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kung fu jesus
05-27-2012, 11:48 AM
I'm starting a project to reinstall my aircon into my Miata. I originally had it in the car, but removed it about 5 years ago. I kept all the parts and left the electronics in the car. I am going to try to document this and will edit the posts with pictures as I have them.

That system had been converted to r134a when I lived in Charlotte.

Removing it is something I have regretted.

Anyways, I bought a complete system used from a '97 about a year ago with the intention of installing it in my car. Physically, the two systems are similar. The 94-97 systems came from the factory with r134 as the refrigerant, previous years was r12. r134a, according to the info I have read is about 80% as efficient as the r12, but is still very effective and less harmful to the environment.

Moving from California back to NC has moved this project up as a priority. I will also use it to diagnose and gain some practice so I I can fix the AC on my wife's '99.

Another difference I found between the NA6 and the NA8 is in the wiring. Fortunately, since my car already has it in place, I won't need to lay in the harness. The NA6 uses one relay to control the clutch on the compressor and also to turn on the condenser fan. On then NA8, there are two separate relays; one for the compressor, one for the fan. The pressure switch is also different between the NA6 and the NA8. Fortunately, I just tested the mounting ports and the NA6 switch will fit on the NA8's line.

(insert picture here)

Right now, all I am doing is surveying my inventory: what I have, what I need, re-familiarizing myself with where the lines go, how they attach to the chassis, etc.

I have been looking up parts online to see what crosses over between the two systems. Although I have the complete systems, there is stuff I plan to replace just because "I'm in there". Fortunately for me, too, the previous owner of the NA8 system sealed all the orifices and openings as he removed it. The compressors are a little different because of the refrigerants. The driers are different, the condensers are the same, the expansion valves are the same, the evaporators are the same, the pressure switches are different, the o-rings and seals are the same. I haven't looked at the hoses (the flexible ones), but I am not planning to replace those.

Right now, I am planning on replacing all the system's o-rings, seals, dryer, expansion valve, and pressure switch. Altogether, it's about $100 in parts. I will use the NA8's aluminum lines with the NA6's pressure switch. I will use the NA8's evaporator because is 5 years newer and has been sealed. I left my evaporator open to the engine bay and I'm sure 5 years of dirt, dust and crud has ruined it. I think swapping them out won't be too difficult.

In the meantime, while I order parts and assess the install, here's is good OE installation walk through:

http://homepage.mac.com/akerman/misc/90ACINST.pdf

kung fu jesus
05-30-2012, 10:53 AM
Ok, ordered a pressure switch to fit the '92 electronics. Also ordered an o-ring and gasket set for a '97, though it appears the same kit is applicable from 90-05. Also ordered an accumulator/drier for a '97. The Drier is cheap and should be replaced anyways.

Parts should be here in a few days. I will get some compressor oil locally for installing the rings and also to change the oil in the compressor.

I am a little tardy taking pics of the hardware so far. I will try to get them soon.

friday
05-30-2012, 01:57 PM
A/C repair is one of the car things I really don't enjoy, it can be so fidgety. Do you have access to a machine that can recycle and vacuum the system down properly?


I take it the east coast humidity has inspired you to get to work?

kung fu jesus
05-30-2012, 05:07 PM
I don't have the manifold or vacuum, I plan to have that done. Yes, the humidity made it a little urgent. I agree, it is fidgety work, but it is also pretty straight forward on these cars.

I took my wife's NB to a shop and was told it held vacuum, it was recharged with dye added and works now. So, at least we have one car with working AC. :)

Removing my AC is something I shouldn't have done, in hindsight. As much daily-driving I did in it, it would have been nice to have during the long summers in LA where 100+ temps aren't uncommon.

jnshk
06-01-2012, 07:29 AM
Some food for thought if you haven't considered it yet, but if you are using r134a and the NA8 compressor, I would think that the r134a NA8 pressure switch would be a more appropriate choice. I don't have the specs on either of them so they may be nearly identical, but sometimes even a small shift in cycling behavior can dramatically affect the efficiency of the system. I'm also not sure how much (if any) the ECM plays into the control of A/C in these cars, fwiw.

kung fu jesus
06-01-2012, 08:19 AM
I thought about that. The pressure switches are a little different. I went with the '92 switch because of the compatibility with the lines and harness. I wasn't sure what voltage the ECU would expect to see from the later models.

kung fu jesus
06-03-2012, 09:31 AM
Small update. I am waiting for the parts to arrive.

