Piecing together an A/C system

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ChargerST

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Posted this on FBBO before but didn't get any answers besides get a kit from Vintage Air but this is not what I want for two reasons:

a) cost - I live in Europe an shipping, taxes, customs add 8 to 900 dollars on top so I'll try to source parts locally.

b) I want to be able to get replacement parts locally.

I want to add A/C again to my factory air car (was removed by a previous owner) and have some questions:

I plan on building a custom setup and the only parts I already have is the original A/C heater box and a NIB SD7H15 genuine Sanden compressor. So I still need a condenser and I know that I should use the largest I can fit.

What size is the radiator opening on a 26" radiator car (car is in storage and can't measure myself)?

Is a parallel flow still the best condenser type to use?

The ports on the compressor are 7/8 threads - how critical is it to match that to the fittings, hard lines etc? Most condensers have smaller ports. Or should I try to get everything the same size (is a smaller port/fitting an unwanted restriction?)?
Some OEMs have condenser outlets as small as 5/16..

What about condensers with integrated dryers? Any advantage on having a separate dryer?

Thermal expansion valve (TXV): any suggestions for that part? Vintage air has electronic valves iirc - can these be fitted to a custom setup easily as I read that they are superior over TXV...

I might have to use an R134a replacement refrigerant - which non flammable would you use? R513a?


Thanks
 
Actually you MAY NOT want "the largest condenser" you can get.

There is, basically 3 types of control devices feeding the evap. Orifice, capillary tube, and TXV (Thermal Expansion Valve) Only a TXV will give you control of the system to the point that you can truely use an oversize condenser, ESPECIALLY when you are/ probably are using mismatched components.

An orifice/ cap tube control can allow over feeding the Evap under some conditions, such as when the interior has cooled down, AKA the load is less. By the same measure, a too large/ too small condenser can cause similar problems, IE cooling the refrigerant so much that it "floods" the suction side, or won't hold high enough head pressure to properly operate

If components are "far enough" off sized from each other, and or if the system is charged a bit on the tall side, you can end up with liquid returning to the compressor. There are lots of variables--the OD weather AKA temp and humidity, the ID temp and humidity (the load), the sizing of all three major components, compressor, evap, and condenser, and as mentioned, the control

Having/ not having a suction accumulator and or receiver also has an effect

In my opinion, you would be better off picking a donor setup you think you can adapt, and use those major components. You may be able to cross reference an original compressor to what you have to get some idea of it's capacity.
 
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The condenser I plan to use is roughly the same size as the one in the Vintage Air kit (26×18) so I guess I'll be fine. Will use a TXV as well.
 
Im putting "factory" ac on an 85 D150 that originally came without ac as we speak. Junkyard, swap meets, craigslist, and ebay have been my go to's. I still need a condenser and a drier, but the ac part of the project is on hold because of some needed bodywork I have to do before I put the ac box back into the interior.
 
Presumably you have brackets to mount the Sanden compressor. Easy for a V-8, not so for a slant-six, but there is a long post here for those options. I think a larger condenser is always good, even if bigger than the radiator opening and parallel-flow is 30% more efficient. An integral filter-drier simplifies plumbing and mounting. The dealer retrofit condenser in my 1965 Newport sits in front of the radiator opening, overlapping slightly, with rubber seals around it to ensure all air flows thru one-way. An add-on electric fan for the condenser helps when sitting long as stoplights. No need to match fittings at each end of the hose, they just need to fit the hose size. Standard today is O-ring fittings, #10 at suction and #8 at compressor outlet and condenser inlet, #6 at condenser outlet and filter (liquid lines). Use barrier-hose (Viton liner). I have the Master-Cool ferrule crimper, but can suffice using Oeticker stepless ear clamps which still looks factory, or even Breeze smooth screw clamps.

