Underdash a/c unit for a 412 question

[1974vw412]

Has any one ever used one? Does it cool down the car?

[hazetguy]

Post a wanted ad in the classifieds, not the forums.
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[OB Bus]

And welcome to the forums!

H-Guy: OP was not trying to buy one, just asking if anyone had experience with one.

OP: I know it is kind of lonely in the 411/412 forums but this might be better posted there.
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[1974vw412]

Great idea, thanks for the advise.

[raygreenwood]

[raygreenwood]

Yes I have used one of these units...yea...in their stock form with the whole system they worked well.
That being said they used a massive, heavy compressor that robbed a ton of power.

If you rebuild the system get a Sanden style or newer compressor for less than half the power drain....get all new seals and hoses and use origibal R12 freon.

The design and area of the condensor does not work as well with R134....and even with modern o-rings the type of original couplings were not ideal with the smaller molecules of the R134.....but it does work.

If you use R134....you should get a new compressor no matter what.

You should drop by the 411/412 forum. No offense..... ....but those who do not own or drive them know virtually nothing about them.

We have lots of resources for suspension upgrades, engine, heater system, transmission, brakes etc. Drop by and introduce yourself. Ray

[EverettB]

Moved...
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[19super73]

My 73 had that set up but it was not charged and the compressor was missing. Meh, roll down the window.
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1974 412 Variant
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1984 Vanagon

[raygreenwood]

The sad thing about AC in the 411/412...and holds true for "most" ACVW except I think the l;late bus...is that these were all dealer installed units...and the amount of pure hacking to the chassis to install the evaporator, screw in the components etc....was horrible. Ray

[1974vw412]

Thanks for the information. I'll dig though the how to's. I just purchased a 74 412 wagon that needs some tlc. I have been looking at aftermarket under the dash ac units but the ones back from the seventies look much better. Living in Atlanta, you really need ac or just forget about driving during the warmer months; heavy traffic all around town. If you ever come across one, please drop a line.

Again, thanks for the information!

[raygreenwood]

[1974vw412]

Ray, you are a better person than me; lol. I am from PA and have not gotten used to the warm weather.

[raygreenwood]

[TeamChili]

I may have some VW a/c parts coming up for sale soonish.
The a/c in my Bradley probably never worked, but I think all the bits are there.
At a minimum there’ll be a Type 4 compressor mount and pulley that’ll be of use to someone.

[1974vw412]

Ray, I'm from the other side of PA, Pittsburgh. Thanks for the information on the ac. Imreally appreciate the insight. I'm looking forward to retrofitting the unit in, it should be fun.

Team chill, I am interested in purchasing the parts. Let me know when you are ready to get rid of them. Thanks

[anglodeutsch4]

Until the Nomad dropped a valve seat in 2010, I had functioning VW port-installed A/C like your picture on it. I converted it to use R-134a and POE oil. These systems were designed by a company VWoA ended up buying (in Dallas IIRC), and appear to have been installed at the port of entry. I have a sticker on the glove box door attesting to the VW facility at the Port of Houston having installed my Nomad's system.

1973 412 Variant with a (formerly 1.7L) 1.8L. I figured out a way to fit a Nippondenso 10PA15 tangent-mount compressor on the port-installed compressor mount bracket with hardware store stuff. The original York 2-cylinder compressor was not rebuildable...so, I had to go with something else. A Sanden 508 type will fit IIRC, but I had this former Toyota compressor, so I made it fit. I found even with the smallest compressor pulley I could get (4.5" OD), I could not spin the compressor fast enough at idle to keep up with the cooling load here in Houston. The port-installed "chin spoiler" evap is also a limiting factor, until you get up to ~25 MPH, not enough airflow to keep head pressures reasonable, so you have to slightly undercharge the system. Final problem, the 55A Bosch standard alternator could not keep up with the ~30A load from all the fans, plus the rest of the car's requirements at idle, so to get an A/C system to run well on a 412, I think there are three things to work on...
1. More alternator output at idle (newer style alternator with a smaller pulley)
2. Spin the compressor faster (maybe work out a poly-V belt drive at the aft end of the engine, similar to the alternator drive
3. More condenser surface area and airflow (condenser in the spare tire well, and another near the transaxle under the car, or Ray's suggestion of in the "valence" space up front).

