A/C re-installed - how much oil / R134a to add and should I change the compressor?

[WHO1DMC]

I'm using the white GM orifice tube and for around 3 bucks it works great. I'm using the original hoses and had to trim off some leftover manufacturing junk so the fitting would go on and not crush the thing. But all n all not bad.




Dave B.

[DMC5180]

You could go with this one. It comes with the QV head ( horizontal ports)

https://coldhose.com/products/new-sa...-v-belt-clutch


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[82DMC12]

Thanks guys, I decided to upgrade to the 7 piston 4708 compressor while I have the system in a state of discharge right now. Wasn't looking to spend extra money now that I'm 95% done with a frame-off restoration but as they say.... "now's the time".

https://www.acparts.com/product/new-...mpressor-4708/

[DMC5180]

Even though the 4708 you chose comes with the QD style head. It is missing one thing. The High pressure safety relief valve.

https://coldhose.com/products/sanden...ompressor-head

Technically the Delorean system has the High Pressure Cut-out switch. The HP safety relief valve provides an extra level of safety.


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[82DMC12]

Even though the 4708 you chose comes with the QD style head. It is missing one thing. The High pressure safety relief valve.

https://coldhose.com/products/sanden...ompressor-head

Technically the Delorean system has the High Pressure Cut-out switch. The HP safety relief valve provides an extra level of safety.


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Hey you are right. Damn. Well my current compressor doesn't have a high pressure relief. You think I should get that QD plate with the valve too?

[DMC5180]

Well it?s up to you, I did just for the extra layer of safety. It?s a CYA thing


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[David T]

If you don't put a relief valve in don't worry, if the pressure gets too high you will just burst a hose. While the relief valve is not required it is good to have. Some systems use a burst disc.

[Ethan Rode]

The only Deloreans not equipped with a high pressure relief valve were the very early cars that haven't had the AC recall done. The HPR valve is either on a block on the condenser, or in the hub with the HP cut off switch near the receiver/dryer.

The HPR valve on the compressor head may interfere with your hoses. It messes with the clocking of the DGo hoses I've use in the past.

Be aware that many "pad style" heads have different size ports. I've seen them labeled as both QD, QC, or SJ. You'll need to slightly enlarge the ID of the smaller hole on a drill press. I can't recall the drill size at the moment.

The regular white or white/black oriface tube is the one to use. The variable oriface tube does not improve performance in my experience.

[82DMC12]

The only Deloreans not equipped with a high pressure relief valve were the very early cars that haven't had the AC recall done. The HPR valve is either on a block on the condenser, or in the hub with the HP cut off switch near the receiver/dryer.

The HPR valve on the compressor head may interfere with your hoses. It messes with the clocking of the DGo hoses I've use in the past.

Be aware that many "pad style" heads have different size ports. I've seen them labeled as both QD, QC, or SJ. You'll need to slightly enlarge the ID of the smaller hole on a drill press. I can't recall the drill size at the moment.

The regular white or white/black oriface tube is the one to use. The variable oriface tube does not improve performance in my experience.

Ohhhh damn you are right! I totally forgot I already have a high pressure relief in this wet/dry glass that came with my Hervey kit a long time ago. This picture is from before my frame-off but you can see the HPR on the side of the black thing. I should be good to go!

PXL_20220903_132158077.jpg

[82DMC12]

Well it?s up to you, I did just for the extra layer of safety. It?s a CYA thing


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I ran into a little snag while putting this back together.

To review: I now have an SD7H15 (470 compressor which I believe has a QC head without the provision for a HPR valve. My hoses fit perfectly fine and leak-free to the compressor and the included head. However, I am going to replace my Hervey mess up front and I want to have the HPR valve on the compressor if that is possible.

I ordered the QD head from coldhose.com and fit it this morning to the compressor.

On re-installation of the hoses, I found the suction hoses fits normally but the hole in the head for the discharge side is slightly smaller than the hose requires. Taking some measurements, I find the old QC head has ID of 16.41 mm on both suction and discharge sides. The QD head has suction ID of 16.41 but the discharge is about 15.4 mm. The hose are both a 15.9 mm connection! Thus the discharge hose will not connect up with the QD head.

I reached out to coldhose this morning who said they "could not locate a compatible head with the HPR provision". They said the QD head is model-specific so it probably would not work in a custom application. I am reaching out to another Sanden distributor to see if they can figure something out.

Has anyone else ran into this? I'm not going to replace the hoses over this issue because I could always get a condenser block with the HPR in it and be done with it but if there is a different head that works that would really be ideal.

And, perhaps this information helps someone else in the future.

PXL_20221107_134521577.jpg









In this picture, you see the port size of my hoses - both S and D hoses are the same size










PXL_20221107_134623991.jpg







Here is the QC head that came with the 4708 compressor - both ports are equal size and work with my hoses. The QD head has a slightly smaller discharge port (about 15mm). Not good in my situation!