Thermo expansion-valves (Mopar and most today) are better than orifice tubes (GM?). I think you can still buy Mopar style copper expansion valves with AN flare fittings and a thin copper sense tube, though I would prefer O-ring fittings (available?). New cars use an expansion valve block w/ face O-ring, but finding matching fittings might be hard. Your existing climate box w/ AC evaporator should be fine. If you get inside the box, you could add a Ranco anti-ice switch (older GM, my 1985 M-B). It is wired to simply disable the compressor clutch when ice, but Mopar never thought needed. If you add a pressure switch at the filter (smart), get a binary type to disable the compressor if either too low or too high refrigerant pressure.

Re refrigerant, seems you have been reading the humorous horror stories about HC refrigerant being "explosive". Spread by AC techs who don't want people easily maintaining older systems and hobbyists who never took engineering courses in combustion (me, need oxygen). I use Duracool (Envirosafe, others). No reported fire in millions of cars using it for decades, other than an Aussie AC tech who fabricated a fire. A 6 oz can is laughably dangerous. Fear carrying a newspaper in the cabin more. Plus Germans (and Austrians?) have HC refrigerant in their home refrigerators (kool-case). Works even better than R-12. R-134A is being outlawed. Can't use R-1234yc, which costs $$$ anyway. PAO 68 is the best oil for any refrigerant.
 
I'd go with the 134 for freon.
On the expansion valve setup most moparts used that setup, there were a few that didn't, but they are much newer. Cars like the 2010s avenger and I believe some of the 97-02 trucks used orifice tubes but we're "captured" meaning that to replace the tube, you had to replace the whole line. Stupid.
Many used a capillary tube within another tube (like a sheath mounted next to the actual ac line) for freeze up protection. I've seen that on F M J cars (diplomat etc) and some of the 80s trucks. The new lines I bought for my 85 D150 have provisions for it (aftermarket lines but factory configuration)
seeing how it's wired in, by the factory wiring diagram for my own truck, it's in series (think Christmas tree lights) with the "hot" wire to the ac clutch.
 
The problem with a non-standard alternate refrigerant is no professional shop would be able to service it. Maybe not a concern if you do it all yourself, and are comfortable and familiar with HVAC testing, evacuating and charging. 134a was the standard from '93 ish to 2016 ish, 1234yf is the standard for now.
 
OP is in Austria. EU banned R-134A for new cars in 2013. https://europe.autonews.com/article/20130824/ANE/130829947/toyota-switches-back-to-banned-refrigerant-in-europe . But, it can likely still be bought to service older cars. Caused a big stink after a M-B test showed R-1234yc can burn to produce extremely dangerous HF gas (etched glass windshield, worse for your cornea). Not that R-134A is better since it forms deadly phosgene gas (used in WWI). While the refrigerants themselves don't easily ignite, a leak comes with an oil spray which will ignite if it impinges on a hot exhaust (M-B test w/ turbo). Also, if the engine is still running after a front crash breaks the condenser, leaking refrigerant is sucked into the engine to burn. Firefighters have been gassed in passing an exhaust pipe.

Venting HC refrigerant is no worse for the planet than cow-farts (a major concern), but illegal to vent any refrigerant per EPA. So, watch for an EPA drone hovering if you do have to vent it. For 20 years, the EPA has still been "evaluating" HC refrigerant, reportedly because it can burn in air. It is illegal to directly convert from R-12 to HC. You must first install R-134A, recover that, then install HC refrigerant. Again, watch for those drones. If in CA, consider that the western U.S. hasn't had an average temperature increase since records began, nor most of the Pacific, equator, and southern hemisphere. Most temperature rise has been in the Arctic (4x) to drive up the global average, and in northern Europe. Using R-134A (bad for global warming) risks causing the Inuit to shed a layer.
 