You will DEFINITELY need to put together new barrier style hoses with Beadlock fittings to keep the refrigerant in.
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Lane
MGVWFAN (STF)
anglodeutsch4 (Samba)
73 VW 412 (the Nomad, dropped valve seat land now, argh!)
67 MGB (Built-In Rust from Abingdon)
2002 NB TDI (40 MPG)
2009 JSW 2.5 (love it, love it, love it!)

[tlake]

Anyone going to R134a should put in a modern parallel flow condenser. They deal with the extra heat generated by the greater pressure of R134a gas. Vintage Air make a great unit. As a side benefit such parallel flow condensers are wafer thin, allowing easier installation.

[raygreenwood]

[tlake]

[anglodeutsch4]

Ah, welcome to the Type 4 fun!

Yeah, about that parallel flow condenser thing...the "chin spoiler" condenser (at least, the one port-installed in my 1973) is a serpentine design. Big rectangular cross-section aluminum bars, with 6-7 tiny little parallel channels from one end of the tube to the other. One tube all folded over on itself, with hot gas going in one end, and less-hot liquid (hopefully) coming out the other. Lots of micro-stamped aluminum fins brazed to the square tube. With the very long and very short area available, I'm not sure if the 4-5 parallel tubes you'd be able to squeeze in with a parallel flow microchannel design would perform any better than the one serpentine microchannel tube. Academic exercise anyway, since it looks like no one makes a parallel flow microchannel condenser in the dimensions needed to replace the serpentine condenser in the "chin spoiler"...and I've looked over the last 10 years, quite a bit. Vintage Air makes lots of nice stuff for Buses and Beetles, but nothing really suitable for the Type 4, especially the Variant. The Buses can mount lots of condenser underbody and not have it get damaged, the Type 4 really can't due to being lower. The Beetles and T3's can mount condensers above the transaxle, but that's where the Eberspaecher is in the Type 4...and the 003 automatic is bigger than the Type 1/3 transaxle in any case.

The problem with the 412 Variant IMHO is getting enough surface area and airflow. The "chin spoiler" condenser uses two 4-blade 8 Amp fans to the left and right of the spare tire well below the front trunk, to pull air from the rear of the condenser and exhaust it underneath the car. Standing in traffic at idle, those two little fans barely produce enough airflow to remove the needed heat to keep R-134a condensed. I suspect the airflow and condenser were barely adequate in summer, in traffic, at rest with R-12, and R-134a just makes the problem worse. And, I'm not sure any current condenser design would do any better. It's a fundamental space limitation.

There are really no other places for extra condensing surface area, other than the spare tire well, a very small space in front of the rear axle carrier, and in the left and right engine air inlet plenums in the rear fenders. The sedans have space in the engine bay, but then you run into another problem...potentially heating the engine cooling intake air. The rear fender mounting areas in the Variant have the same problem. With the T4 engine, I would be very hesitant to do anything that raises the engine cooling air inlet temperature, especially in the summer...when the A/C's going to be working its hardest!

As for the 'Vair's condenser location...I have no idea if the 'Vair had cooling troubles, but the idea of dumping an extra ~25K BTUs into the engine cooling air inlet stream for an air cooled engine does not inspire confidence in cylinder head longevity Waterpumpers can tolerate the temperature increase, aircoolers, not so much. I know Porsche did it, too, and I would like to see some airflow and temperature figures, and some refrigerant P/T figures to see what the real effect on CHT and A/C system performance was from that installation.

I do know Griffiths has additional fenderwell condensers for the 911/930 to increase condensing area in their Kuehl setup. That's not a good option with the 412, especially the Variant, the Eberspacher and heater hoses take up a lot of the rear fenderwell area...the front fenderwell area appears to not have enough area to me to mount much more than a receiver/dryer. Now, the spare tire well holds some promise, cut a hole in the bottom and mount a small condenser there, with a fan on the bottom, and a metal plate divider above, and vents cut in the aft end. That might work.

BTW, I don't think the evaporator is an issue, it's a big copper tube type, and appears to be able to boil all the R134a you care to feed it. Just change the TXV out for one charged with R134a, and you're set. Now, interior airflow, that is another topic for another rant
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Lane
MGVWFAN (STF)
anglodeutsch4 (Samba)
73 VW 412 (the Nomad, dropped valve seat land now, argh!)
67 MGB (Built-In Rust from Abingdon)
2002 NB TDI (40 MPG)
2009 JSW 2.5 (love it, love it, love it!)