The Detailed E30 R-134a Conversion Thread/DIY

[cory58]

A drier is a drier as long as the right fittings are there and the mounting brackets for that compressor are NLA

Jeff,

Since you're an E30 entrepreneur, you should start selling copies of your Sanden bracket. I would buy two.

Cory

[parkerbink]

Ok, that is the compressor currently in my car so I have the mounts for an exact replacement compressor.

Thanks

[jeffnhiscars]

A drier is a drier as long as the right fittings are there and the mounting brackets for that compressor are NLA

[parkerbink]

Last night my AC belt started screeching and ate it's self. The pulley had siezed.

I found an aftermarket compressor Sandeen SD508 in there, after researching it seems it is an R134A unit.

The seller I found my replacement (same model) from asked for pics of the Condenser, drier and expansion valve. I couldn't take the car apart at that point but he said the dryer looked different than original.

Is that evidence it was already converted or is there more I need to look for?

Here are the dryer and label on the compressor:

[cory58]

Coincidentally, I've been trying to replace that high side hose on my Touring with the updated 134a version. Local dealer here said it was on indefinite back order. I needed to order some euro parts from Schmiedmann, so I added the hose to that order, just to see what happens. I will report back when I get the shipping confirmation from Schmiedmann.Cory

Got the order from Schmiedmann, with the high side 134a hose So much for the indefinite back order! It has the correct 134a fitting. Will be interesting to see how it fits with the hood hinge. Will report back once it's installed. The part number is 64-53-8-391-040.

134a dryer pressure hose by cory58f5, on Flickr

Cory

[iitsMikE30]

I wouldn't be running the system with the 134a, just filling the system so it exerts pressure to detect leaks...maybe I'll just fill it with compressed air, and use the soapy water method to find any leaks.

Compressed air = moisture = a refrigeration system's worst enemy.

You'll do more harm then good. Use nitrogen.

[jrobie79]

I sure wouldn't do that. You need to run the system to fully charge it and obviously you wouldn't do that without oil. The compatibility issue when converting is the oil. If you have an r12 system with mineral oil you DO NOT want to mix that w 134. It's one thing to flush Pag from a new compresssor but you don't want to contaminate the whole system.

Sniffer testers I believe detect halides so id ask an expert what gas they use to test r12 systems

I wouldn't be running the system with the 134a, just filling the system so it exerts pressure to detect leaks...maybe I'll just fill it with compressed air, and use the soapy water method to find any leaks.

[jeffnhiscars]

I am planning on using r12...so I'd like to avoid filling it with r12 if there is a leak. Can I just use 134a WITHOUT oil as a means to charge the system and locate the leak, then evacuate the 134 and refill with r12?

The compressor being filled is a moot point as I'm going with r12 I'll need to flush it regardless.

I sure wouldn't do that. You need to run the system to fully charge it and obviously you wouldn't do that without oil. The compatibility issue when converting is the oil. If you have an r12 system with mineral oil you DO NOT want to mix that w 134. It's one thing to flush Pag from a new compresssor but you don't want to contaminate the whole system.

Sniffer testers I believe detect halides so id ask an expert what gas they use to test r12 systems

[jrobie79]

Im with Will on this one. If you lose a vacuum that quickly you will lose refrigerant just as fast.

Leak testing under vacuum is an issue since a) if you use a sniffer there is no refrigerant to sniff and b) if you use a spray liquid it will get sucked in rather than bubbling since there is no pressure in the system. You have a couple of options. I buy r134 cheap enough that I'd throw in a can or just charge the system and test from there. I prefer a sniffer but use that and a "leak detector since leaks can be pesky to find. I suspect yours will be easy given the volume.

Some use nitrogen or even propane but I suspect thats more for r12 where the $$ is so high. Regardless of how you go about testing keep in mind that its very easy to over tighten orings so they dont seal. r12 hoses can also hold r134 for a while since they are impregnated with mineral oil (even after a proper fluch) but in time that can change as the mineral oil leeches out and the hoses will leak along their length, so dont just test fittings. I went 3 years topping up 2-3x/season until I realized the 2 hoses behind the glove box were leaking like sieves along their length. They were the only 2 I didnt replace intially so I sent them out for upgrading and all is well (so far).

