Well I havent seen a whole lot of documentation on getting air conditioning working with a 3.8SC so I thought Id pass on what I did

Short and simple, get AC lines from an 87-88 4cyl, green and line washers from napa, and 2 10k resistors from radioshack to trick the ECM, and it will all go together in an hour or so

AC lines:
For starters you will need some "block line washers" or whatever they call them in your neck of the woods. They are thick metal washers with captured Orings. There is a Green one and a slightly thinner red one.
I found them at advanced for THIRTY DOLLARS a pair, or 3 bucks each at Napa.
So I went with napa. Part #407278 and 407297

Then for a straight bolt in find a set of AC lines from an 87 or 88 Fiero 4cyl only, not V6. They will bolt right in without modification. You MIGHT need to tweak just a HAIR. Mine just barely cleared the exaust manifold heat shield. Also because of how I mounted my engine they hit on the firewall slightly. A little pressure bent them out of the way.

Or get a set of V6 Fiero lines and a torch. The lines are aluminum and will bend very easily when heated. Trick is they also melt very easily, and you can break the welds twisting them. I was able to bend the first set and get them to fit.(which had a bad hose) then when I tried to bend the second good set, I broke a weld. You just have to be careful and take your time. You will need to bend them far enough to mount to swap the hoses by the time they get to the AC compressor. The Fiero compressor's high and low side are switched from the newer compressor. The 4cyl lines are already swapped so youd be better off just finding a set.

WIRING
Connect pin D of the C203 (light blue) to PCM Clear pin 22 dkgrn/wht. This is the AC demand wire. Check the exact diagrams for your year vehicle and engine, they probably vary.
Connect the AC relay just as normal
In the front there is a pressure cycling switch on the reciever/dryer. Unplug it and jumper the wires together. You dont need the switch anymore.
Now the only tricky part. Unless you want to hot wire the compressor, which is not a good idea, since the ECM will shut it off for you at WOT to save damaging it and free up power, we have to trick the ECM.
This is actualy easy. You need 2 10k resistors, color code brown black orange. Twist two ends together to make them into a chain. There are 3 wires to the AC pressure sensor, black (ground), grey (+5v), and red (signal). Connect the black to one end of the chain, the grey to the other, then the red in the middle where the 2 resistors connect. This will drop the voltage at the red wire to about 2.5V, or as the ECM sees, making it think there is 200psi on the high side. Right where it wants it. Make sure you soilder all connections and tape it up.

--ok this is where the simple answer ends and the complete guide starts--

THE ORIFICE TUBE (aka metering valve aka ...)
The orifice tube serves 2 purposes, 1 it limits the flow of freon on the high side, and 2 it catches particles of dirt. You want to replace it every time you open the system because its about $3 and can get clogged.
The orifice tube is located right under the brake booster, you will see a coupling in the smaller hose under the booster, unhook it and look into the passenger side hose, grab that little piece of plastic with some needle nose and pull, thats it.
IF its covered in black goo, you will need to flush the system, see below, otherwise, slide in the new one and go on.

THE RECIEVER DRYER (also has a couple of other names)
The reciever dryer is that canister thing in the front compartment. Amongst other things, the reciever dryer absorbs moisture from the AC system, so after so long it can no longer absorb more, this is why we replace it. Its about $45, and comes with new orings. You will need to drain it and measure the amount of oil that comes out. Now take your new pag oil and pour in that much, then add 3 more ounces to make up for the oil stuck in the absorbant. Just pour it right into the dryer. Then reinstall. I wouldnt bother replacing the sensor on it, you wont be using it.

THE ORINGS. You will want to pick up a box of R134A compatable orings. They must be 134A compatable, regular old orings will just fall apart after a week or so. They will probably be blue or green.
You will find orings to replace in the following areas
In front by the radiator 2 lines with couplers, take them apart and replace the orings
In rear where the AC lines hook from the engine to the frame
The reciever dryer (new orings should have come with it)
I think there are probably ones by the heater core, but Ive never taken that area apart to replace them
Basicaly just replace all the ones that you already have apart, plus the two by the radiator because they are easy to get to.
Before you install each oring, make sure the seat is clean, and wipe it with a little PAG oil.

THE COMPRESSOR
You should be using the compressor from the new engine. You should drain it and measure how much oil that comes out, then replace that with new PAG oil. If none comes out, check with the dealer to find out how much oil should be added to a new compressor on the donor car. I think the total system is like 8oz usualy. Other than oil, and orings/sealing washers which we already went over its set.
You are probably wondering why we do not use any of the cycling switches in the Fiero system, the newer compressors are variable displacement, so they do not cycle, they come on and stay on, when there is less demand, the displacement lowers so as not to over pressure the system, unlike the old cluctch slappers. The Compressor controls this internaly, the only pressure sensor it was designed to have was for the ECM to turn it off should the line pressure spike or drop below operating. So assuming you keep a good charge in it, and nothing goes wrong, you can just trick the ECM into thinking the pressure is ok, and the compressor will take care of the rest.

