RC, I know this isnt a ski related question but there are some HIGH Mechanicaly Inclined people on here that I hope can answer my question. Then Ill delete this post.

Guys I need to know when I convert the A/C system in my 93 Ford Ranger from the R-12 to R-134 do I really need to change the O-Rings in the system. I hear the new freion will eat at the old O-Rings.
Please help.
Mick

YES, hope thats not all your going to change out... the cost is reletivly inexpensive... just labor. Hoses should be fine, but change out that dryer.

NO

Who told you that Freon r134-a attacks o-rings?....it is BS. Ask them what about the seals in the compressor and the hose used all thru the system.

When R-134a was first introduced, it was thought that all non-barrier/nitrile hoses would have to be replaced during an a/c retrofit. Early laboratory tests showed that the small R-134a molecules leaked through the walls of non-barrier hoses more readily than the larger R-12 molecules did. In the lab, this caused unacceptably high leakage rates. More recent testing, however, has shown that oil used in automotive a/c systems is absorbed into the hose to create a natural barrier to R-134a permeation. In most cases, the R-12 system hoses will perform well, provided they are in good condition. Cracked or damaged hoses should always be replaced with barrier hoses.

Unless a fitting has been disturbed during the retrofit process,o-ring replacement should NOT be necessary. Most retrofit instructions call for lubricating replaced O-rings with mineral oil to provide this protection.

In early 80's and before that o-rings could swell and get soft from any oil and refrigerant... eventually.

I think it's more a question of pressure. R-134 runs at a higher pressure, therefore your older seals, hoses, ect, MIGHT blow.

Or maybe I've got it basacwards.

My friend changed to the new R-134 and he didnt change anything. He did it about a year before he sold his truck. Im thinking since I plan on selling my ranger in a few months ill be ok with just draining the oil in the compressor and adding the new frieon with new oil. What the heck the kit was only 30 bucks. I plan on changing the orfis sp too.
Thanks for you guys imput.
Mick

I am a GM tech and we only change the drier and expansion valve or orifice tube, all the seals and hoses should be fine unless there is a leak in the system comeing from a hose are a seal. Any time you open and a/c system to the outside enviroment as if to replace any one part of it the drier should allways be replaced it functions as a filter also. If you are worried about the seals they have a oil with the retro kit should have a conditioner in it for the seals and the r12 oil that makes the r12 oil equivilent to the r134 pag oil.

So dont drain the oil that is in the system? Just charge with the retro kit and go?

On a Ford, you MUST change the expansion valve, the drier, and flush the system before converting to R134. The lubricating oils in R12 and R134 are incompatible, and will destroy the seals if the system is not flushed before converting. The expansion valve must be changed due to the difference in viscosity between the two coolants. The drier must be changed for the reasons stated above regarding incompatible coolants.

I did this same thing on my Mustang, and everyone I talked to said this is the way to properly do it on a Ford. Total price was less than $500.

Maybe I should have been clearer on this. It is not freon R134a that is harsh on o-rings and seals but the oil used to lube the compressor. This problem was solved years ago so do not worry when retrofitting; with the proper oil it is a non-issue now.

R12 oil (mineral oil) will not mix with R134a and be circulated through the air conditioning system for lubrication.

This has been remedied by using synthetic oil.

PAG (Polyalkylene Glycol) oil is used by all original equipment manufacturers and is harsh on seals and gaskets.

Retrofit oil (Poyol Ester oil) is less harsh than PAG oil and can be used with R134a or R12 refrigerant.

I agree with LouisianaGP.
I recommend that you replace the orifice and drier...but if your not going to change the drier at least pull a vacuum with a high quality vac pump with new oil in it, over night. A high-prolonged vacuum will renew the desiccant (moisture boils at 29.9" then can be removed by the vac pump). This will NOT remove debris or oil. Make sure there are NO leaks before vacuuming system.

Hope this helps

Thanks guys.
I bought a new Orifice and Dryer. 37 something for both. I talked to the A/C shop down the road and they will evacuate the system to get all the old oil out for 20 bucks.
Should I put the new orifice and dryer in before I evacuate the system or wait till after? I dont think the system leaks. I guess Ill find out when I put a can or two in.
Mick

You can still get R-12. JCWhitney.com

Thanks guys.
I bought a new Orifice and Dryer. 37 something for both. I talked to the A/C shop down the road and they will evacuate the system to get all the old oil out for 20 bucks.
Should I put the new orifice and dryer in before I evacuate the system or wait till after? I dont think the system leaks. I guess Ill find out when I put a can or two in.
Mick