How do I replace A/C Receiver Drier on '81 300SD ? - PeachParts Mercedes-Benz Forum

Austin85 · #1 07-23-2009, 11:52 PM

I searched to no avail.

1981 300SD R12 system -

R12 is empty - this year - ( per my indy ) -> A/C was fine last year - so I figure there must be a leak....

He suggested before we do anything "drastic" we try replace the drier;

and pump in one of those 19.95 AC leak repair cans from WallyMart......

( I successfully repaired the leak in my 300E with one of these cans this week! )

And pump in new freon to see if it holds the charge ......Bill $200.

I am looking for any DIY on how to replace my own 81 SD receiver drier

if someone has done this before. Any tips very welcome.

AA

Ken300D · #2 07-24-2009, 04:34 AM

You won't find R-12 at Wal-Mart. You'll have to go to EBay and the seller may require a EPA certification. Don't mix the R-134a from Wal-Mart with the R-12 system.

In my opinion, the receiver/dryer is one of the least likely places to have a leak. You are much more likely to leak from one of the two shrader valves (input ports) or from the compressor.

dannym · #3 07-24-2009, 07:51 AM

What you should have done is put a can of dye in the system and charged it with nitrogen. Then you use a UV light to search for the leak. This should have only cost you a few dollars.
Your Indy should have told you this. He should also have told you not to use the leak seal stuff. From what I've read I'm not too impressed with your Indy.

Quote:

He suggested before we do anything "drastic" we try replace the drier;

That is drastic. These things aren't cheap and it will need to be replaced again after you find and repair the leak. You should have found and repaired the leak first then replace the dryer.

The first place I would look for a leak is the expansion valve.

To answer your original question. To replace the receiver dryer the refrigerant charge has to be removed. Then you just disconnect the 2 lines going to it and unlpug the wires going to the switches. Remember which one you took them off of. Then you just pull it out.
Put the switches on the new dryer with new o-rings and preferably nylog. Installation is reverse of removal.

Danny

Rooster300SD · #4 07-24-2009, 09:02 AM

I second replacing the schrader valves.
I just did the AC on my 84 300SD including
flush and a good vacuum which held. I lost all
my R12 through the high side Schrader valve
after charging, though. Leaking under vacuum
and leaking under pressure can be two different things.

After replacing the valve, all has been well and
I'm getting 45 degrees in 100 heat.

I replaced the expansion valve as well and it is
a royal pain to do on the SD, believe me.
I had to take an angle grinder to a wrench to
finish the job. If it's not leaking, I'd leave it alone.

Jeff

tangofox007 · #5 07-24-2009, 09:14 AM

Quote:

Originally Posted by Austin85

He suggested before we do anything "drastic" we try replace the drier;

That's sort of like replacing your lug bolts because you have a flat tire.

leathermang · #6 07-24-2009, 02:29 PM

Most people who deal with AC systems try to avoid dye...
for one thing it can clog a txvalve or other stuff...
AND it is pretty much worthless for a leak in the evaporator ( which my wagon had ) and other hard to reach or topside leaks.....
The more reliable way without any chances of bad consequences due to the testing procedure it to pressurize with nitrogen and four ounces of R22..
this can be detected by an electronic sniffer... then it can be legally vented as per EPA regulations.
When you have the whole system apart putting in new orings the schraeder valves certainly would be prudent to change out... since many are likely the original that came with the car.. cheap, good insurance...
But to think that a receiver dryer has any chance of being the leak is worse than buying a lottery ticket for odds.
No offense to your mechanic but he does not sound like he is really up on AC work...which may end up costing you a LOT of money in the long run...

#7 07-24-2009, 07:32 PM

As far as I'm concerned those leak sealant cans should be illegal to sell. If not illegal to sell, at least illegal to sell without a sufficient WARNING label.

Once leak sealant is in your system there is no shop that will touch it. The sealant will destroy their recycle/recovery machines and it's illegal for them to work on it without proper recovery.

A few weeks ago someone brought me a car that had one of these miracle in a can rip off kits already in it. I will give him credit, he was honest and told me that the crap was in there. Had he brought me the car BEFORE buying the death of his a/c system for $19.95 I might could have fixed it for not much money.

STAY AWAY FROM SEALANTS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If you refuse to stay away from them at least BE HONEST! Don't be angry at someone because they won't risk their recycle machine. They are just trying to put beans on the table and shoes on the baby like everyone else.

STAY AWAY FROM SEALANTS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Austin85 · #8 07-25-2009, 10:13 AM

I'll tell him these things.

1st- The leak stop issues !

2nd that we need to check for leaks. He was suggesting changing the the rec. drier because it is original and describer this as the filter of contaminants in the system....( Like the liver of the system..)

3rd....ask about replacing the valves & o-rings.........

I have a hunch these might be the issues........Thanks.AA

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