I took the '97 evaporator core and washed it out with some really hot water, dishsoap and a little bleach. I let it soak for a while, then gently scrubbed it with a bottle brush. The bleach is used in the soak to kill any mold or mildew that was in the fins. It's pretty common for it to grow there and gives you the "musty, moldy" smell when you crank up the blower.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0681.jpg
http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0682.jpg

It was pretty clean, but still had some dirt and grunge that washed out of the fins. Note the ends are capped off with aluminum tape.

moerdogg
06-03-2012, 10:55 AM
What does it take to "convert" a system from R12 to R134a? My 92's air still blows cold, but I imagine someday it won't any more. I don't use it much up here in NE, but those days when we're heading to the beach and traffic is dead stopped, it sure is nice to have!

kung fu jesus
06-03-2012, 02:36 PM
I am not an expert on this, but there are a couple ways to do it.

GOOD kits will have uprated schrader valves that connect to the existing valves on the high and low side. From there, A shop will evacuate the r12 in there (assuming there is any left). They will add a compatible oil and the correct amount of r134.

That is the short version of the story.

I have read different accounts of r12 still being available, but at a much more expensive rate. A lot of people don't know that when a shop evacuates your refrigerant, they can reuse it. Most places won't credit you for it.

Ideally, when you convert you should change the accumulator/drier. That is the canister-looking thing on the passenger side of the engine compartment under the upper radiator support. They are pretty cheap, $10-25. Why? r12 and r134 aren't compatible with each other. On a molecular level, the r134 is MUCH smaller than r12. They use different oils. The r12, as I remember, uses a mineral-based oil, the r134 uses something else. Also, if the system leaks and loses it's seal...the moisture in the air reacts with the chemicals (not radioactive) that start to eat away at the drier from the inside out.

Those recharging kits you see at auto stores are really a waste of money. The proper way to recharge your system is to evacuate it, create a vaccum in it, and monitor it with a set of manifold gauges to see if it holds the vacuum. If it doesn't, you can enter a dye in into the system and look for leaks. There are also chemicals you can use that seal the leaks, but there are varying stories on whether they work or not, based on how they seal. Some system sealants use oils to moisten the o rings, making them swell. Most refrigerant techs seem to agree this is an OK sealant to use. Another type is a chemical that when it reacts with the moisture in the air, hardens and seals the leak. You can sort of guess what can happen if you use that and you haven't evacuated the air and moisture out of the system.

I am trying to use generalities because I not am expert in these things, I am sort of paraphrasing what I have read. A good number of AC related threads on M.N have a member who is a certified HVAC technician/repairman who explains a LOT of these issues in really good detail.

The amount of r134 you would use in a converted system is different than you would use versus r12. The amount and type of oil used by the compressor(as mentioned earlier) is different, too.

I know a lot of people treat the HVAC on their cars like it's voodoo. It's not. It is typically an electrical issue or a hardware issue. If you understand how refrigerant systems work, it's easy to extrapolate and diagnose. Likewise, the electrical systems are pretty easy to diagnose. The electronics are setup in a way to save the entire system if there isn't in spec. It is a system of simple electronic switches and relays. I used the workshop manual on my wife's 99 to diagnose the electronics were good, so I knew if the shop I took it to for a charge said otherwise, I would go someplace else. I was actually surprised how easy it was to diagnose. I just needed a multimeter and a 3" piece of wire as a jumper.

When I took the NB to the ship last week, they pulled the vacuum on it and used dye. Not only did it hold, but no leaks were found. It held the recommended vacuum for 40 minutes without change. I can only suspect that the previous owner might have removed the system because he used the car primarily as an autocross/weekend toy. Anyways, it is recharged and works fantastic!

Usually, when a system leaks, the culprit is one of two things: bad o rings or a hole on the system. The entire oring kit is $10-15 and is just labor and a slightly delicate touch to repair. The other cause is a hole in the condensor (the AC's radiator) from a rock or debris. The flexible lines that run on the bottom of the car off the compressor can also crack with age or from debris, too.

moerdogg
06-03-2012, 04:59 PM
Thanks for the detailed reply! Agree that most folks treat the system like magic, that will kill you if you look at it wrong. I certainly don't want to be accidentally releasing CFCs into the atmosphere, but if the system is leaking the damage is probably already done. Hopefully I don't need to worry about it for a while yet!

kung fu jesus
06-04-2012, 01:49 PM
Update: I ordered a substance called RT201B Nylog Blue.
http://www.trutechtools.com/thumbnail.asp?file=assets/images/nylog_blue_thumbnail.jpg&maxx=150&maxy=150
It is lubricant/thread sealant for AC/refrigerant systems. It is specifically used on the orings, seals and fittings. It isn't something you can pick up at a hardware store, unfortunately. I bought a bottle for $6 + $11 shipping. :| It came highly recommended for improving the seal and life of the o rings and connectors on the AC system, so, well, OK.

BTW, there two types; red and blue. Red is a mineral oil-based lube/sealant for r12, blue is for 134a and other types.

