R12 to R134 AC Conversion Part Selection

[dcwang3]

I have read so many threads about converting the AC system to R134. There are tons of info and need some clarifications on some items. I have a 92 325i convertible (ec28828). I am planning on keeping the stock fan for PnP operation but upgrading the condenser to a parallel flow.

based on what I read, here are the things that I should be replacing.

• Compressor : 64528385712
• Condenser: 64538391509
• Receiver Drier: 64538391025
• Expansion Valve: 64518391209
• All Oring Kit: 6450839060

Can all of the barrier hoses and pipes that have the H/L valves be reused by flushing them out? Can a valve retrofit kit be used to adapt the R12 to R134 valves? Any issues with clearances with the adapters?

How about pressure switches, can the current ones be used?

Any insights would be great!

[superj]

All i have ever done is the valve kit and the ac worked fine.

I have also used a different refrigerant than 134 now and it works great, r290. Its available everywhere and is cheap. It also works great in r12 systems because its molecules are the same size so no leaks. R290 ia commonly known as propane

[Jeffnhiscars]

Pressure switches are fine and I believe a 92 would have barrier hoses which should be fine to reuse after a good flush. Try to read the markings on the hose to confirm, otherwise they will leak. Def change the expansion valve and unless you're replacing the compressor with one designed specifically for r134 your existing compressor should have r134 compatible seals.

[H.J. 1981]

The correct retrofit valves from BMW are:

64 11 8 363 260

64 11 8 363 259

They come without a schrader valve and mount on top of existing R12 valves, and most importantly they are "short" and clear the hood just fine.

Alternatively, you can get the low pressure side from any online seller, but the high pressure side valve needs to be very short indeed. I tested 8+ ones various sizes from ebay, none cleared the hood strut expect the more expensive OE BMW one.

I checked that condensor, locally in Germany it is still a tube and fine design. Nissens offers a direct parallel flow alternative for the E30 94172 model number.

I removed every hose in the engine bay and flushed them out, some minor rust were at the connection ends but nothing serious. I kept the stock fan, but i believe it is a bit weak with the R134a system and new condenser, since in traffic it is cooling okay (not great) but once moving the cooling is amazing (however i do suspect a tiny leak somewhere, will check in Spring).

I followed the R134a conversion thread of the r3vlimited forums, very detailed there and there is a compressor list if you wish to be certain if you need a new compressor or to flush out the one you have and get the correct oil. I replaced the expansion valve, drier/receiver and pressure switch (my car is a 1990 model, and it already came with the updated single switch from the factory, i did not need to re-wire anything).

[superj]

if you reuse your compressor, unbolt the part where the hose connects and clean out the inside of that area. on my son's 86, we took the connections off the compressor and there was a lot of little tiny rock looking pieces in it. I don't know what they were or where they came from but we cleaned it out completely and added new oil. his car blows in the high 40s at the vent during summer here in south texas. we used propane instead of Freon though so if you use 134, your numbers will be higher at the vent

[dcwang3]

Pressure switches are fine and I believe a 92 would have barrier hoses which should be fine to reuse after a good flush. Try to read the markings on the hose to confirm, otherwise they will leak. Def change the expansion valve and unless you're replacing the compressor with one designed specifically for r134 your existing compressor should have r134 compatible seals.

Yes, mine has the barrier hoses.

FYI the compressor that is has is the Seiko Seiko SS-148PB3. I was looking around for a replacement with PN 64528385712 and there are several different options/brands. I looked at pelican parts (as an example) and there are four different ones. (https://www.pelicanparts.com/catalog/SuperCat/0205/BMW_0205_VENTAC_pg1.htm#item5). They say specifically it fits for only cars that came with a certain brand either Behr, Bosch, or Denso. Just by looking at the pictures and comparing it with what I currently have, the genuine BMW one is exact. The next closest is the Four Seasons with the small little flange. The other two do not look like they would fit.

Would it be stupid to assume that either those first two that look very similar will fit or should I just buy the one that looks EXACTLY like what I have?

Also, is that Seiko Seiki model that I have R134 compatible? It is labeled R12 specifically, the number is 64521386464….

The correct retrofit valves from BMW are:

64 11 8 363 260

64 11 8 363 259

They come without a schrader valve and mount on top of existing R12 valves, and most importantly they are "short" and clear the hood just fine.

Alternatively, you can get the low pressure side from any online seller, but the high pressure side valve needs to be very short indeed. I tested 8+ ones various sizes from ebay, none cleared the hood strut expect the more expensive OE BMW one.

