BrettStrikes

I ordered an front A/C expansion valve from 928 specialists and just noticed a 134A sticker on it. Is there a difference between an R12 expansion valve and one for 134? The part appears to be the exact same thing I have now which is an original valve utilized for R12. I was wondering if the internals were different. I plan on keeping R-12 and hope I can use the new valve and not order another one. Thanks for the insight in advance

ROG100

No difference unless its the O rings maybe.
I hjave used the same expansion valve in both R12 & R134a systems.
You cars A/C system was designed for R12 so stick with it as you will get better overall performance from it.
Let me know if you have any problems getting R12.
Its readily available at Napa and Pepboys at about $20 a can.
However you need a Cert to buy it.

dr bob

There are some differences, but finding a valve for R-12 is a chore these days. The R-134a valve will be fine. Seems there's a little less penealty going with the R-134a valve with R12 than going the other way. R-134a needs a bit more flow to get the same level of cooling, especially when the suction pressure is elevated (same as: Hot Day). Difference isn't big enough to worry about flooding the compressor with liq R12, that's for sure.

The valves in my S4 are common to several late BMW models, a fact that keep the replacement price competitive. Nice having the same system vendor "share" components like this among several customers.

BrettStrikes

It was great to only pay 29 bucks for the thing

ColinB

R12 has been illegal here for several years but was still available on the black market until recently. Now though, even that supply has dried up. At some stage when my R12 leaks away I will have to do the same conversion to R134a as I have already done with my VW Microbus. I can honestly say that I noticed no difference to that car after the conversion. Possibly the compressor ran a little longer each time it cut in but the air temperature felt the same. The VW conversion was quite cheap and only required new gas, oil, dye, dryer tower and fill valves. Anybody know what's needed for the 928?

Colin. 89GT.

dr bob

Colin:

Same stuff, plus you'll want to replace the o-rings in the system, and probably update at least the front hoses to barrier type. New expansion valves will help some with hot-hot day performance. Drain tthe old oil out of the comressor before you put the new stuff in. You'll be good to go!

UKKid35

Or you could just use a drop in replacement like R24 or Isceon49 which I have been using for the last three years.

toofast928

BrettStrikes,
Yes their is a difference between 134a and R12 expansion valve. The 134a has bigger orifices, it will allow more freon to flow and making the cabin too cold. The evap core will freeze after 1 hr of driving. Their is R12 substitute available at parts stores.
It's not a job you want to do twice....like I did.

ROG100

toofast928,
So there is a difference? How do you differentiate one from the other?
928 Specialists list one part number. You learn something new about these cars everyday.
My GTS is 134a from the factory and I fitted the same expansion valve to it that I did to my 82 Weissach which is R12.

I would not recommend any substitute, this will contaminate the system to the effect that no one will work on it as they cannot recover the substitute freon without special equipment.

Bill Ball

R12 substitute? Watch out!
http://www.popularmechanics.com/scie...tml?page=3&c=y

ColinB

Gents.Especially Bob.
Thanks for the info.

Colin. 89GT

BrettStrikes

I was under the assumption that an expansion valve will stop the flow so the freon reaches a proper boiling point to cool properly. Based on this assumption bigger orifices and more flow will decrease the effectiveness of the freon. An open expansion valve, or one not working properly which allows freon to flow frrely, is not as effective as a working expansion valve which restricts the flow to a certain point and lets it release. I could be wrong but I believe an expansion valve works best while restricting freon and not letting it flow freely.

toofast928

The valve says R-12 on it, just like the R-134a. I picked up mine at 928 International.
My system is still R-12 as I have a few pounders left. I herd one can use 134a in the R12 system with no conversion but I never tried.
I know a few shops that use a R12 replacement. "Cool Air" I think is one brand. But again I never tried the stuff.

dr bob

Running R-134a in an unmodified R12 system is slow suicide for the compressor. The mineral oil used in R12 systems for lubrication turns to jelly and isn't circulated in R-134a. No oil circulation equals no compressor lubrication, plus the congealed oil will partially plug things as it slimes its way around in there.