E28 Evaporator core vs. E12

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528i-1981
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E28 Evaporator core vs. E12

Post by 528i-1981 »

I'm trying to figure out if these are dimensionally the same. They have different part numbers (64 511 3 68 119 / E28 and 64 511 3 62 126 / E12) but use the same expansion valve (64 511 3 54 379).

The E28 core has o-ring fittings and the E12 unit has flare. Does anyone know if this is the only difference? I've read that the E28 evaporator was bigger than the E12s, but other places suggest they used the same Behr box with minor differences (e.g., the fittings).

Another source suggested that the E28-based E24's evaporator could be used in other applications with "some modifications." It's unclear whether that means replacing the entire evaporator assembly, or changing the flare fittings on the hard lines, so I'm still left wondering about the evaporator core's size.

Hopefully I don't need this information. I still have a slow leak somewhere and suspect the compressor, but I'm looking down the road ...

** update - a little refrigerant mixed in with nitrogen at 100 psi got the sniffer excited at the compressor pulley.
(oo=00=oo) Eric
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Robert Bondi
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Re: E28 Evaporator core vs. E12

Post by Robert Bondi »

That's a great question. I half-researched this not long ago, largely motivated by the much greater availability I was seeing
for the E28 evaporator. Hopefully, one of our resident experts, like Mike W, that have both chassis can shed some light here.
That interchange knowledge is really quite invaluable. IMO, the o-ring design is much cleaner and helps get away from needing special tools and metal ferrules that sometimes comes up with flare fittings.
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Re: E28 Evaporator core vs. E12

Post by Mike W. »

I don't know about the evaporator itself, but I'm pretty sure the A/C box including the evaporator fits. I'll see if I still have an example of both, I don't think I have an E12 box anymore but I do have an E28.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
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Re: E28 Evaporator core vs. E12

Post by 528i-1981 »

The only downside is having to change the fittings on the hard lines, which probably means replacing them outright. Not the end of the world and worth doing if the E28 evap core is your only option.
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Re: E28 Evaporator core vs. E12

Post by tlake »

528i-1981 wrote: Wed Feb 09, 2022 2:21 pm The only downside is having to change the fittings on the hard lines, which probably means replacing them outright. Not the end of the world and worth doing if the E28 evap core is your only option.
In terms of the evap core all e12s used the same unit from 1974 to 1981. The only change in the car was the cosmetic console dress panels, because BMW integrated the HVAC controls for mid 1977 model year, and such later e12s had the center part of the dash come a little forward. However, the evap core and the blower assembly/box the core sat in was the same for 1974-81.

Having had both e12 and e28, I can attest that the e28's console with the evap core / blower is a little bulkier, it catches your leg when changing gear. Whether the core is larger I don't know, but e12s and e28s have the same sized interior, and the South African e12/8s had the e28 interior, so I would think all the cars are pretty close, fittings aside.

I did notice from the parts listings that the e3, e9 and e21 seem to have the same evap core, it says all three cars used that part. :?
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Re: E28 Evaporator core vs. E12

Post by Mike W. »

OK, I got out there to measure it today. I no longer have an E12 evap box on the shelf so all I can do is give the E28 numbers.

Box. 10 3/8 wide at the top. 9 1/2 wide at the blower cages.

As to the evaporator itself, 8" wide, the finned portion, not the tubes, about 7.5 high, difficult to measure without taking it apart, which I didn't want to do, ~3" deep, again a difficult measurement without disassembly.

E12s may have all used the same evaporator, but the rest of the parts weren't the same. Mid 77 on they got a different, likely larger blower. The condenser changed at least once, maybe more, 528i's got a different, more advanced, but not parallel tube condenser. 528i's got a different, much larger aux fan up front, and 2 speed, the lower of which was likely as much if not more effective than the single speed of the early one, and high speed really moves some air, though as much or more for aux engine cooling as more A/C.

So there's much more than just the evaporator to the equation, even the later condenser in 528s was probably inadequate even as it was better than before. An illustration, due to a replacement radiator I had a rub out on the fan switch in the radiator one time, on the highway, Utah desert in summer and blew the fan fuse. Even on the freeway, A/C performance was reduced and the evaporator froze up. I was just the tinyist bit low on charge, but the aux fan not working really complicated things. With a better condenser I doubt it would have been as much, if any, of a problem.