THE R134a conversion kit.
All you need is the $5 kit with the 2 fitting adapters,

EVACUATING
Before charging the system you will want to have a vacum pulled on it. Not to clean it out, but mainly to remove moisture. I forget the numbers but at x vacum water will boil at some tempature below common air tempature. So when they pull the vacum not only does it suck the humid air out, but it also boils and water in the system into the air. You will want to have a vacum held for about 30 minutes. Some people also view this as a way to check for leaks, yes any signifigant leaks will be detected, but also keep in mind -30ihg is far diffrent from 200PSI positive pressure, so you might miss something. If you've done everything Ive said you should be okay, as long as you dont have a leak in the evaporator or condensor, but you will usualy find those with a leakdown test. If you dont, and do start loosing freon, make sure your shop has a sniffer, then they will be able to pinpoint the location of the leak. UV light and dye is helpful also, but not as easy to detect if its a small leak.

CHARGING
If your Fiero is more than 5 years old, you should replace the reciever dryer and the orafice tube before charging. I was able to get both and 3 cans of freon at carquest for $72. DONT FORGET PAG OIL when shopping.
You will need 32oz of freon, when filling an R12 system with R134a you want to only use %80 of the amount of freon it calls for with R12.
Always get the adapter with a guage, its like 3$ more and could save your compressor or prevent a line blowout.
When shooting the coolant, keep a hot bucket of water handy, let the freon can sit in the water as you charge, otherwise it will get cold and freeze up inside not letting all the freon out.
After the first can you will want to start the car and turn on the AC. make sure the compressor is engaged, and crank the AC up all the way. Then continue to add the rest of the freon. Keep an eye on the guage, make sure it never goes above 45PSI (low side, which is where you're filling), but dont rely on the guage to know when its full, go by the 32ozs. If it exceedes 45psi, let it run for a bit and see if it comes down, try to get the full 32oz in but dont overfill.
If you've got the money to blow (and they will rip you a new one) take it to a shop so they can monitor the low and high side pressures while they charge. Thing is they will charge you about 7$ an oz if you are lucky, where as you can buy freon yourself for about 6$ a POUND.

FLUSHING THE SYSTEM
If your orafice tube is covered in black goo, or you suspect contamination, you should flush the system. I found AC system cleaner for $13 a quart at autozone.
Just take off the hoses however makes sense to you then dump some in. Theoreticaly all the goo would be in the oil which would be laying in the bottom of the lines, so letting it sit for about 10 minutes should disolve it, but I took it one step closer. I regulated the air compressor down low, the took off the other end of each line, blew some air into it to spread the cleaner, then set the air on low to make it "gargle" the cleaner to slosh it around. This was especialy helpful in the condenser and evaporator. Then high pressure air to blow it out. The cleaner is compatable with freon and PAG oil, so residue is not a concern. I would NOT flush the rubber lines that connect to the AC compressor, R134a molecules are smaller than R12 and can slip through the rubber lines designed for R12. Used lines have oil and R12 impregnated in them that block many of these microscopic holes, so flushing them would only open them up again.
Failure to properly clean a dirty system (especialy one that has the "black goo of death") will surely lead to quick compressor failure

Well I hope Ive given you the secrets to getting AC working on your L36 or L67 (or LQ1 for that matter) and properly educated you on general AC system maintance as well.

PLEASE correct me if I made a mistake, that way people dont mess something up because of my typo or mis-knowlege, but im confident in all I have told you.

The only thing I am not sure of is the proper PAG oil viscosity for the system, Im guessing 100, but ask your local dealer or ac shop what is right for the donor engine.

Oh, and a plus wouldnt hurt I missed mythbusters to type this up....


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If its not broke, you're not driving it hard enough. GO OR BLOW.

My car seems to prefer the latter, 6 engines, 2 trannys, 1 driveshaft and a whole lotta fun

[This message has been edited by 86GT3.4DOHC (edited 08-23-2006).]

Wow, that's a lot of knowledge for my tiny mind to absorb... very useful info. A nice synopsis - and the trick of using 4-cyl Fiero A/C lines sounds like a very cool discovery. Thanks for sharing this with us. You get a "+" from me.

EDIT: Oops, looks like I already gave you a "+"! Well, it's staying that way, for sure!

[This message has been edited by StuGood (edited 08-23-2006).]

