Small Car Performance, DIY Front A/C Installation

[MarkWard]

I made a change how the radiator fan switch operates. With my 82 van, I couldn’t figure out how to combine the vintage air and the factory 3 speed fan.

To simplify the “merge” I wired the radiator fan switch to complete grounds instead of power. I used the vintage air compressor switch to complete a ground and the trinary switch to also switch grounds. I used 3 Bosch 40 amp fog light relays to handle all the switching. Works really well. I still have the radiator high speed fan relay but it’s wired to energize with a ground from the fan rad fan switch. It sounds complicated but I’m a big fan of using relays.
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[ScottShelley]

Forgive me if this has been covered, this is a long thread. How many pound of R134 are most people putting in to the system. I don't have the small car manual and can not find it online. I put in 2.4 pounds and though running cool, I would like to run cooler.

Thanks

[MarkWard]

I can't speak to the volume, but what engine and compressor? You should post your low side reading at 2500 rpm. That correlates to the evaporator core temp. When the volume is unknown, you can get pretty close using the low side pressures. The vintage air unit comes with a warning that the expansion valve is tweaked to run lower pressures than expected on a conventional AC.
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[ALIKA T3]

[kourt]

Some values:

Vintage Air says 28oz R134 for a GenIV Magnum system (see page 4)
VAG (Bentley) says 47.6oz R134 (converted from R12 values)--this should be ignored with a Small Car installation, but is an interesting reference.
30-38 psi low charge, 98psi@90 degrees
troubleshooting, gauge readings Low Side/High Side
H/H: overcharge—bleed out
H/L: faulty reed valves in compressor
L/L: undercharge—add refrigerant
L/H: blockage

I generally pick a day 80 degrees or hotter, set a high idle (2500 to 3000 RPM), set a fan in front of the condenser, and charge to the lowest vent temp, and corroborate it with gauge readings that make sense.

Kourt

[MarkWard]

I fill the compressor crankcase with the specified amount. Others state you can fill it though the ports. I don't think that's a good idea. Remove the drain/fill plug from the compressor and pour out any oil thats in it. To be sure, you might want to pour in a small amount of your oil and pour it back out to sort of flush any oil that may not be compatible.

I believe Vintage air specified 15 psi on the low side was acceptable. Normally you'd expect to see around say 25 psi.

My TDI compressor had an internal valve that I had to disable in order to get the correct pressure. Its called a variable displacement compressor, but it's more of a bypass than a compressor that changes displacement. The vanagon sanden compressors don't have this feature, but I recall some Subarus do. That's why I asked.
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[ScottShelley]

28 OZ seems a little light considering the length of the hoses. It is interesting the the stock set up would take so much more.

[kourt]

What I've found is that I usually empty two 12oz R134 cans into the system, and then start really paying attention to my vent temps on the third can.

By the time I get about halfway done with the third can, the vent temps have bottomed out and are usually starting to creep back up.

Experience has taught me that a slightly underfilled refrigerant charge will perform better than on overfilled one, so nowadays I am familiar with the rate of change in the vent temp gauge (I use a digital multimeter with a temp probe) such that I can predict when the temps will bottom out, and stop filling when I feel it's at the bottom.

Other details: my refrigerant ports are at the front of the van. That means I can keep the engine lid closed and the van closed up for maximum cooling efficiency during the charging process.

kourt

[ScottShelley]

Good Information. Thanks

[ALIKA T3]

Thank you guys!!

Mark, I'll hit you up for the Tdi compressor mod, I too have a Tdi compressor, AHU style. I'd like to go ahead and do everything before filling....
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Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[MarkWard]

I actually stumbled across it on the TDI club forum. The valve is what attaches the reed plate to the compressor head. They were removing the valve and replacing it with a nut and bolt. I could not find a bolt that held the reed plate centered enough for me. So, I drilled and tapped the valve and installed a set screw. Basically disabling it. I then reinstalled the valve body. It's fairly straightforward when you get it apart. I was able to reuse the original gaskets.
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[Zeitgeist 13]

Is that mod mandatory? I have factory A/C with the stock ALH compressor, and it works pretty good, but I wouldn't mind improving output if possible.
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Casey--

'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik?

