Thaddeus

I've converted 2 cars in the past... a couple of volvos. Those kits worked well.

Can they be used on 928's without replacing everything under the sun first?

I searched, and it's clear many people have done it... but I'd like instructions...

2V4V

Thaddeus,

You can swap over to 134a. You will need the appropriate (new) o-rings. make sure you have newer hoses (barrier style) which you already should. Also need to get the old oil out and the new oil in.

No complete kit that I'm aware of, just do the calcs and weigh carefully- 134a is much more sensitive to over/under charging than R12 was/is.

Greg

Richard S

I did the conversion to my 79 shark several years ago. Still works great. Anyway, I changed every seal, new expansion valve, new receiver/dryer, removed compressor and changed oil, removed condesor and cleaned extrerior fins. Re-installed everything, only hard part was the expansion valve, as the threads were bad on the original one. (Use a flare wrench.) I'm sure it is much more involved for dual AC, but it was pretty straight-forward for me (1st time BTW). If you have done this before, you should have no problem. Workshop manuals show location of each seal. Less than $200 total at the time, not bad since the AC hadn't worked for about 10 years!

Rich

UKKid35

Nobody has ever thanked me for suggesting this, but it's worked great for me

Drop In Replacement

Big Dave

I believe the process involves, at a minimum:

1. Evacuating the remaining R-12 in your system
2. Replacing all o-rings with the green o-rings that are R-134 compatible (but they'll work with R-12, too)
3. Draining the oil out of the compressor and replacing with either PAG oil or polyester oil. Polyester oil is compatible with the R-12 oil and is generally preferred.
4. Replace the receiver/drier (it's a must once the AC system is opened up). You can use the same drier for an R-12 or R-134 system, but it has to be a new one. Some suggest replacing the expansion valves at this point, too.
5. Vacuum down the entire AC system for at least two hours. Some recommend flushing the system first.

John Pirtle has a good write-up of the process:

Pirtle's R-134 conversion page

What seems to be missing is a list of the exact sizes of o-rings. I see he's got a partial list in his "email keepers" section, but I've never found anything that is a complete list (at least for pre-87 models).

The o-rings can be bought as a kit from 928 Specialists, but Jeanie thought a couple of the more expensive rings weren't included.

You'll find there's a fair amount of debate on this subject. A number of folks here have just added R-134 to their system with the polyester oil and experienced good results. Others will tell you that you're dooming your system if you do that.

Just make sure not to overcharge the system. Vacuuming helps prevent this. My AC worked for 3 days last summer after getting a recharge, but my helper either didn't vacuum it down properly or overcharged it....a seal burst and vented all the R-12 out within about 5 minutes.

Richard S

I removed the o-rings (seals) and took them with me to the parts store. We compared them to the replacement ones in stock to get the right sizes. Of course, I didn't bother to write any of the sizes down....sorry.

Rich

SteveG

Thaddeus: Is the present system compromised? Are sure you really want to do this?

Thaddeus

I don't know if it's compromised or not... I have a heater valve or other issue, and it blows hot all the time. I'm just assembling my plans long term... If the heater valve replacement fixes the overall behavior of the system, I may find the A/C works fine.

Bill Ball

In the US, at least, you need a refrig. tech license to purchase Autofrost. Looks like hoses might be an issue with small molecules except for late models. Seems not to offer any advantage over R12.

Randy V

Thanks.

Porsche930

Hi 928 enthusiasts,
I have recently posted a similar topic on R134 conversion at the Turbo board for my 930, one of the alternatives is a product called Duracool. Have any of you had any experience with it?

V-Fib

I thought I might muddy the waters just a little. You can become EPA Certified to service automotive systems. Download the manual and study, take the test on line (3 hours for 25 questions and you must score at least 21), pay the $19.99 fee and recieve your certification card to purchase any size container of R-12.
Epa approved 609 MVAC course
Just a thought.



Anthony Tate
79/928 Silver Metallic

touque

along the lines of what Anthony said, I certified at http://www.imaca.org/ about 6 weeks ago - it cost $15 and took about 15 minutes.

I also purchased some freon here: http://www.refrigerantsales.com/

You can definitely find it cheaper on e-bay if you're willing to wait, but these guys have shipping built into their prices and it arrived quickly.

John..

I replace the R/D and exp valve and dumped in the conversion oil and a couple of cans of R-134 A. That was 3 years ago and it is still working just fine. No O-ring change or oil change.

I have a spare compressor at home, so I just don't worry about it. If and when it stops, I will do the whole procedure.

Big Dave

John:

Did you use the stuff with leak sealant or plain R-134?