I checked that condensor, locally in Germany it is still a tube and fine design. Nissens offers a direct parallel flow alternative for the E30 94172 model number.

I removed every hose in the engine bay and flushed them out, some minor rust were at the connection ends but nothing serious. I kept the stock fan, but i believe it is a bit weak with the R134a system and new condenser, since in traffic it is cooling okay (not great) but once moving the cooling is amazing (however i do suspect a tiny leak somewhere, will check in Spring).

I followed the R134a conversion thread of the r3vlimited forums, very detailed there and there is a compressor list if you wish to be certain if you need a new compressor or to flush out the one you have and get the correct oil. I replaced the expansion valve, drier/receiver and pressure switch (my car is a 1990 model, and it already came with the updated single switch from the factory, i did not need to re-wire anything).

Is the low side right by the fender well while the high side is wrapped around the passenger strut tower?

Maybe this is a stupid question but if you put a valve that doesn't have a Schrader valve, will a standard R134 AC fill fitting be long enough to depress the pin?

Thanks for the Nissin alternative part number. It wasn't quite clear and couldn't find more information on it. I have also heard that amazon has an ADPI (https://www.amazon.com/APDI-7013464-.../dp/B007ZOESL6) that is also a parallel flow.

If the stock fan is slightly weak, how hard is it to hook up an electric pusher fan? I saw in Jeffnhiscars has a good writeup for his zinno vert but I couldn't find the SPAL harness that he used. Jeff - do they still make it or know of an alternative?

[Jeffnhiscars]

They are r12 specific in terms of how they are engineered but most OE and virtually all replacement compressors today will have r134 compatible seals...but they are still r12 compressors. The difference is if it fits your bracket (I believe they all will) and if your hoses attach. If yours still works there is no advantage in replacing it with an OE version

Buying an OE replacement gives you a fresh r12 compressor with the same design limitations when used with r134 and IME those are all far more expensive than a brand new r134 specific model. The problem then becomes mounting it since the brackets are NLA.

Choose your poison.

[dcwang3]

the replacement compressors under PN 64528385712 are suppose to be r134 and two of them look like they will fit the bracket that i currently have.

any other gotchas or lessons learned that I should be aware about?

[H.J. 1981]

Yes, mine has the barrier hoses.

FYI the compressor that is has is the Seiko Seiko SS-148PB3. I was looking around for a replacement with PN 64528385712 and there are several different options/brands. I looked at pelican parts (as an example) and there are four different ones. (https://www.pelicanparts.com/catalog/SuperCat/0205/BMW_0205_VENTAC_pg1.htm#item5). They say specifically it fits for only cars that came with a certain brand either Behr, Bosch, or Denso. Just by looking at the pictures and comparing it with what I currently have, the genuine BMW one is exact. The next closest is the Four Seasons with the small little flange. The other two do not look like they would fit.

Would it be stupid to assume that either those first two that look very similar will fit or should I just buy the one that looks EXACTLY like what I have?

Also, is that Seiko Seiki model that I have R134 compatible? It is labeled R12 specifically, the number is 64521386464….




Is the low side right by the fender well while the high side is wrapped around the passenger strut tower?

Maybe this is a stupid question but if you put a valve that doesn't have a Schrader valve, will a standard R134 AC fill fitting be long enough to depress the pin?

Thanks for the Nissin alternative part number. It wasn't quite clear and couldn't find more information on it. I have also heard that amazon has an ADPI (https://www.amazon.com/APDI-7013464-.../dp/B007ZOESL6) that is also a parallel flow.

If the stock fan is slightly weak, how hard is it to hook up an electric pusher fan? I saw in Jeffnhiscars has a good writeup for his zinno vert but I couldn't find the SPAL harness that he used. Jeff - do they still make it or know of an alternative?

The low side is what runs near the strut tower, the high side is squashed up in the fender. I can not comment on that ADPI condenser, only giving you what i found and actually used. The stock fan is designed for the tube and fin style system, so realistically any fan would work. Since the R134a system runs significantly hotter, a better heatsink (aka condenser) is required and technically a fan as well. I read somewhere that SPAL makes near bolt on applications on their 14" fans that run 2,400+CFM and i know at least one person who used a stock E34 fan with some slight tweaks to mount it up, but both cases used the stock harness and resistor to trigger both fan speeds. Nissens actually makes direct fan replacements for almost all BMWs, the 7 series included. So either pick up a used or new fan and just focus on the mounting points and hook it up you should be fine. A new 7 series fan costs €100 from Nissens (almost €300 from dealership), SPAL fan runs in the mid €60s and can be a tad louder from the outside.

