300D AC Charging - Help! - PeachParts Mercedes-Benz Forum

tobybul · #1 06-01-2006, 06:03 PM

Looking for the low and high side fittings to connect charging line to. Where is it. The picuter in the online svc manual does not look the same as what I have. And yet they show it as the model.

I am going to use the NAPA R12 to 134A conversion kit. Just can't seem to find the fittings. Thanks in advance for the help.

1985 300SD Sady · #2 06-01-2006, 06:09 PM

Why do you feel you want to do a conversion?

What is wrong with your A/C system?

Why not pay someone to fill it up with R-12 and keep it stock as it was designed?

tobybul · #3 06-01-2006, 06:13 PM

Quote:

Originally Posted by 1985 300SD Sady

Why do you feel you want to do a conversion?

What is wrong with your A/C system?

Why not pay someone to fill it up with R-12 and keep it stock as it was designed?

I just got the car and I don't know when the AC last worked (not working now. had no belt and I put one in). It has some pressure in the system cuz I push the schader valve for quick second and something came out.

I don't have a gauge to chk how much pressure is in the system now. I thought i'd just charge it using the kit and see what happens.

tobybul · #4 06-01-2006, 06:22 PM

Quote:

Originally Posted by 1985 300SD Sady

Why not pay someone to fill it up with R-12 and keep it stock as it was designed?

Good question.... saving $$?? Plus this resource is running out.... and I talked to a couple of shops and all I'm hearing is $$$$$$$. I am afraid I'll be nickle and dimed. One even said its not unusual to end up with a $1000 bill just to get it going. Thats assuming everything works. Scaryyyyy.....

Motorhead · #5 06-01-2006, 06:38 PM

You don't say what yead 300D you are working with. Let us know that and then we may be able to help you.
If the BELT is off, I would be concerned that there could be more to it than just dis-charged. Is the compressor frozen? If not, does the clutch spin freely without noise?

With out knowing the history of the A/C on the car, you almost have to go to square one before you just charge it. If the compressor is not frozen up, I would put at least a belt on it and make sure that clutch bearings are ok by starting it and see if the clutch is noisy.
If the compressor isn't frozen, the clutch with a belt on it isn't noisy(bad bearing), Then have someone put a vacuum pump on the system and see if it holds a vacuum.
If all of the above check out ok then you could take a chance and charge it.

My .02 cents worth....... "Keep the HORSE in FRONT of the cart."

Find a member that may be close to where you live that has some A/C experience. I have the vacuum pump and gauges.... bought the pump used and it has paid for itself!

tobybul · #6 06-01-2006, 07:14 PM

Quote:

Originally Posted by Motorhead

You don't say what yead 300D you are working with. Is the compressor frozen? If not, does the clutch spin freely without noise?

If the compressor isn't frozen, the clutch with a belt on it isn't noisy(bad bearing), Then have someone put a vacuum pump on the system and see if it holds a vacuum.

Find a member that may be close to where you live that has some A/C experience. I have the vacuum pump and gauges.... bought the pump used and it has paid for itself!

1985 300D. I already put a belt on. Clutch is not siezed. Spins well and now with belt on turns good and no noise. I suspect system has very low charge per my comment above. Thats why not kicking in. Pressure switch not sensing pressure.

Where are the low & high side fittings??

Matt L · #7 06-01-2006, 07:22 PM

Don't add 134a without evacuating the R12. Take it any shop for that evacuation, then proceed with the conversion. You do not want to add 134a on top of any remaining R12.

They'll show you where the fittings live.

Furthermore, you really should remove any mineral oil left in the system. It might not hurt anything but your capacity, but it certainly wont do any lubricating with 134a in there.

A better option would be to get a license for twenty bucks (online) and buy some R12. You should add some oil too.

R12 isn't much more expensive than 134a, and it sure doesn't seem to be running out.

tobybul · #8 06-01-2006, 07:24 PM

Quote:

Originally Posted by Motorhead

Then have someone put a vacuum pump on the system and see if it holds a vacuum.
If all of the above check out ok then you could take a chance and charge it.

If there is pressure in the system, isn't this an indication that its holding its chege fairly well? And pulling vacumm may not be necessary anymore?

Matt L · #9 06-01-2006, 07:30 PM

Quote:

Originally Posted by tobybul

If there is pressure in the system, isn't this an indication that its holding its chege fairly well? And pulling vacumm may not be necessary anymore?

If there's R12 in the system, pulling a vacuum is ABSOLUTELY MANDATORY! It is imperative to remove all of the R12, unless you're adding R12 back to it, which is what I would highly recommend.

tobybul · #10 06-01-2006, 07:51 PM

Quote:

Originally Posted by Matt L

Don't add 134a without evacuating the R12. Take it any shop for that evacuation, then proceed with the conversion. You do not want to add 134a on top of any remaining R12.

They'll show you where the fittings live.

Furthermore, you really should remove any mineral oil left in the system. It might not hurt anything but your capacity, but it certainly wont do any lubricating with 134a in there.

A better option would be to get a license for twenty bucks (online) and buy some R12. You should add some oil too.

R12 isn't much more expensive than 134a, and it sure doesn't seem to be running out.

First, I've read this before that you could get license online. Haven't found the website yet. Who issues these?

2nd, the NAPA kit says its ok to use this kit with existing R12. Its suppose to be compatible and converts the system just by simply adding the new type of oil and the 134A.

tangofox007 · #11 06-01-2006, 08:28 PM

Quote:

Originally Posted by tobybul

First, I've read this before that you could get license online. Haven't found the website yet. Who issues these?

Look no further. Section 609 Certification is what you need. $15 here:
http://www.macsw.org/certification.php
Don't knock yourself out studying. The test is "open book." Using the "find on page" feature (ctrl F) you can finish the 25 question, multiple choice test in about an hour.

I recently bought 8 cans of R-12 on Ebay. Seller never asked for my certificate number. All he wanted was payment.

1985 300SD Sady · #12 06-01-2006, 08:39 PM

Matt L is right on the money, dont try looking the the cheap way out becuase usually it will end up being the more expensive one.

Ask me how I know.

Motorhead · #13 06-01-2006, 08:44 PM

Quote:

Originally Posted by tobybul

1985 300D.
Where are the low & high side fittings??

On the '83 I have in the yard and the '84 that my wife had, the LOW side fitting is about center between the radiator shroud and the engine. The HIGH side, for some stupid reason, is under the car on the right side of the engine.

tangofox007 · #14 06-01-2006, 08:48 PM

Quote:

Originally Posted by Motorhead

The HIGH side, for some stupid reason, is under the car on the right side of the engine.

Which is an excellent location for a high side valve. No telling how many lives it has saved, being located in an out-of-the-way place.

tobybul · #15 06-01-2006, 09:19 PM

Quote:

Originally Posted by Motorhead

On the '83 I have in the yard and the '84 that my wife had, the LOW side fitting is about center between the radiator shroud and the engine. The HIGH side, for some stupid reason, is under the car on the right side of the engine.

The low side fitting you are referring to must the schader (tire) valve almost right on top of the radiator hose just in front of the air filter cover. I thought thats just for testing the system and not nedcessary the low side fitting.