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I'm converting my A/C to R134 and wonder whether 1979 528i A/C hoses are "barrier" hoses ? My A/C components look very good with no oil on any of the connections. I'm thinking of just recovering the R12 and replacing it with R134 and see if it works and for how long.

(p.s. I did read the "AC Repair FAQ" on this forum)

None of the hoses are really barrier hoses, but if you have the red, cloth covered ones it's emphatically no. The black rubber ones are better, but still not barrier. I would change the high side hoses if they're red, but the low side is probably ok.

ty Mike

Mike W. wrote:None of the hoses are really barrier hoses, but if you have the red, cloth covered ones it's emphatically no. The black rubber ones are better, but still not barrier. I would change the high side hoses if they're red, but the low side is probably ok.

I have my motor out of the car and will be freshening everything up when I put it back in.

I know that my AC hoses were leaking in the past, as a charge lasted about two weeks.

I was planning to redo the hoses per the FAQ write up, but then was told that the r134 conversion needs to use different hose end connections (with O-rings). What do you guys make of that?

I did have my condenser tested and it checked out good.

Don't even bother with the conversion. Just rent a vacuum pump and a set a manifold gauges, and charge the system with freeze 12. You really don't even need to measure how much you put in, just with the freeze 12 fill the system until you see a steady stream of bubbles in the sight glass. You're supposed to use a slightly lower charge with it than with r12, so it's probably right around 2 pounds. Granted, you wouldn't be able to have a shop work on the system once the freeze 12 gets in it, but who cares. It saves having to pull the compressor, change the oil, and change all of your o rings, not to mention the drier.
If you have a small leak somewhere, fix it at the spot, or just keep a few extra cans of freeze 12 around and charge it as necessary. It's a much cheaper route that doing the conversion, and actually allows the system to be nearly as efficient as with actual r12. The major limiting factors on these cars are the size of the condenser and evaporator, which is exacerbated by the use of r134.
Just my 2 cents.

Blaise wrote:I have my motor out of the car and will be freshening everything up when I put it back in.

I know that my AC hoses were leaking in the past, as a charge lasted about two weeks.

I was planning to redo the hoses per the FAQ write up, but then was told that the r134 conversion needs to use different hose end connections (with O-rings). What do you guys make of that?

I did have my condenser tested and it checked out good.

No, you will need new connections to charge it, adapters really that screw on, but the copper gasket at the hose end doesn't care if it's 12 or 134a. BTW, R12 is down in price from it's peak and often available for a moderate price on Craigslist. Not that it would be technically legal to do so, but people do.

I'll second freeze 12. Discovered it when I first got the e12, been using it ever since. Hard to find in Cali, so I had to order cases from the distributor, but has been worth it.

r12 is also plentiful on Ebay, $12-30/can.

My flex hoses have typical brass flared gas connections at then ends, plus copper crush washers. Are those crush washers standard flat, or special shapes?

I see it listed on realoem as 64531350491 and noted as conical ring.

The washers are conical-shaped to conform to the flared connections.

socalfiver wrote:The washers are conical-shaped to conform to the flared connections.

They come that way? I am asking, because I figured that a flat copper washer would easily conform.

They come that way.

You don't want a flat washer being forced into a shape for which it's not designed. Only after you've torqued the thing down can you know if it split, isn't sealing completely, and then you have to take it apart to find out!!

Last time I needed to reassemble the system, after having replaced the high pressure hose, and another copper line, I found quite an assortment in a catalog from O'Reilly's Auto Parts, the national chain. Had them order a few sizes and bought the ones that were the closest match. One was dead on.

Great, thank you

What seems to be the going rate to rebuild the three flex hoses?

I lucked out and bought a rebuilt set for $10 on ebay. I'm guessing around $70-100 to do all 3 hoses.

You can do it yourself. There's directions in the a/c FAQ.