T4 Air Conditioning Modernization

[MGVWfan]

OK, one of the projects I'm working on (slowly) is bringing the Nomad's A/C up to modern standards. Ray's had some ideas, and I'm going to start this thread to document what I'm doing, along with whatever you folks want to add.

Here are some of the considerations...

The VWoA port installed A/C (the "better" version) uses a Borg Warner/York 206 compressor, a front-mounted condenser under and behind the front bumper, twin axial-flow condenser fans, an underdash evaporator housing drawing interior air only, and what seems like miles of non-barrier refrigerant hoses, with flare fittings.

Problems with the original system:
>In cool weather, no way to draw in outside air to keep from having to engage the compressor when the temps are pleasant
>The entire system draws enough current to overwhelm the alternator's ability to keep the battery charged with long idling
>The original compressor drive belt is a strange width (9.5 mm), not available in the required length any more
>No way provided to stabilize idle speed when the compressor is engaged
>The compressor bracket to fan housing mounts use four rubber bushings which fall apart with age and heat
>The original system uses R-12, which is not economically practical for use in the Type 4 due to the quantity required (over 2 pounds)
> The original York compressor displacement (6 cubic inches) is not readily available in new or rebuilt York/CCI compressors
>The A/C controls are not integrated with the heat controls
>No way to direct chilled, dehumidified air to the windscreen for demisting
>Even with 6 cubic inch displacement, the original compressor does cause noticeable engine power loss at high head pressures (making idle speed maintenance even harder)
>The original Ogura compressor clutch is NLA
>The receiver/dryer and hoses are in the right front wheelwell, bad news for road debris and accessability
>No high or low pressure control switches to protect the system
>Full system current (a bit less than 25 Amps) flows through the main switch, which is NLA
>The system is protected by a self-resetting 30A circuit breaker vice fuses
>Replacing the compressor belt requires removing the engine cooling air boot (not a trivial matter on a Variant), and removing the engine blower
>Setting belt tension is fiddly, requiring contortionist skills and three or more hands

Note that the situation with the 411/412 Variant is the worst, due to the compressor's location. It appears to be easier to get to the compressor on the sedans, and the T4 powered bus is like the wide open spaces in comparison. Also, the engine cooling air inlet boot on the sedans is much easier to remove for belt service, and the T4 powered buses have the best situation of all. So, whatever I come up with for the Variant will work for the sedans, and the engine-compartment stuff (and electrical mods) should work with the T4-powered buses, too.

Here's what I have done, and plan to do (pictures and part numbers/parts sources to be supplied...):

>Add fuses and relays to separately power the compressor clutch, the condenser fans, and the evaporator blower and control system (done)
>Replace the compressor-end hose fittings with barb type fittings to allow system testing (the original crimped-on fittings leaked profusely, and no other fittings leaked at all...must be the heat in the engine compartment) (done)
>Flush the condenser, evaporator, and hoses (done)
>Check the expansion valve (done)
>Overhaul the original York 206 compressor (done, retaining original reed plate, crank, pistons, and rings in freshly honed bores)
>Replace the compressor bracket bushings (done)
>Reinstall and performance check (in work)
>Install high pressure cutout switch (in work)
>Develop an "idle-up" system for the D-Jet EFI system (in work)
>Evaluate cost/benefit of replacing original hoses with a combination of rigid lines and barrier hoses (in work)
>Evaluate possible replacement compressors (in work)
>Move dryer to front boot (trunk) (to be planned)
>Increase condenser fan airflow while reducing current draw (to be planned)
>Evaluate addition of extra condensing area (to be planned)
>Design all-new evaporator housing with airflow controls for defrost air supply and either outside or inside air suction (to be planned)
>Develop interlocks to prevent both A/C and Eberspaecher from being energized at the same time (to be developed)

COMPRESSOR CONSIDERATIONS:

>The original York 206 is smaller displacement than the usually-encountered replacement (10 ci), and the larger compressor is too large for efficient operation in the T4 system
>The compressor rotates CCW (anti-clockwise) vice the usual clockwise, due to the mounting position and T4 engine rotation direction
>The CCI/York 206 case has to be shaved to prevent interference with the body, making it not interchangeable with off-the-shelf CCI new compressors and rebuilts (unless they came from a T4 originally, very rare nowadays)
>The small diameter crank pulley means the clutch pulley must be equally small to maintain adequate revs at the (original) compressor at idle. The 4.75" Ogura clutch was special-order even in the 70's, and is NLA now. Most survivor clutches are pitted from rust and worn, making them almost useless
>The York/CCI compressor fits the available space perfectly (after case shaving) due to its unique form factor. Most modern compressors are longer and shorter, making finding a compressor that fits tough.
>Some new compressors are sensitive to excess heat, and the T4's compressor location is right above the muffler, which complicates compressor selection
>The original compressor and clutch place the drive belt very close to the mounting plate, much closer than allowed by many modern compressor designs

More to come.