I found it here:
http://www.trutechtools.com/search.asp?keyword=RT201B+Nylog+Blue&search=Go

A neat video about it here:


http://www.youtube.com/watch?v=vAULfI8-Wwk&feature=pyv&ad=4389036595&kw=nylog

kung fu jesus
06-04-2012, 02:06 PM
Here is the new pressure switch for the 90-93:
http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/Untitled.jpg

Interestingly, it has the data printed on it:

p/n YL-2139A
HP(high pressure) - 27kg/cm²
LP(low pressure) - 2kg/cm²

384psi to 28psi (!!!)

thedguy
06-04-2012, 05:15 PM
I've been looking at doing something similar to my e30. Something you might look into is finding a "parallel flow" condenser.
They are built to work with the smaller r134 molecules and improve the temperature reduction of the system.

Iirc the e30 guys that have gone this route song with the factory r134 conversion parts notice about 10°F improvement over the r12 condenser.

As always, you're are skill of useful info. Already missing you down this way.

kung fu jesus
06-05-2012, 10:39 PM
Thanks, man! That is a good idea!

I already have a good condenser, but if it wasn't I would definitely look into it! The prices are comparable to the bar/fin types.

For those following along, here is an interesting cutaway showing the differences:

http://www.ackits.com/parallel/condenser1.jpg

kung fu jesus
06-07-2012, 08:00 PM
OK, started getting the parts ready to upgrade the o rings. I started small, beginning with the capillary tube off the evaporator valve on the, well, evaporator.

The Nylog came yesterday. I have been enjoying shouting "NYLOG!" at the dog. She couldn't care less.

Here are some pics:

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0684.jpg
this is the capillary tube. It's the smallest fitting, and the easiest, probably.


You can see the tiny, black o ring on the copper thing to the left side. It wasn't in bad shape! There was oil on it and it was still pliable, not smashed and dried out. I am doing the o rings and nylog as a precaution. the rings are cheap so might as well do them...

Time to find the matching size preplacement o ring:

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0688.jpg



Put the new ring on:
http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0690.jpg


Adding Nylog to the fittings (both sides) and the ring:
http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0693.jpg

aaaand I reinstalled the fitting. These fittings don't need a lot of torque. The factory service manual (in the link at the bottom of the first post above) lists the torque settings. The Nylog is like stretchy snot, but easy to clean up. I am applying it as shown in the video I linked above. I am being a bit liberal with it, since it can't clog the system.

One o ring down, many, many more to come!

kung fu jesus
06-09-2012, 05:23 PM
I installed the system today! Pictures are coming. It took me about 5 hours doing it solo. Everything lined up great. The hardest part was hanging the compressor. It was a tight squeeze through the bottom of the engine bay, but I figured it out. :)

kung fu jesus
06-09-2012, 07:09 PM
OK, let's wrap this up.

When I installed this '97 system into my '92, I read the FSM installation directions a few times (linked above). It may be helpful to Google image search various engine bays shots for reference, too. Installing it is easier if you break it down into four sub-systems to install and tie together. Given that my AC electronics were still in place, I didn't have to worry about it until last to make sure everything worked.

Those four sub systems make it easier to tackle and install. They are: the evaporator assembly (behind the glove box), the condensor and drier assembly, the compressor, and the high and low lines that run along the passenger side of the engine bay. I am going to try to descrive what I did in each of those systems, in the order I did it based off the FSM instructions.

The Evaporator

Probably the most daunting of the install. I wasn't quite sure how this was going to play out because it is the least accessible part of the AC. In the posts above, I describe prepping the evaporator assembly and installing new o rings on it. I read a few posts on other websites and when all was said and done, it wasn't so hard!

There are key steps to getting it out, but first begin by removing the firewall grommets the tubes coming off the evaporator protect. Grab them with a pair of needle nose pliers and pull them away from the firewall from the engine bay side. Put them aside, you will be re-installing them later.

Next, remove the glovebox. There are four screws here. Two attach the glovebox to a strip of stamped metal, the other two remove that strip. If you don't remove the strip, you won't get the evaporator in or out. I had to remove my old evaporator assembly first.

There are two 10mm nuts that hold the evaporator box to the car. Remove those. Pull out the drain hose on the bottom of the box. It drains the condensation out a port in the floor. After that you will see a band on each side of the box. They have little mason jar-like latches on them, don't bother messing with the latches.
http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0716.jpg
These bands merely act like loose stop-gaps to keep the air moving to the rest of the ventilation system. They don't really seal anything. Slide the one on the right farther to the right and it should expose the end of the port on the box. Now pull the box away from the firewall off it's mounting studs. The box should drop down. If it doesn't, try pushing it to the right to remove the left port from the vent system.

