AC compressor rebuild/replacement

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sowhatsg
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AC compressor rebuild/replacement

Post by sowhatsg »

Hello,
My 628CSi AC runs on a Denso compressor which out of service and needs rebuild or replacement. Can I replace it with any compressor suitable for an E24?
The thing is now with an aircon (not cars) specialist who has been trying to find seals and other parts to rebuild it with no avail. He has found a rebuilt that was on a 635 and another on a 633. Would that work on the 628?
The old compressor and detail of the label can be found here with other pictures of the car. It was running on R12 and a conversion is needed.
https://photos.app.goo.gl/iKqMdi3L6EJ3dnJV9
Any advice would be appreciated.

For info, it's a Euro spec E24 1983 628CSi.

Thanks

Christian
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86_6series
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Re: AC compressor rebuild/replacement

Post by 86_6series »

Here is a link to Jay's site. I know he's across the pond but
he the best in the states and may be a source for you.

viewtopic.php?t=28245
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bpoliakoff
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Re: AC compressor rebuild/replacement

Post by bpoliakoff »

IIRC. Jay will also sell the parts for a rebuild,...I think
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635sharknose
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Re: AC compressor rebuild/replacement

Post by 635sharknose »

If you are interested in doing it yourself, or a lot of it, then buy this book.
It has a lot of info about BMW systems and the E24 as well.
https://www.amazon.fr/Just-Needs-Rechar ... 0998950718
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Jlc
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Re: AC compressor rebuild/replacement

Post by Jlc »

Let me second Rob Siegel's book(s). You cn find all of them on his website: https://robsiegel.com

He'll sign it if you buy from him as well. All are great reads.
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sowhatsg
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Re: AC compressor rebuild/replacement

Post by sowhatsg »

Thanks for the info, it helps to know there's a good book on AC! I had been in touch with Jay a little while ago, but as pointed out, it's not very practical to be on this side of the pond, especially when we're not sure if the thing is seized or not (no oil). In this case, it's not possible to rebuild it as confirmed by Jay.
Now, the idea is to find a replacement compressor, but we're not sure if any E24 compatible would do, e.g. a Bosch one hacked from another E24 to replace the dead NipponDenso.
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Re: AC compressor rebuild/replacement

Post by Jlc »

Rob Siegel is a legend in the BMWCCA. He has been writing the"Hack Mechanic" for decades; I find his writing and outlook very enjoyable. You can see his work at Bimmerlife.com He has some good past ones on his Shark(s).

He's also on Hagerty's, here's one on A/C: https://www.hagerty.com/media/opinion/f ... e-testing/
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sowhatsg
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Re: AC compressor rebuild/replacement

Post by sowhatsg »

Research indicates the Airstal 10-1510 can replace the NipponDenso that was mounted on my car. This is confirmed by the manufacturer (airstal.com) but some resellers tell me it’s not compatible based on the VIN. The Airstal site shows the same reference as on the Denso label, so I am confused. I am ordering Rob’s book and continue to check around to found out if the thing is compatible or not.
tmoretta
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Re: AC compressor rebuild/replacement

Post by tmoretta »

I just replaced the A/C compressor and receiver/dryer in my '88 M6. Is an A/C service manifold mostly a diagnostic tool, or do I need it, in addition to a vacuum pump, to vacuum and re-fill my system? Also, how much R134a is needed to refill my system including the rear A/C?
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Ralph in Socal
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Re: AC compressor rebuild/replacement

Post by Ralph in Socal »

You don't need the gauge set but you need the vacuum pump. System evacuation is critical to removing moisture. You want to evacuate for at least 30 minutes to make sure all moisture is removed.

The gauge set makes it easy the swap from evac pump to system filling. Also allows for watching effectiveness of the system. IE - evacuate the system for 5 minutes then turn off the vacuum pump. Watch system pressure (negative pressure due to vacuum) and determine if the vacuum holds. If not the system is leaking and needs attention prior to charging refrigerant.

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tmoretta
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Re: AC compressor rebuild/replacement

Post by tmoretta »

Hey thanks. I have changed all of the original o-rings to "green" except for under the dash. I think I will only purchase a decent vacuum pump and see how it goes. I am expecting I will need 5 to 6 cans of 134a.
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Ralph in Socal
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Re: AC compressor rebuild/replacement

Post by Ralph in Socal »

Sorry I missed that part. Charge R134 at 85% of the R12 amount.

Ralph
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tmoretta
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Re: AC compressor rebuild/replacement

Post by tmoretta »

Well, what is the R12 amount?
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Ralph in Socal
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Re: AC compressor rebuild/replacement

Post by Ralph in Socal »

Look for a sticker denoting AC R12 charge. Usually pass side by the strut tower

I've never had rear AC and that adds to the charge amount.

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
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86 535i Auto (For Sale)
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tmoretta
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Re: AC compressor rebuild/replacement

Post by tmoretta »

Great thanks.
sowhatsg
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Re: AC compressor rebuild/replacement

Post by sowhatsg »

Rebuilt Bosch compressor from Airstal installed and circuit checked, dryer replaced, new belt and all working fine! Job done by a local air con specialist. He also rebuilt one of the hoses that was in bad shape.
Now, new problem appeared. Aux fan runs even when contact OFF. I have to keep battery disconnected. When fuse #3 removed, it does do it. Still does it with fuse#18 removed. Took relay K6 to replace relay K1, still does it. Did not do it when compressor was dead and R12 circuit empty.
As if high pressure cutout switch is always ON. Does that make sense? Any other possibility?

Also found out blower speed is working only on max. 1st step is to replace transistor under the hood next to windshield as it is fairly easy to reach. Looks rusty. Any advice on how to cleanly desolder the transistor from its support?

Thanks
Jlc
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Re: AC compressor rebuild/replacement

Post by Jlc »

sowhatsg wrote: Thu Apr 07, 2022 12:08 pm Also found out blower speed is working only on max. 1st step is to replace transistor under the hood next to windshield as it is fairly easy to reach. Looks rusty. Any advice on how to cleanly desolder the transistor from its support?

Thanks
There's a how too on the replacement. When I did mine (A/C), I simply used a soldering iron and drilled out the pop rivets holding teh transistor. Too reassemble, I sued a lot of thermal paste and pop riveted the new transistor in place. Pretty straightforward.
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sowhatsg
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Re: AC compressor rebuild/replacement

Post by sowhatsg »

Thanks, it worked great!
Still investigating the aux/condenser fan running with contact off. Stops running when C106 (between high-pressure cutout switch and clutch) is disconnected. When C105 and C106 are disconnected, there's voltage on C105 and C106 on the wires coming from relay and high pressure switch??
AuxFan.pdf
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