You can't blow cold air if you don't get rid of the heat. The Europeans in general I think fixated on refrigeration theory and needing to condense the refrigerant to liquid so it could evaporate off and make cold. Which they did. But IMO they underestimated just how much heat they had to remove from the system so the condenser portion was undersized. They just didn't understand 110+F in the desert, let alone in a 15 year old car, let alone in a 40 year old car.

BTW, I would be happy to sell my E28 evap box, and I think it does perform better, but I also think the biggest problem is the condenser, especially, repeat, especially if you're not running R12. The other refrigerants need a substantial condenser upgrade just to get back to OE capability, let alone 80s-90s standards. For whatever reason the evaporator doesn't seem to be the limiting factor with different refrigerants, it's the condenser.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter
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528i-1981
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Re: E28 Evaporator core vs. E12

Post by 528i-1981 »

This is great info, thanks Mike. I'm pretty sure (knock on wood) that my evaporator is OK, since I found the leak at the compressor pulley. I had already removed the evaporator to replace the expansion valve and the thought of another dash teardown was ... discouraging to say the least.

Interesting point about the evaporator not being the limiting factor for cooling performance. I'm not sure how this figures in, but I read that there used to be different expansion valves for R134a and R12 when the changeover started, but eventually only one valve was made for both refrigerants. Maybe there was a theoretical difference in terms of theoretical cooling based on the different evaporation temps of the refrigerants, but in the real world it didn't add up to much in terms of performance. The two are actually pretty similar at the lower end of the pressure/temp range. The difference becomes more apparent above 100F. Or it was just a compromise as R12 use sunsetted and keeping two SKUs wasn't economical?

By the way, anyone that does AC work needs to have a sniffer and a nitrogen bottle - just a little R12 in the system pressurized to 100 psi with nitrogen was detectable by the sniffer - and this was a slow leak. No leaks detected in the cabin, but that's not to say there couldn't be a leak deep inside the evaporator. Once the compressor is back on, if there's still a leak, I'll consider the E28 evap as a potential workaround.
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Re: E28 Evaporator core vs. E12

Post by tlake »

Mike W. wrote: Sun Feb 13, 2022 8:14 pm OK, I got out there to measure it today. I no longer have an E12 evap box on the shelf so all I can do is give the E28 numbers.

Box. 10 3/8 wide at the top. 9 1/2 wide at the blower cages.

As to the evaporator itself, 8" wide, the finned portion, not the tubes, about 7.5 high, difficult to measure without taking it apart, which I didn't want to do, ~3" deep, again a difficult measurement without disassembly.

E12s may have all used the same evaporator, but the rest of the parts weren't the same. Mid 77 on they got a different, likely larger blower. The condenser changed at least once, maybe more, 528i's got a different, more advanced, but not parallel tube condenser. 528i's got a different, much larger aux fan up front, and 2 speed, the lower of which was likely as much if not more effective than the single speed of the early one, and high speed really moves some air, though as much or more for aux engine cooling as more A/C.

So there's much more than just the evaporator to the equation, even the later condenser in 528s was probably inadequate even as it was better than before. An illustration, due to a replacement radiator I had a rub out on the fan switch in the radiator one time, on the highway, Utah desert in summer and blew the fan fuse. Even on the freeway, A/C performance was reduced and the evaporator froze up. I was just the tinyist bit low on charge, but the aux fan not working really complicated things. With a better condenser I doubt it would have been as much, if any, of a problem.

You can't blow cold air if you don't get rid of the heat. The Europeans in general I think fixated on refrigeration theory and needing to condense the refrigerant to liquid so it could evaporate off and make cold. Which they did. But IMO they underestimated just how much heat they had to remove from the system so the condenser portion was undersized. They just didn't understand 110+F in the desert, let alone in a 15 year old car, let alone in a 40 year old car.