[albert]

allo, mgvw, wy you d,t look for 12 volts compressor , , more simple and more safe for the gaz leak , i know they exist on the maket , example ,,, danfos ,, they sale différent compressor for to instal in the sheep , for fridge or airconditionner , or freezer , the price appx for compressor with 10k ,btu is appx 1k$ list, but you save on the instalation ,, and you can install heathing pump , in the summer he geeve you fresh air and in the winther the systhem revers the gaz and he geeve you heathing ,,, alb.

[MGVWfan]

I had that thought Albert, but an electric compressor that pumps the required mass flow of R-134a at the expected pressures consumes something like 2 kW...at 12 Volts that's 167 Amps, far more than the alternator can produce. If an engine driven compressor consumes 4 hp (as an example, about what a Sanden 508 consumes at 3000 rpm), that's 4(0.746), or 3 kW, even worse if you try to drive it with an electric motor.

[raygreenwood]

The idle up problem is not too hard to solve, but is difficult to adjust. The problem is this. A normal solenoid throttle kicker is not good...as it put the TPS in a bad positioon as far as start point and open/closed contacts. It makes for an ugly flat spot off the line. The best way.....is a very very small vacuum bleed via solenoid directly at the mps. Ray

[dphdo]

Hi all! Just my 2 cents worth on this topic: A problem I am having is the heater pipe from the heater box up through the engine tin (the pipe where the blower motor attaches) will not fit on the side of the compressor. The pipe hits te compressor pulley. Also, how does one now run the heater "pipes" (for lack of a better word) through the engine compartment in the variant to the passenger side heater duct from the blower? Again, the compressor is in the way.

On a happier note, apparently there is a direct replacement for R12 (not 134a) that you just put into the R12 system without any conversions.

Finally, regarding the drier, if you visit the site for reVolks, go to the area where they restored a green 412 variant, I noticied in their photos of the trunk area that the a/c drier was installed in there-perhaps some ideas may be generated from that picture.

Finally, I used a company named I.C.E. out of California, they were very helpful to me.

SMILES
Dale

[raygreenwood]

Things like the dryer are not difficult at all. There are two main types. One has a bladder or resoivoir....the other does not. I can't remember all of the difference, but capacity is not a big issue....and almost any dryer can be used as long as its fittings are compataible with both your lines and the refrigerant.
I am slowly working on a system for my car. It will be a ceiling mounted console...just aft of teh headrests. It will use an evaportaor coil and expansion valve from a golf 3. The lines will run up the "C" pillars. I am using two small condensors linked by a pipe....in teh spaces just forward of the front wheel wells. Ray

[albert]

hi, ray , i geeve you my oppignion for the 412c air conditionner, i work on that , for my 412 ,, i see in my ref.ac. books , step up power booster 12 to 110 volts ,good for 1800watts , they said in her pub description , this machine is good for 6 hrs for to use domestic fridge at 600watts before recharge the 12 volts spécial battery include in the machine , they sale that 600.$ and if we go with this idee we can put ac compressor at 110 volts for to run 412 air cond. more safe for the leak plus the systhem can run wend the car is stop for short time examp. 1 hrs and we can install split charge relay on the car battery wend the car alternator run he recharge the air con. battery in the same time , and we have in the 412 the place for 120 amp. alternator , i thing my idee is not to bad for good air cond. in the 412 ,,, alb.

[raygreenwood]

I would have to sit down and figure out what difference it would make to the alternator sizing...and then what that extra drag would mean to the engine in power loss terms. This electric motor could also possibly do better with either production or reduction gearing to remove peak load.

Or.....and this was an odd thought......
But...last week, I was looking at the small.....really small ...4 stroke Honda engine on my dads new dirt tiller for his garden.
Its about 4 horse...and really quiet. It takes up a space about



8" x8" X 10". It has about 4 hp. He bout the tiller complete ...new for about $225 at Lowes or Homey depot. Hmmmmmmmm. Put a bigger muffler tube and an electric start....and it could run an AC compressor.

I mean hey.....we are keen on a gas heater...why not gas AC? Ray

[albert]

yes , ray you have one model of solution for air,con. but with the price for the gaz , we look for the most chip running solution ,,, if i compt the price for univarsal step,up power booster and the universal (standart ) électric ac compressor ( rotatif ,not with the piston ) we can do a good a.c for the car , plus we can do heathing systhem with the same a.c. comp., with 5k btu we are ok for to maintain a good temp in the car, the heathing radiator in the wather cool car is appx. that , and a small comp. for home windhow ac. is appx. 5kbtu and it is good for a room 10x 10 but your mécanic ac compressor with small motor that can make good solution ,, one thing with the électric comp. the receever gaz accumulator and the expention valve is not nécessaire , we can use capilary tube 0.020 inchs id ( all depend of btu h ) and the systhem is more simple and more safe for the ref.gaz leak ,,, all that is only my small oppignion , we make reflection on all that ,,, alb.

[MGVWfan]

Well, after futzing about (technical term) with the PC for a month after three sets of storms killed two UPS boxes, I think I'm back up.