Personally, when spring comes, i shall chase the whole system for leaks and probably replace the fan with a SPAL one, they are known to be really good and reliable in the motorsports industry here.

- - - Updated - - -

They are r12 specific in terms of how they are engineered but most OE and virtually all replacement compressors today will have r134 compatible seals...but they are still r12 compressors. The difference is if it fits your bracket (I believe they all will) and if your hoses attach. If yours still works there is no advantage in replacing it with an OE version

Buying an OE replacement gives you a fresh r12 compressor with the same design limitations when used with r134 and IME those are all far more expensive than a brand new r134 specific model. The problem then becomes mounting it since the brackets are NLA.

Choose your poison.

That is new to me, i asked the dealership and first it is NLA from BMW. Second they found the R134a conversion kit, which included those adapters for low/high side, a new receiver/dryer and a sticker. Not even the condenser, compressor oil, seals etc were part of that kit.

[dcwang3]

Is it possible to run the fan at one higher speed? Is there any benefits to running different fan speeds?

Also, is a 14" pusher the largest than can be mounted? curved or straight blade? What is the max depth the fan can be?

[superj]

the older e30s had straight blades but I think the plastic bumper cars had a newer style curved blade fan. they run at different speeds, high and low, if I remember right.

I used my ac fan as a cooling fan on my 89. I took the mechanical fan off and removed the ac stuff and the car stayed cool during south texas 100+ degree summers so I think the fan is not the trouble

[dcwang3]

I started taking all the hard lines, compressor, condenser, fan, etc… from the engine bay. I did order the retrofit valves that HJ recommended above and planning on using the existing lines (will flush them out):

64 11 8 363 260
64 11 8 363 259

The low side one fits fine. The high side which runs along the fender has issues. There is clearance issues with the hood hinge. Even as it is, there is a very small gap clearance.

Question is…when is the high side port used? Is it used during filling? Can I just leave the retrofit valve off and then when I need to use it, put it on?

Or if I order the hard line, will it come with the correct fitting?

[aaverhulst]

After you spent all that money and time on doing a complete conversion, I can't image not going ahead and finishing it right. I have only used the high side to monitor the high pressure side. I've never had a problem on the high side. When I did mine, I got a $30 kit from O'Rilley that included valve conversions, R134 and oil. Never had a problem except having to add R134 every year..

[H.J. 1981]

I started taking all the hard lines, compressor, condenser, fan, etc… from the engine bay. I did order the retrofit valves that HJ recommended above and planning on using the existing lines (will flush them out):

64 11 8 363 260
64 11 8 363 259

The low side one fits fine. The high side which runs along the fender has issues. There is clearance issues with the hood hinge. Even as it is, there is a very small gap clearance.

Question is…when is the high side port used? Is it used during filling? Can I just leave the retrofit valve off and then when I need to use it, put it on?

Or if I order the hard line, will it come with the correct fitting?

You can slightly adjust the hood hinge by loosening the 13mm nut and sliding the hinge on the stud to gain some small clearance.

Unsure what you have available in the USA, in Germany when i was about to order a new hardline, it was NLA and another model was available for the convertible models. Picture showed a very long protruding extension for the valve which would surely not fit. Check locally!

[Thrifty S50]

I just paid a shop $275 to get er done. Tech told me it was simple, just draining the Compressor, changing the valves and seals, then refilling with R134 about 80% full, something about the pressure that the R12 vs R134 work at. Lots of people complain its not cold enough but Im in Los Angeles and its perfect for the weather down here.

[dcwang3]

You can slightly adjust the hood hinge by loosening the 13mm nut and sliding the hinge on the stud to gain some small clearance.

Unsure what you have available in the USA, in Germany when i was about to order a new hardline, it was NLA and another model was available for the convertible models. Picture showed a very long protruding extension for the valve which would surely not fit. Check locally!

ok so from looking at realoem.