BTW, I would be happy to sell my E28 evap box, and I think it does perform better, but I also think the biggest problem is the condenser, especially, repeat, especially if you're not running R12. The other refrigerants need a substantial condenser upgrade just to get back to OE capability, let alone 80s-90s standards. For whatever reason the evaporator doesn't seem to be the limiting factor with different refrigerants, it's the condenser.
It seems that early or late e12s, the regrigerant label still read 2.2 lbs or one kilo.

It is true that later e12s had larger sized condensers. The online OEM BMW listing sometimes gives the dimensions for the various years. The earliest ones were 12 x 19.5 in. I tried that original unit with r134a and a SD 508 compressor, it got down to 40F in warm weather. I then changed to the Vintage Air 12 x 20 in parallel flow unit with a slimline condenser fan in place of the original. The Vintage Air unit would easily have more cooling ability than even the stock condensers fitted to e23s. I also have experience with the same car running the original Behr hardware with r12. I would say that with whatever combination it worked well, and surprisingly you can use a tube and plate condenser with R134a, even though theory says that shouldn't work.

It should be noted that I used a r134a calibrated TX valve with R134a. The other thing is that the Sanden compressor puts a lot less load on the engine. You don't even notice its on.

Crucial thing is that you have no leaks and that you have the right level of refrigerant. A good window tint is important. Those material covers for the dashboard are also good, don't know if you can still get them for the e12 :?: I find the dash pod that some e12s have is good, because it brings the a/c exit point out of the sun, like an e28. I trimmed that pod too. When I reupholstered the interior 20 years ago, I put in a thicker headliner too. BTW a cloth interior is much better in hot weather than leather or vinyl. Like in, you can re-enter a parked car without burning yourself on the seat :!: :lol:

Those fold out sun foils, where the sunvisors held them in place, are good too. In fact I even got one for the back window. this all helps because of the e12's glass area. As proof of this I recently sat in a parked small white late model Honda on a 100 F day, without the a/c running, and it wasn't that bad. The car's limited glass area made the interior feel like a cave. This makes driving tricky because of the poor visibility, but the reduced glass makes for a cool interior. So I don't think the e12's a/c system was ever that bad, it's just the glass area that makes it seem that way.
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Re: E28 Evaporator core vs. E12

Post by Robert Bondi »

FWIW, this information was provided on an Ebay listing for the E28 evaporator core.
I've got an E12 complete evaporator blower box in a box preparing for this project, so
I might be able to close the E12 half of this question without the understandable headache
of disassembly for measurements.....


For BMW E28 E24 528e 535i 635CSi M5 A/C Evaporator Core Four Seasons 54626
Shipping
ITEM DETAILS
Specification
Part Type A/C Evaporator Core
Part Number 54626
Interchange Part Number 54626, 809008, 105328, EV5328, YE462, 1562205,
Other Part Number EV5319, 249462, 149416, 232092, 4711445, 55328
Core Depth IN 3.000
Core Depth MM 76.200
Core Height IN 9.625
Core Height MM 244.475
Core Width IN 6.875
Core Width MM 174.625
Description Evaporator Cores
Material Aluminum
O-Ring A Number/Desc [24608] / Green O-Ring
O-Ring A Quantity 1
O-Ring B Number/Desc [24610] / Green O-Ring
O-Ring B Quantity 1
Type Tube and Fin
Weight 5.38 lbs
L x W x H 18 x 10.5 x 6
Part # 54626
Mfg Part # 54626
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Re: E28 Evaporator core vs. E12

Post by Robert Bondi »

Mike W. wrote: Sun Feb 13, 2022 8:14 pm
BTW, I would be happy to sell my E28 evap box, and I think it does perform better, but I also think the biggest problem is the condenser, especially, repeat, especially if you're not running R12. The other refrigerants need a substantial condenser upgrade just to get back to OE capability, let alone 80s-90s standards. For whatever reason the evaporator doesn't seem to be the limiting factor with different refrigerants, it's the condenser.
I'll plan to get into my storage this weekend and measure the E12 evap box I acquired a few years ago for comparison.

