect to the high side unless with appropriate gauges
4) Hoping you have R-134 buy a refill kit at parts house (advance, Pep Boys, Auto Zone). R-12 now requires a technician permit to purchase unless you can find some aftermarket. The fill process is very similar.
5) With engine running and A/C on high add one 12 oz can until the A/C blows cold and the compressor stops cycling off and on.
Do not overfill, as soon as the compressor stops cycling-stop adding

6) Be very carefull to not contaminate your system with outside air, e.g. bleed some Freon out of the container into the refill line before you connect to your car system and have the can valve very slightely open when you connect and disconnect.
Good luck
Al

Try Amazon for the hayes manual, Automotive Heating and Air Conditioning Manual. I just picked up a used one on there for $3 which turned out to be brand new
.
Try Ebay for any r-12 or r-134 supplies you need. Lots of folks selling r-12 for about $20/can including the shipping. This one guy John, with an ebay store out of wisconsiin was very helpful in anwering all my dumb questions I had about this topic and helping me order the right stuff. Spent about 75$ total in r-12 parts and supplies to recharge my 126. Local guys wanted $280. Here's his Ebay store link.

http://stores.ebay.com/Frosty-Freeze-A-C-Products-Company

Actually, as you add freon, watch the little sight glass in the high side line. When you no longer see any bubbles, you know a solid stream of liquid is coming from the condenser and the system is properly charged.

At least with the R12 the system was designed for... Not sure about the sight glass method with R134A.

It sounds as if you are not an experinced refrigeration guy so it's important that I warn you.

Do NOT try to charge through the high side port! This can result in can explosion!

If you don't know how to identify the low side port, then stop, do some research and KNOW what you're doing.

You should use manifold gauges on this car. On some American cars the fittings are fool proofed to prevent incorrect connection. Your MB, however, has the same size ports on low and high.

I would strongly recommend that you do some reading and learn the principles of refrigeration, get correct equipment and be SURE of what you're doing before proceeding.

I have thought a few times that if any of our mshop friends were to get hurt or worse, we would probably never know about it, at least not in this lifetime. We would just stop seeing their posts.

Be safe,

Hay Larry: I know this is a difficult question to answer but what should the Low side read when fully charged.[Approx.]

I hope you're not trying to charge by monitoring the low side only.

The low side will fall somewhere around 30 and the high side will be around 250. This is assuming that you are very wisely still using R12.

There are many variables including ambient temp.

Good luck,

I have found the two nipples on my 1992 300D. One is new the driver's side headlight, which I think is the high side. The other near the fuse box which I think is the low side.

Can someone confirm?

Thanks.

Mike

That sounds right. The low side pipe is larger diameter than the high side. The low side will be cold if it's working. The high side is near the drier which has the sight glass on top. The high side will be hot if it's working.

At your own risk, of course....

BTW, to be legal you need to find and correct the leak.

Yes Larry I am still running r-12.I am in the process of finding a leak.

How long does it take to fill? I wanted about 20 minutes and only half of the can is gone?

Should go in in just a couple of minutes.

I assume you do have the engine running while you are charging? And the AC on? And the compressor is engaged?

You may need to put the can in warm water. The pressure drops as it cools.