The pressure line that is original to the car is 64531381740. The valve sits right near where the hood hinge bolts too.
https://www.ecstuning.com/b-genuine-...e/64531381740/

Here is the replacement for R134 and for convertibles. Looks like it removes it much further towards the front probably underneath the washer fluid tank, thus it being protruded out. Looks like I'll need to get this line if I want to do it the correct way then then use the adapter on the low side….
https://www.ecstuning.com/b-genuine-...e/64538391040/

I just paid a shop $275 to get er done. Tech told me it was simple, just draining the Compressor, changing the valves and seals, then refilling with R134 about 80% full, something about the pressure that the R12 vs R134 work at. Lots of people complain its not cold enough but Im in Los Angeles and its perfect for the weather down here.

I live in central Florida, what kills is the humidity.

[goinstrong]

This is what I did with our '88 325iC. Evidently, the molecule is larger, so the O rings don't have to be changed out. I recharged it a couple years ago, and it still blows ICE cold. It comes with a "how to" CD. It was very simple and took about 10 minutes.

https://www.ebay.com/itm/R12-COMPATI...4AAOxyqUpQ8fty

[dcwang3]

So update. I finally pulled vacuum and recharged the system. I put ~6 oz of PAG46. 3oz was precharged in the remanufactured compressor (most likely a BOSCH), then I distributed the rest as below based on a DENSO write up:

Compressor: 50%
Evaporator: 20%
Condensor: 10%
Dryer: 10%
Hoses: 10%

Here are my results:

Ambient Temp: 72 deg F
Humidity: ~90%

1st 12oz can:
Low 33psi, High 165psi
Vent Temp 48.8 deg F
Fan speed 1

This first 12oz of R134 surprised me because it was very close to what the nominal temps BMW recommended (90% Humidity, outside air 70 deg F, Vent Temp 46, Low 33, High 183). I knew that 12 oz was not even enough so decided to throw another 12oz can.

2nd 12oz can:
Low - 30psi, High - 225psi
Vent Temp 44.8 deg F

I decided to cycle the compressor a few times then rechecked the pressures.

Low - 34psi, High 225 to 235psi
Vent Temp 46.5 deg F


What do you guys think? I don't think it's too bad, but could be better. Since I only put about 24oz, you think some more can be added?

Also, one thing that I noticed, is it typically that if you put the fan speed to 4 that the vent temps are higher? I was getting around 63.5 deg F when at speed 4, and it seems like it changed my pressure readings to Low 46psi, High 250psi. I looked at the dryer sight glass it there is some bubbling.

This is my first time doing this so trying to understand whether this seems reasonably.

[superj]

we always checked our temps with the fan on high so I think you might be low on Freon a little. I am not 100% sure though because I have very little ac experience.

but I would think for those ambient outside temps, you would be cooler

[dcwang3]

so I drove around crusing about 20-30mph, the temp will get down in the 40's. When looking at youtube videos on filling, it seems like a lot of people are checking the temps based on the lowest setting.

It makes sense that since the compressor is not running very fast at idle, blowing fast ambient air across the evaporator will make the temps out the vents much higher. As of right now, I am using the stock harness with the resistors, so if I bypass the resistor so that the fan is on high, then maybe I will get colder temps?

Another thing is that since I got a remanufactured compressor, it's mostly an R12 compressor fitted for R134A, so it's probably not very efficient at all.

Sometimes it's very loud when I first start up the car, but quiets down after revving it for like 10 seconds or just starting to drive it around.

[superj]

ours was the original 87 system and we got into the 40s idling on high. and that was in july or august here in south texas so high temps and higher humidity.

I would think you should be able to get better then our readings

[Jeffnhiscars]

By passing the resistor will give you better cooling at idle but when underway the fan contributes less than your MPH. If you're getting a temp differential in the mid to upper 20s you're doing fine especially with humidity at 90% since all that condensing vapor sheds heat in your evaporator....which is inside your car

[dcwang3]

ours was the original 87 system and we got into the 40s idling on high. and that was in july or august here in south texas so high temps and higher humidity.

I would think you should be able to get better then our readings

SuperJ - You mentioned you used r290? I wonder if that is one of the factors why you have such a large temp differential. Do you have any issues with getting it serviced by a shop?

By passing the resistor will give you better cooling at idle but when underway the fan contributes less than your MPH. If you're getting a temp differential in the mid to upper 20s you're doing fine especially with humidity at 90% since all that condensing vapor sheds heat in your evaporator....which is inside your car

Jeff - I think I'm going to test out bypassing the resistor and compare at idle. But what compressor did you use, was it designed specifically for R134 versus what I have is a remanufactured BOSCH that I assume was designed for R12 but fitted for R134 compatibility...

[superj]

I don't know about any shops, i bought a vacuum pump and googled how to do everything