I am planning on using r12...so I'd like to avoid filling it with r12 if there is a leak. Can I just use 134a WITHOUT oil as a means to charge the system and locate the leak, then evacuate the 134 and refill with r12?

The compressor being filled is a moot point as I'm going with r12 I'll need to flush it regardless.

[cory58]

I thought the EPA mandated, in typically short sighted fashion, that the adapters were not to be removable...

Both my E30s have removable adapters. You can also buy 134a conversion kits at all the major auto parts stores that contain screw-on adapters.


Maybe the govt didn't totally screw something up this time? Not likely!


Cory

[jeffnhiscars]

quick question....how long should the system hold vacuum? I was working in my garage, I hooked up the vacuum pump, it was holding steady at -30 the entire time. I shut the valve on the guage set, and it continued to hold -30. I went away for the weekend with everything still connected and when I came back yesterday, the system was no longer under vacuum. SHould this be ok to charge? How would I find a leak this small? It's a completely evacuated system, I R&R'd the whole thing with new o-rings and Nylog sealant....how would I go about finding a leak?

Also do compressors come pre-oiled? I bought a brand new one on ebay for my m42, just wanted to know if it comes with oil or not?

Im with Will on this one. If you lose a vacuum that quickly you will lose refrigerant just as fast.

Leak testing under vacuum is an issue since a) if you use a sniffer there is no refrigerant to sniff and b) if you use a spray liquid it will get sucked in rather than bubbling since there is no pressure in the system. You have a couple of options. I buy r134 cheap enough that I'd throw in a can or just charge the system and test from there. I prefer a sniffer but use that and a "leak detector since leaks can be pesky to find. I suspect yours will be easy given the volume.

Some use nitrogen or even propane but I suspect thats more for r12 where the $$ is so high. Regardless of how you go about testing keep in mind that its very easy to over tighten orings so they dont seal. r12 hoses can also hold r134 for a while since they are impregnated with mineral oil (even after a proper fluch) but in time that can change as the mineral oil leeches out and the hoses will leak along their length, so dont just test fittings. I went 3 years topping up 2-3x/season until I realized the 2 hoses behind the glove box were leaking like sieves along their length. They were the only 2 I didnt replace intially so I sent them out for upgrading and all is well (so far).

IME new compressors should have oil and my Seltec actually had a label telling me how much. I think 150cc is typically but YEMV. IIRC correctly total capacity is 240cc and you should add the difference throughout in different component if you are doing a complete overhaul. If swapping individual components add as well (ie 10cc per hose or drier). There are also different weights of PAG so find out which your compressor has.

[jrobie79]

The system shouldn't leak down over a weekend. You'll need a leak sniffer, or soap and a lot of patience.

Ask the vendor if it has oil inside or not.

It's a denso, brand new. I asked the seller, but he had no idea. I did notice a little "oil" when I change the top manifold plate to the e30 one. I'll flush and refill regardless

[The Dark Side of Will]

The system shouldn't leak down over a weekend. You'll need a leak sniffer, or soap and a lot of patience.

Ask the vendor if it has oil inside or not.

[jrobie79]

quick question....how long should the system hold vacuum? I was working in my garage, I hooked up the vacuum pump, it was holding steady at -30 the entire time. I shut the valve on the guage set, and it continued to hold -30. I went away for the weekend with everything still connected and when I came back yesterday, the system was no longer under vacuum. SHould this be ok to charge? How would I find a leak this small? It's a completely evacuated system, I R&R'd the whole thing with new o-rings and Nylog sealant....how would I go about finding a leak?

Also do compressors come pre-oiled? I bought a brand new one on ebay for my m42, just wanted to know if it comes with oil or not?

[The Dark Side of Will]

When I picked up the car, the hood would not close, because the High Side R134a Adapter was too tall. The technician took the adapter off so I could close the hood.

I thought the EPA mandated, in typically short sighted fashion, that the adapters were not to be removable...