Albert, bonjour. If you start with the mass flowrate of refrigerant needed to be moved at the highest discharge pressure to supply about 1.5 tons of refrigeration, and look at how much power a compressor will take to flow that much refrigerant, you end up with a minimum of 4 hp. 1 hp = 746 Watts, so with losses that ends up being something like 3.6 kW. Even if the inverter is 100% efficient in converting 12 VDC to 120 VAC, you still end up with 300 Amps at 12 Volts...way, way too much for any reasonable alternator. Ray's auxiliary power unit (APU) idea isn't too far off the mark, then! A trunk-mounted APU generator!

Dpdho...I took a look at some of those replacement refrigerants other than R-134a, and decided I didn't want a blend that had to be charged as a liquid, and discharged completely when servicing (no topping-off, it changes the blend's composition due to the different boiling points of the constituent gases). R-134a may not be the optimum refrigerant for a retrofit, but it is readily available and fairly cheap, and fittings, O-rings, gaskets, compressor parts, etc. have been tested with it, so I figure I'll take one variable out of the mix for now.

A problem I am having is the heater pipe from the heater box up through the engine tin (the pipe where the blower motor attaches) will not fit on the side of the compressor. The pipe hits the compressor pulley. Also, how does one now run the heater "pipes" (for lack of a better word) through the engine compartment in the variant to the passenger side heater duct from the blower? Again, the compressor is in the way.

Hey, that's easy to fix! Even the VWoA port installation instructions tell the installer to "knock a big dent" in the heater air tube, to clear the clutch. If you're using one of the OE York R206L compressors with an Ogura 4 3/4" clutch, you shouldn't need to dent it too badly (something like 1/2"). If you try to use a "longer" clutch, or a compressor that sticks out further, you'll have to "dent" the tube more. As for the flexible ducts, well, VWoA had a special replacement air tube fitting set SPECIFICALLY FOR T4's (and maybe even for Variants) which changes the hose routing to clear the compressor. Here's a link to the "tee" that goes on the left side tube...

http://www.thesamba.com/vw/forum/album_ ... _id=196801

...and the blower with its "elbow"...

http://www.thesamba.com/vw/forum/album_ ... _id=196800

http://www.thesamba.com/vw/forum/album_ ... _id=196799

http://www.thesamba.com/vw/forum/album_ ... _id=196798

There's a short flex hose line from the end of the elbow to the side of the "tee", and the line to the right side heater box comes off the top of the "tee". I hope that helps.

I just tore up my heater air supply tubing trying to work in the engine compartment, so I can't take a pix to show you how to route it right now. It can be done, just try using some of that foil and Mylar air preheater tubing from the FLAPS and "flattening" it a bit to clear the engine lid. The two fittings shown above are made of thin plastic, I'd bet someone could fab something up out of sheet brass or steel to replace them.

I'm planning on moving the RSD out of the wheelwell into the front trunk (boot in British parlance) when I replace the lines sometime. I also want to go with rigid lines except for short lengths of flex hose when needed (like at the compressor, the condenser, and the evaporator).

I've found a candidate clutch (OE application is a John Deere agricultural something), it's 4 1/2" diameter, the groove is right at the compressor body, etc., and it's used on the newer Nippondenso 10PA series variable-displacement compressors. I found a candidate compressor, too, tangent (pad) mount, 150 cc max displacement, used on LOTS of recent cars, so I've ordered the clutch for a look-see. More when I get it in!

[MGVWfan]

Well, my digicam is inop, or I'd post a picture of this. I found a good candidate replacement compressor! It's a Nippondenso 10PA15C, used on millions of Toyotas and a few MoPars and Mitsus, along with some John Deere agricultural equipment. It appears to fit the space allowed, it's not an overly large displacement compressor (should match condenser capability well), and there's a clutch available new that fits in the space allowed. It's not veriable displacement, oh well, but so far so good. I will be modifying the VWoA York mounting plate to allow mounting of the compressor I snagged from the junkyard today (from a 1994 Toyota Celica). I also need to figure the hose connections out (it has a pad-mount manifold bolted to the top of the compressor, I know somewhere there's a suitable manifold for flare or tube o-ring fittings, I've seen one, I just can't remeber where...).

[MGVWfan]

Well, my digicam is inop, or I'd post a picture of this. I found a good candidate replacement compressor! It's a Nippondenso 10PA15C, used on millions of Toyotas and a few MoPars and Mitsus, along with some John Deere agricultural equipment. It appears to fit the space allowed, it's not an overly large displacement compressor (should match condenser capability well), and there's a clutch available new that fits in the space allowed. It's not variable displacement, oh well, but so far so good. I will be modifying the VWoA York mounting plate to allow mounting of the compressor I snagged from the junkyard today (from a 1994 Toyota Celica). I also need to figure the hose connections out (it has a pad-mount manifold bolted to the top of the compressor, I know somewhere there's a suitable manifold for flare or tube o-ring fittings, I've seen one, I just can't remeber where...).

[R2.0]

Does it look something like this:

[raygreenwood]

Looks like a golf compressor. Ray

[dr. no]

Is a Golf compressor what you use to play 9 holes instead of 18?

I just got my home-brewed system fired up on the Ghia today (T4 conversion) and will post Pics in the 4rum (after I take them). Gotta wait till dark to look for leaks, too.