Thanks Bill, great information! There is a local company that specializes in all sorts of A/C systems not just cars (I try to avoid automotive A/C shops as most technicians there only have a very basic knowledge of A/C systems) but I haven't been able to get ahold of them since they are so busy (apparently they only have 2-3 employees and the office is only open when they are not working on something).
Regarding fittings I plan on using Manuli Frigoclic (comparable to Aeroquip E-Z A/C fittings but available locally) - and their hoses:

Screenshot-2023-04-20-112314.jpg
 
Those will work and appear to be standard O-ring type. Their clamps are Oeticker stepless ear-clamps (or copy), in a twin arrangement. When I use Oeticker clamps, I also use two and stagger the ears 180 deg. I've used them when I don't have a ferrule die for that size or working on-car where I can't get the crimper on the hose. I use nail-puller pliers w/ long handles, rather than their special crimp tool. Might also find PEX clamps which fit (Home Depot) and use their pliers tool. Any barrier-style AC hose will work. I prefer reduced-barrier size when it fits my existing Master-cool ferrule crimper dies. I bought hose and O-ring fittings on ebay. Still have rolls of #6 reduced, 8, 10, & 12 reduced after installing AC in my 3 old Mopars and re-hosing my two 1980's M-B (re-used those special fittings).
 
The Frigoclic actually have two types of fittings: the "field repair" oeticker clamps and the crimper type (which I want to use - the local hydraulic supply store should be able to crimp them for me). As far as I understand their barrier hoses are all reduced diameter.

Any suggestions for a (type of) dryer or are they all pretty much the same?

What about compressor orientation? Should the connections point up or does it even matter? I would assume it doesn't really matter much.
I want to mount the compressor on the passenger side below the alternator and the hoses would exit towards the inner fender.
 
I used generic filter/driers on mine, with #6 O-ring fittings. One I had was strange because the thread was a different size than standard #6 nuts, so couldn't use it. Otherwise, consider the orientation of the in and out fittings. Some are 180 deg and some 90 deg. I mounted most in front of the radiator support. I also added a binary pressure switch, wired in-line with the AC clutch coil control (to gnd). The clutch signal comes from the knee-knocker box and could drive the clutch directly, but I use an underhood relay (one of 7 in 1990's Jeep box I used). Most filter/driers have a port to install a Pswitch (screw plug). Another idea is to add a temperature switch on the filter-drier to actuate an e-fan in front of the AC condenser. I used one for my M-B cars (mounts w/ integral screw).

I have read of the dessicant pouch inside a filter-drier degrade to send dessicant beads downstream. I don't know if just old or a cheap design. You would only know by cutting them apart, as many do in oil filter reviews. Perhaps some state they have a metal screen to avoid that risk. Re hose orientation, you can buy various Sanden heads (~20) on ebay for ~$20, with different fittings and orientations. Don't remember if for 5-bolt or (older 508) or 7-bolt (SD7), but recall the later. I did for my M-B to get a "GM Pad" on the proper side. You can also tilt a Sanden up to almost 90 deg. Most common for classic retrofitters is a rear head with #6 & #8 O-ring ports at the top. Might be able to get either "polarity". Sanden compressors are usually in the SD14 and SD15 body dimensions, and most brackets are made for that. Some use the SD13 "shorty" if they don't have clearance at the back. I think those are factory in a Honda Civic, so "should suffice" for an A-body. It's not like you are in the CA Central Valley (we hit record 47 C last September). I haven't seen a Sanden mounted below the alternator (right side) in either a slant-six or small-block V-8. Probably not enough room at the rear to the block. Most brackets set it above the intake manifold in V-8 or on the left side for a slant-six. See Bouchillon Performance Engineering for V-8 brackets. Don't know if you can still buy the slant-six brackets that a few vendors show. See that thread for info.
 
This is for my 70 Charger so more space ;)
are there any "special" tricks etc. that sets apart a great system from a regular system? E.g. in regards to maintenance, durability, performance?
would it make sense to have low and high pressure ports?
 