Looking at the Fiero Store, they sell 4cyl a/c line for 84 and another for 86. Can we get confirmation on how many 4cyl lines there were and that only 87/88 lines will work with the L67 compressor? Much appreciated.

PICS! We need pics! I had custom lines made, but would love to see how this all fits together for "future possibilities."

Great write-up by the way! A + for ya.

Only the 87-88 ac lines will work

quote Originally posted by 86GT3.4DOHC: Only the 87-88 ac lines will work

If you bend the stock v6 lines as described, wouldn't they still have to mount inverted at the compressor? What is the integrated canister on these line called and is that HI/LO side specific?

[This message has been edited by ApexNC (edited 08-28-2006).]

For starters you will need some "block line washers" or whatever they call them in your neck of the woods. They are thick metal washers with captured Orings. There is a Green one and a slightly thinner red one.
I found them at advanced for THIRTY DOLLARS a pair, or 3 bucks each at Napa.
So I went with napa. Part #407278 and 407297

I buying this stuff today, just a note 407297 above, should read 407279.
According to a guide book at NAPA this pump should have PAG 150.
They did sell the washers as noted above for $3 ea. or a set with twice as many for $8.50, I went with that. I'm starting today and will try to take some pix as I go. I got a $16 Harbor Freight vacuum pump with r134a connector, hope it works. My biggest concern is getting the lines clean. That black goo is black mold and I'm told you don't want to touch it, let alone breath it.

[This message has been edited by ApexNC (edited 09-02-2006).]

Damn!!!!!!!!!!....Are you saying that you used the 87/88 AC lines on the newer 3800 pump? I paid a good penny to have my 86 Fiero lines joined the 3800sc lines. Im I reading you correct?

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" DRIVE IT LIKE YOU LOVE IT"

When I was mocking mine up yes, they basicly go right on with those spacers.

I'll post some pix in the next day or so, but this did not work for us and I have a hard time believing it will work for anyone. We are using 88 4cyl lines, acquired last week based on this thread. The lines are in great shape. These have the expansion chamber/"muffler" on both lines. With the recommended washers, the lines mated to the 02 GTP 3800 SCII easily. When mounting the compressor, it was obvious that it would require more than a "hair" of bending. We had to go from a 90* to a 45* (over and inch travel) to clear the firewall. With the compressor mounted and lines clearing the firewall, we now have too much hose. To angle the block to mate with the under car lines, will kink the low pressure hose. Irregardless of hose placement, there is no way to get the hoses to line up at the correct angle. I would have to heat and bend the two alum lines on the end to line up correctly. We fought this connection for an hour. I'd love to see some pix of this working, but I don't currently believe they exist. I think this was great in theory, but ultimately a lot of wasted time and money. Or perhaps I missed an alternative mounting possibility, please show me what I missed.

quote Originally posted by ohio86se: Damn!!!!!!!!!!....Are you saying that you used the 87/88 AC lines on the newer 3800 pump? I paid a good penny to have my 86 Fiero lines joined the 3800sc lines. Im I reading you correct?

but

I went this same route and had some made from the Fiero lines/3800 lines. It did cost a little more but the lines where made from new hoses and the exsiting ends. They fit like a glove and there was no extra bending or heating to get them to fit. Well worth the money and time saved from trying to make the Fiero lines work.

I think the reason why some ppl can get them to work and some cant is because of the type of exhaust manifolds ppl are using. On my 5 speed swap using WCF headers, the A/C lines had to be 3 inches longer than the set I used on my auto swap using the Togs.

Showing the compressor and hose assembly before install:


Zooming in to show the 45* bend near the expansion chamber/muffler (this was a 90^)


Looking straight up. You can see that even with the adjusted bend the muffler is still hard into the firewall. No issues with the stock exhaust manifolds here.


Dlightly different angle for what it's worth.


Close , but the lines have no where to go, there too long and kinked already to get this close.


The water hose isn't the issue here, it appears you could just push the compressor side of the aluminum ends up and change the angle, but there's extra rubber line already bunch up to get it to this point. The bend to this oint is ok, but then you'd have to bend the alum ends to mate the under car lines or disconnect and bend the under car lines to meet the hoses. Either way is beyond what we were expecting to do based on this thread. I'm sure the original poster can clarify how he managed this connection on his car.

[This message has been edited by ApexNC (edited 09-05-2006).]

Those are some very very very strange looking lines, mine look in no way similar to those. It seems that they are close, I would imagine some bending and you can get those lined up nicely. I have torn apart 2 fieros one 4cyl and one v6 and neither of them had the dual muffler lines like that, they also didnt have any fancy bends, everything is very simple on them, I will put a pic up when I get home from school.