Mike W. - I might be seriously interested in buying your E28 evap box. I've got to build an air conditioning system from scratch. I'm now
thinking that using E28 parts for the components on the interior side might be preferred for multiple reasons. I've got experience building the remainder of the system out in the engine bay when I converted my 530i to R134a, so I'll expand on that knowledge base.
Robert
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Re: E28 Evaporator core vs. E12

Post by tlake »

Robert Bondi wrote: Fri Mar 11, 2022 4:40 am
Mike W. wrote: Sun Feb 13, 2022 8:14 pm
BTW, I would be happy to sell my E28 evap box, and I think it does perform better, but I also think the biggest problem is the condenser, especially, repeat, especially if you're not running R12. The other refrigerants need a substantial condenser upgrade just to get back to OE capability, let alone 80s-90s standards. For whatever reason the evaporator doesn't seem to be the limiting factor with different refrigerants, it's the condenser.
I'll plan to get into my storage this weekend and measure the E12 evap box I acquired a few years ago for comparison.

Mike W. - I might be seriously interested in buying your E28 evap box. I've got to build an air conditioning system from scratch. I'm now
thinking that using E28 parts for the components on the interior side might be preferred for multiple reasons. I've got experience building the remainder of the system out in the engine bay when I converted my 530i to R134a, so I'll expand on that knowledge base.
The Hack Mechanic got a custom 3 row evap core made for his e9 coupe, that fitted in the existing e9 box. He said he wasn't sure if it made an improvement.

I did try my car with the stock condenser and R134a, before changing to the parallel flow unit, and it did surprisingly well with the original unit, even though theory says it shouldn't.
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Re: E28 Evaporator core vs. E12

Post by 528i-1981 »

The E28 unit would have o-ring fittings, correct? That's a big advantage - no sense wedding yourself to flare fittings and there's precious little space along the side of the console for bulky adaptors.
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Re: E28 Evaporator core vs. E12

Post by Mike W. »

528i-1981 wrote: Sat Mar 12, 2022 11:13 am The E28 unit would have o-ring fittings, correct?
Correct.
That's a big advantage - no sense wedding yourself to flare fittings and there's precious little space along the side of the console for bulky adaptors.
I always found flare fittings pretty easy to work with, I could just make my own. They are a bit of a unicorn in todays world though.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter
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Robert Bondi
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Re: E28 Evaporator core vs. E12

Post by Robert Bondi »

After a little delay, I took the measurements and gathered some pictures of the evaporator box
I have on the shelf. It was sourced as an E12 part, but clearly came off a 11/79 633csi. It looks like the
E12 evaporator and blower box does seem to check out as shared with at least some of the E24 lineage.

Here are my E12/E24 blower box measurements in inches. I attempted to account for both internal dimensions and external
dimensions separately where I could clearly measure the difference. I focused on the enclosure for evaporator and
expansion valve for the measurements.

H = 8.25"
W = 5.5" (5" internal)
L = 10.5" (10" internal)

https://www.flickr.com/photos/robertbon ... 0297675328

Robert
Robert
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Re: E28 Evaporator core vs. E12

Post by tlake »

Robert Bondi wrote: Sun Mar 27, 2022 10:33 pm After a little delay, I took the measurements and gathered some pictures of the evaporator box
I have on the shelf. It was sourced as an E12 part, but clearly came off a 11/79 633csi. It looks like the
E12 evaporator and blower box does seem to check out as shared with at least some of the E24 lineage.

Here are my E12/E24 blower box measurements in inches. I attempted to account for both internal dimensions and external
dimensions separately where I could clearly measure the difference. I focused on the enclosure for evaporator and
expansion valve for the measurements.

H = 8.25"
W = 5.5" (5" internal)
L = 10.5" (10" internal)

https://www.flickr.com/photos/robertbon ... 0297675328

Robert
Thanks Robert, will be saving all this valuable info. Car and Driver said out of the BMW 630CSi, Jag XJS and MB 450 SLC they were testing in 1977, they thought the 6 series had the best a/c :!: Such a shame R12 gas isn't available easily to classic car owners. From what the Hack Mechanic says, if you can find R12 it dates from pre 1994 times as NOS cans or recovered gas. :cry:
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