[MarkWard]

The vintage air uses and old style expansion valve. That type of valve was adjustable, though no one really adjusted them. There were 2 set screws in one of the fittings. I imagine Vintage air is setting them lower to work with R134.

The symptom on mine was I could not get a decent low pressure. This valve was really just a bypass of the reed plate. So, by eliminating it, you have returned it to the early style like the vanagon originally had.

VW was attempting to lessen the compressor cyclings by the late 90s. Eventually coming up with a computer operated valve on the CR TDI.

So, if your low pressures are good, probably no reason to do this mod. The later H type expansion valve the vanagons used is only available now for R134, but works with other gasses.
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[CarGuy8084]

Old thread but a lot of good information here. Two questions: How are you guys running your AC hoses. I don't like the idea of drilling holes in the unibody support if I don't have to. I would like to keep the hoses on the passenger side if possibly to keep the hose length down. My other though was to run down the center since there is a nice empty cavity there above the fuel tank.

Second. there were a lot of good wiring diagrams but they are hard to follow for me so I tried to convert the small car schematic to the easier to read connection diagram. Anyone see any problems with this wiring? my van is an 84 without AC so I'm interrupting the fan wire at the thermo switch like they say to do.

[ALIKA T3]

You're gonna have to cross over at some point with the hoses. Maybe best is to do it above the transmission.
I ran mine with the power steering lines pretty much and above the UCA to the other side of the beam bc I relocated my evaporator a bit. I think you could keep going straight otherwise. Mind you I have a Syncro, so no fuel tank to avoid, so prolly best like dealer added AC but on passenger side.
_________________
Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[VanMorrisSon]

Hoping for some advice. I REALLY tried to not have to ask any questions as I know almost every question has been answered in this 31 page thread.

I finally got everything in and wired up. In my charging process, I pulled close to 30 inches of vacuum for over 16 hours, then sat with the pump off an gauges attached for a few more while I bled the system and coolant. I added one can of refrigerant, then a can of this oil+refrigerant stuff so I can bring the system's oil level to what SC suggests (it's only an ounce can at this point), then I get into my second 12 oz can of refrigerant and I start noticing this cloud of vapor/steam filling up the van. Turns out, the system is pissing out of the Trinary switch in the top of the drier. Did I not torque it properly? How tight does it need to be? I was under the impression it needed to be hand tight then a 1/4 turn.

If the high pressure side was open at all, would that cause the trinary switch to fail?

I assume now my only option is to have the system evacuated, replace the switch and charge it again. Is this accurate. Thanks in advance.

[djkeev]

On my 90 A/C system rebuild I had modified the stock VW switch mounting because I changed all of the hoses.

Like you I pulled a vacuum overnight and then turned everything off and it held vacuum telling me the system was leak free.

As I charged it the modified mounting could not hold pressure and leaked.

Make sure your switch matches the mounting nipple thread and has the sealing Oring.

Order a new switch. PAG oil the sealing ring.

Anyway......
In short, yes, they do fail under pressure but hold a vacuum.

Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[khughes]

[VanMorrisSon]

Thanks Dave and KHughes. In an overly convoluted process, a simple answer makes me feel a lot better. The thread match makes sense as I could get it threaded a decent depth, but there was no 1/4 turn more left - never seemed to 'seat', but I thought that was just how the trinary switch worked.

And thanks for the charging info, it's helpful to know it's a little more forgiving.

Rich

[joetiger]

For those of us running the Vintage Air Gen II with non-illuminated dials, Vintage Air has a new backlit control setup:

After fumbling for the controls on my long road trip, I'm considering moving mine from their current location on the lower section of the dash to the radio opening and moving the stereo somewhere else.

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Joe T.

'86 NAHT Vanagon GL Syncro/ supercharged ABA 2.0 "Pigpen"
'04 GTI 1.8T
'04 Golf R32

"get metaphysical with it. if it's simply a means to get to and from places, it will let you down. if it becomes your zen, it can't fail you." -dabaron

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