The main efficiency comes from having a larger condenser and parallel-flow is 30% more efficient for the same size. Duracool claims their "Oil Chill" is more efficient since stays in the compressor better. I think that is Hella PAO 68 which is the best oil - doesn't absorb moisture to form acids like PAG and compatible with all refrigerants. You must have a low-pressure port to be able to fill. A high-pressure port is nice for ideal monitoring, though the low port is good enough to tell if a proper refrigerant charge (should be 30-50 psig on 70 F day after sitting long). I put a small pressure relief valve in the outlet of one of my Sandens, which will vent if >300 psig. That may keep the compressor from stalling on a very hot day (108 F) to burn-up the clutch, which happened in two of my cars (OEM compressor), but you won't see such days unless you drive to Anatolia (49 C record in 2021). Illegal to vent per U.S. EPA, but w/ HC no worries.
 
Btw how do you charge a system like mine? By refrigerant weight? By pressure?
 
I've always started with 1 can for a dry system (add oil to compressor first, measure it), whether R-12, R-134A, or Duracool. That gives some cooling, but usually see ~25 psig low-side w/ compressor running on an 80 F day. I then add another full can, stopping before I read 50 psig, though usually hits ~40 psig which is perfect. R-134A cans in CA have a spring-loaded output valve, requiring a special adapter. That is so you don't vent any excess the atmosphere. You return the can for a $10 refund and the parts store sends it off to recover any excess refrigerant left in the can.

Once I added Duracool but still had left over, so did an experiment. Web geniuses claim it is "explosive", so I poured some liquid on the cement and lit it. No explosion, it just burned slowly like a candle flame. It can only burn as fast as it vaporizes (also true for candle wax). I even blew it out and let my little girl have fun lighting the "water". Didn't surprise me since, unlike these web geniuses, I took two graduate engineering courses in combustion. Indeed, you'd swear the 6 oz can is empty (compared to 12 oz R-134A can). You should be more afraid to carry a newspaper in the cabin. If it does leak, you know it from that sulfurous "natural gas" smell (mercapton added). How common is a refrigerant leak into the cabin anyway? Duracool paid for an engineering study that calculated even if the full charge instantly leaked into the cabin, it wouldn't form a combustible mixture with the air inside.
 
I now almost feel comfortable to tackle this project on my own! Did I forget anything?
Btw. Is there an advantage for using hard lines where possible (despite having more connections)?
 
Hardlines are smaller and lighter, especially if aluminum. You can't bend aluminum tubing much without cracking. I have only used them when part of OE design or short sections when connecting to something like a condenser which has special "peanut" fittings for which a hardline w/ fitting is all you can get.
 
A few years ago I had to replace the heater cores in both of my Dakotas within a few months of each other. You know the old, "replace everything while you're in there" thing.....
Well I didn't care about the AC on the 92 as the compressor was shot anyway.... It was basically an idler for the serpentine belt was all by now.
So I didn't worry about the evaporator on the 92.

When it came time to do the heater core on the 96 well it was in nicer shape overall and alot less miles at the time, so yeah I figured I'd do the evaporator on this one. What a mistake. On this one they showed 2 choices of evaporator. A parallel and a serpentine type.
I tried to research the difference (I was ordering part and didn't have it apart yet) to see what kind it had in there already (remember I couldn't see thru the firewall haha) and didn't know the difference.
I don't remember the price difference at the time but I believe the serpentine was more expensive.
So I googled all over to see what the difference might be, somehow I decided to try the serpentine one. What a mistake. It didn't fit the plenum right, to begin with. Had to cobble to keep it from dangling around. Then I couldn't get the drier to attach no matter what I tried. The 96 had the round style with the garter spring that takes the "disconnect tool" to release. The 92 which was still originally an r12 system, had flat flanges with shim-thickness metal gaskets. The 96 was r134 from the start. I never did get to charge the ac in that one and I wasn't taking the dash apart to re replace the evaporator, and wasn't about to pull the dash apart to redo the evaporator. So it's stayed un charged ever since.
That truck has seen better days, body is quickly falling apart, paint has peeled long ago, has 1/4 million miles on it, and has been basically demoted to my "mowing truck" in the warm months and my winter "beater with a heater" because of its 4wd and my 70 mile a day commute.
 
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