Are the Compressor Valves Replaced When Switching from R12 to R134?
 

A PO converted my '87 Carrera's AC from R12 to R134. There is a leak on the high pressure side outlet of the compressor in the engine bay. I've already replaced the schrader valve and it still leaks.

I guess what I'm asking is, is the part in the PET still accurate even though my car has been converted? That would be part 930-126-925-00 in the image below:

http://forums.pelicanparts.com/uploa...1530310864.png

R-134 have quick change connections. Those appear to be R-12.

You screw the gauge hoses on for R-12.

You also screw the R-134 adapters on to the R-12 fittings when changing over.

AHA, that explains a lot, Bob! So, in this pic what I'm looking at are the R134 adapters screwed on to the R12 fittings I bet. Can you confirm this?
http://forums.pelicanparts.com/uploa...1530313876.jpg

If so, then I bet the adapter is leaking. Are these adapters universal for all compressors?

Yes, Sir. Confirmed.

R-12 and R-134 fittings are for the most part universal. I have seen other R-12 sizes for the high side on a few old cars but rare. When I say old - not as old as ours (still pre R-134) but ours have the universal fittings.

Pressure side is the fatty. Suction (low) side is the little one.

The seal may be tired on your leaker.

Buy another update kit and get new seals?

I would ask the members here about how much R-134 to add once sorted. It's kind of a process.

Do you have a sticker saying how much R-12 to add? I think the 89 930 requires about 48 oz.

Thanks, Bob.

Yeah, I'm not exactly sure where the leak actually is. Last year I added R134 and it was leaking out of the pressure side. So once everything leaked out I replaced the schrader valve on the pressure side. I tried holding a vacuum again and it still won't hold. Essentially, if I remove the red cap I get a suction sound. So it seems like it's still leaking out of the brand new schrader valve which just doesn't seem right to me. I thought at bare minimum I'd replace the valve, but I didn't realize that there was an adapter on there. I'll start there and see what happens.

I do indeed have a sticker on my air socket that says how much R12 to add. Opinions on here are that R134 will be a lesser amount, so I should go by low/high pressure readings on the manifold gauges. I tried this previously and didn't have much luck, as the vent temps never got colder than about 60. I haven't gone through any of the system other than to replace the receiver/dryer, however. At this point I'd like to just have SOME cooling for my roadtrip to rennsport reunion in a few months.

Thanks for the input!

Matt

Cool. You have been reading.

My pals mentioned 89 930 had a blocked expansion valve with 28k miles.

It's maybe $27 and some contortion work to replace. Don't forget Prestite tape.

High side - 425psi before replacement.

425psi? Jesus. That's kind of scary.

On another note, I may have figured out my leak. I removed the r134a adapter, and that enabled me to stick the little schrader valve tool into the hole deeper and tighten it quite a bit more, like 3 turns more. I'm hoping that's the source of my leak.

That being said, I'm still going to replace the Tx valve.

Thanks, Bob!

There are high quality R12-R134 conversion valves around, which have their own internal schrader valve. You remove the R12 valve completely, thread the conversion valves on (maybe with a touch of thread sealant), then use the internal valve as the working valve. Much better than then cheap conversion valves that try to use the old schrader valves.

The ones I have laying around are steel, and weight about 4 times what the cheap aluminum ones at the store cost. I know Griffith supplies them, you might find them elsewhere.
https://griffiths.com/product/911-r134a-conversion-kit-basic-70-83-york/

These:
https://www.amazon.com/MagiDeal-Couplers-Connectors-Adapter-Retrofit/dp/B071J42WP6

Not these:
https://www.amazon.com/TOOGOO-R134A-Conversion-Adapter-Thread/dp/B073CSY212

Hey Mike - sorry for my ignorance, but when you say, "remove the R12 valve completely", do you mean you remove just the existing schrader valve? I guess I didn't pay that close attention, but it seems like the outer threaded part of the valve is not removable from the whole piece that is bolted to the compressor itself.

Yes, remove the schrader valve from the compressor assembly/head/connector thing.

But you obviously can't do that with the ones that you have, since they don't have an integrated valve themselves. If you find that you can't get your setup to seal at the connectors, you might consider the slightly more expensive but significantly better steel adapters with the integrated valves.

Gotcha. Understood. Thanks again!

Matt

To tighten the Schrader valves, I use a TPMS valve stem torque tool. It ensures the valve is tight but not too tight.

^^^ Exactly!

As a postscript, I charged the system with just over 36 oz of r134a. I managed to get approximately 30 degree temperature differentials.

One question: I actually had ice build up on the inlet line into the compressor. Normal? If so, can I wrap that inlet with the prestite tape to keep the condensation and ice from forming?

Normal.

Ice/frost is good.

You can but there are other places that some diligent grunt work will pay greater dividends.