BTW, 3.4dohc seems to go on breaks from PFF, he will be around eventually.

[This message has been edited by darkhorizon (edited 09-05-2006).]

Thx DH, are your 4 cyl hoses from an 87 or an 88? I look forward to the pic and any part # you find on the lines.
Mine are off an 88 4cyl. I thought they were interesting as well to have the two expansion chambers. I had asked for pix several times and several places as this is what I was afraid of. I now know the 88 4cyl could have the dual can or single can design, We'd need a part # or atleast a pic here to show people what they need. I'd still need to see what hoses supposedly work. Again, while these lines look painfully close; these "88 4CYL A/C HOSES" with dual cans WILL NOT WORK without major modification. For that matter you could say use A/C hoses from any car from any year and just bend the sh!t out of them. <-Sorry, that's the pain from the various cuts and lacerations obtained while trying to simply position the 88 4cyl lines into position talking. While I am currently grumpy about this experience, I'd still like to find out if perhaps "87 4cyl hoses" or "88 4cyl single can hoses" will work for this swap, both for my project and others wanting to do the same.
Does anyone know how significant the rubber line being "r134a compatible" really is?

[This message has been edited by ApexNC (edited 09-05-2006).]

The can near the compressor should be more of a 90* angle off the compressor I have used 88 lines on my 3.4DOHC and 87 lines on the 3.8SC (both have essentialy the same compressor) and as far as I can tell the 87 and 88 lines are identical, and I had no issues getting them to fit on either. I will say though it took some finangling to get them in there, they might be a hair long to be perfect, but I only had trouble getting them back into the clamp area, once I got them around the bracket they fit up ok. There might be a little bow in the rubber lines from too much length, but they dont come close to anything in that area.

As for the lines, when laying flat both ends should be parallel, as in the car, the compressor is parallel with the frame, and the lines are also, your lines it looks like with the compressor in square the lines are at a 90* angle to the frame, both hoses should end in a straight line, your short hose is a couple of inches too long and the hose is even bowed in the middle, it looks like you bent it out longer, I meant to just tweak the canister down twards the ground. Its literaly less than a half an inch. It will install just fine stock, but the canister will be pressed into the firewall insulation. It could be run like this, but I slipped a screwdriver in between and tweaked them down a little. I never got any pics as the change is so little you wouldnt know without holding 2 sets side by side, plus you cant even see anything in the car other than enough to know the lines are really there.

Your lines are way too long because you have added a couple of inches of length bending that line out , I would bend that canister back to closer to a 90* angle or until you get both lines the same length. You may need to tweak it down a little when you get it in the car (especialy since it has been bent from stock) but it will bolt in without bending, it will just touch the firewall. Once its in, just tweak it until you get suitable clearance.

Keep in mind you might run into diffrent issues if you mounted the engine signifigantly diffrently, mine is all but dead center and as low as you want it. Higher up the firewall tilts out so you might have 1/3" more clearance to make(or if you mounted it farther foward) , or if you mounted it far to the drivers side the lines will seem longer. With the 3.4DOHC I didnt even have to bend at all.

AFAIK all 87-88 4cyl hoses are identical, with double cans, at least the 3 sets Ive had are.

The problem with lines not being R134A compatable is the material is microscopicaly more porous. This means you might get a little leakage, but if you do not flush them, the fatter R12 molecules trapped in these pores will block it anyway, but even flushed theres not guarentee it will leak, and if so it will be immeasurable amounts. Its kind of like how an air filled ballon will deflate much slower than a helium, as helium is far smaller and slips through the pores.

What is the hose that is cable tied over the small hose? Is that just for rub protection? I would remove it if you didnt put it there, just to make sure someone wasnt trying to patch a hole, as that would not work.

Sorry if I have been absent lately Ive been real busy and just peek in from time to time.

86GT3.4DOHC, Do I understand correctly that the dual can lines are the ones you used successfully? So these are the preferred lines for this adaptation? A few points to follow up your last reply. We placed the additional hose protection there when we first received the lines, as we could see where the rubber was wearing on the canister. Obviously after the line adjustment, this is no longer an issue and we could now remove this added protection. The line is angled to this degree to avoid the firewall. This was the minimum angle to physically allow it to fit. To try to bend this tube upward or downward would have significantly increased the odds of damaging the line and the 2nd line would prevent downward direction and the exhaust prevents upward direction. Perhaps this all depends on the motor mounts and alignment on the cradle. I used Purple Reign made mounts all away around. As these lines won't be good for much else, I may try to re-bend them to take another go of it, but there appear to be enough variance here that it will not work for everyone. Has anyone else managed to make this work?

[This message has been edited by ApexNC (edited 09-05-2006).]