Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 09-29-2002, 01:02 PM
Registered User
Join Date: Jun 2002
Location: New Mexico
Posts: 31
Take control of your AC destiny with a DIY R134 replacement

Hi all,

Have been reading all the pros and cons of R134 conversion and have decided to do this myself. With AC being present in virtually all cars and refridgerant leakage an inevitability I wanted to decouple myself from having to depend on the local shop for this. It has been pointed out correctly that the cost of freon is still not too high but with a freon system you also get to pay for high shop labor anytime you need a charge from leakage or have any repairs done.

Also, the pricing of freon is kind of an unregulated wild-west situation in that there are no benchmark retail prices. If your local shop decides to raise the price 20% there is not much that can be done about it except a lot of calling around which is not very time productive. With retailers like WalMart selling R134, a pricing discipline is established that will allow the purchaser to know that the pricing is not arbitrary.

In order to prepare for this evolution I purchased the Haynes air conditioning and heating manual which is very good and will provide the basics needed to procede with confidence. I also purchased a manifold gage set for $100 which will be more than paid for by the labor saved.

Some have said that freon based cars don't make good candidates for conversion but I have talked to several people who are satisfied with their conversions, one in particular being a 450SL owner who finds adequate cooling here in New Mexico.

Reply With Quote
Old 09-30-2002, 06:40 AM
Posts: n/a
If you insist on converting to Freon 134 from Freon 12, that's all well and good. Although I don't convert them any more. I have converted several, some of which I have since converted BACK to Freon 12.

To begin with, the price of Freon 12 is actually falling due to the fact that the cars that require it are at least 10 years old, so they are hitting the wrecking yards every day in large numbers.

Freon 12 can be purchased for $29 per can or less with a 609 certification, which can be obtained by taking an online test for $15.

Steve Brotherton says it best when he states that R12 is the least expensive major component of your a/c system.

Many people are penny wise and pound foolish. They will spend scads of money to convert a system so they can use $5 per can Freon 134, instead of just repairing the leak, which must be repaired in any case and staying with $29 per can Freon 12.

All that said, regardless of which refrigerant you choose, you will need much more equipment than a set of gauges. You will also need a vacuum pump, a flush gun with solvent, and other various tools.

Don't even THINK about charging a system without evacuating first.

One more thing. I also bought a Haynes A/C manual. It is quite aged, and there is much that has been learned about Freon 134, it's lubricant compatibility and other things since it was written. Additionally there is some information in that book that is just plain WRONG. As an example, they are proponents of turning the refrigerant supply cylinder upside down and charging the system with liquid. This is a risky method that can ruin your compressor.

I would recommend that you throw it away or tear out the pages and use them to line the parakeets cage, and buy the manual available at or

You will also find the discussion forums at both of these sites to be extremely helpful.

Best of luck,
Reply With Quote
Old 09-30-2002, 12:56 PM
Keith Lucy
Posts: n/a
I recently converted from R12 to R134 and have a couple of questions.

1. I thought that R12 was illegal to sell, driving the price up because you had to "find" it?

2. Is there any difference between R134 and R134a?

Reply With Quote
Old 09-30-2002, 01:32 PM
jbaj007's Avatar
Registered User
Join Date: Jun 2001
Location: Santa Monica, CA
Posts: 2,053
R12 is very much for sale. Just need a 609(MVAC) cert. A 608 (HVAC) cert. will allow you to buy it also.

R 134a is the final product that is for sale. R134 is just an easy way to refer to it and may or may not have been a "beta" molecule for R134a. (who knows what Dupont was doing then).

You've already got gauges; get the 609 cert. online (easy) and have a shop pull the vacuum or rent/buy a vacuum pump. You can pressure test for leaks (static) with R134a (but the you would have to have it evacuated) or use Hydrocarbon refrig.(evacuate to your BBQ) for leak test. Then change receiver/dryer, evaluate oil supply based on size of leak(or flush and start fresh), pull vacuum and recharge with R12.
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 09:43 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page