One the box is free there are two wires clipped to the box. Use some needle nose pliers to grab them and remove them from the box. Take note or take a picture of which wire clips where.
http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0710.jpg

The box is free!
http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0715.jpg


Take the box/evap assy outside. There are a number of spring clips that hold the two side of the box together. Use a flat screwdriver to pry them off. Be careful, they may shoot away. I launched one about 12 feet away,out the garage. Put your other hand over the clips as you pry them off to prevent that from happening to you.

This is where it gets interesting. Carefully separate the two halves of the box. The evaporator in inside, encased in an insulating styrofoam shell. GENTLY separate the styrofoam shell. If it breaks or cracks, don't worry, you can use some duct tape to patch it up.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0712.jpg

Remove the evaporator assembly. There will be some interesting grunge, dead bugs, leaves and other debris in here.

Now, comparing the two evap assys I had (92 and 97), I couldn't discern any difference between them. You could re-ring your old one, clean it, maybe replace the evaporator valve if you are so inclined, and reinstall it.

Take not of the little plastic piece that locates the tubes that come out the box and through the firewall. There is also a small passage for the capillary tube. Clean everything thoroughly and gently. It will be pretty dirty.

Reassemble the box and install it back into it's location behind the glovebox. Install the two 10mm nuts loosely to hold the box in place. I used a flat screwdriver to slide the bands over the ports in box. The ports have little ribs that show you where the bands should stop. Reconnect the two wire clips to the box and reinstall the drain hose. Replace the stamped strip that hold the glovebox, then the glovebox itself. Go around to the engine bay and replace the firewall grommets.

That's it!

kung fu jesus
06-09-2012, 07:42 PM
The Condenser/Drier Assy

You can do this step next or the compressor assy, it's up to you.

I replaced the drier before installing this assembly. It's easy to do at this point and most pros will recommend you do it anyway. It's $15 at the most brand new.

Something I should have mentioned earlier; there are a lot of soft metals in the AC system (aluminum, copper, brass), they are easy to bend so use some tactful force when you work on these parts. A lot of the parts also have REALLY sharp edges, like the fins on the evaporator and condenser, so wear cloth gloves to save your hands. Some of the working spaces are tight and simply brushing your hands on them may cut them.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0698.jpg

Onto the drier! Loosen the fittings on either side of the drier. Every AC fitting has two sides. USE A WRENCH ON BOTH SIDE AT THE SAME TIME WHEN LOOSENING OR TIGHTENING THESE. You can bend, crush, tear the tubing if you don't. The tube may bend a little in during this, but you can easily bend them back CAREFULLY. If the tube collapses, it's no good and you need to replace it.

Remove the two 10mm bolts that attach the drier to the condenser. Finish removing the fittings you loosened previously.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0697.jpg

The new drier might come with new o rings. If not remove the old o rings and lay it next to your assortment to find the right one.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0699.jpg

If you aren't sure, lay them side by side. The new ring should be a little snug, needing a little force to slide it on. If it drops on, it may be too big. If the o ring twists while sliding it on, it may be too small. Don't let the o ring twist up while sliding it on. Always lube the new rings with AC compressor oil or Nylog before reinstalling.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0701.jpg

Bolt the new drier to the condensor with the two 10mm bolts. Reinstall the fitting on both sides of the drier. No need to go Hulk-smash tight on these fittings! Refer to the FSM link for torque settings to get an idea of how much to tighten them.

OK! The assembly is ready to install at this point. It may be a good time to straighten any bent fins in the condenser at this point. Inspect both sides and gently straighten any flattened fins with a pick tool or small, flat electronics screwdriver.

Lift up the front of the car, like you would to do the front brakes or something, use jackstands.

You will have to remove the air diverter first. It's 6 bolts, IIRC. It's the black plastic piece between the front bumper and the radiator. Place it aside and work the condensor/drier assy up from the bottom. the top of the dryer will be on the passenger side, facing the front of the car, just under the upper radiator support. There are four mounting tabs on the condensor that correspond to mounts in front of the radiator. On the driver side, there is one stud in place. This is helpful to line up the condenser. Use 3 10mm blots (about 16mm long) to attach the condensor at the other three points. The upper mount on the passenger side is a royal bitch. Removing the bumper tilting the radiator will help. It will take some patience. The other three are pretty easy. Good to wear your gloves while doing this part!

From underneath, look up into the mall space between the condensor and the radiator. Make sure the gap is consistent and the two aren't touching! They will rub through one another pretty quickly if they are.

With the condenser/drier in place you can now move to the next sub assembly...

kung fu jesus
06-09-2012, 08:11 PM
The Compressor Assembly

Completing this portion took more out of me than the others. The weight of the compressor and the flexible lines attached to it make it a little awkward to maneuver into the engine bay. I have power steering, so the hydraulic lines made it a tighter fit. Because of that, I had to install it from the bottom.

If you have power steering, you want to slacken the tension on the belt and remove it. You will need a new belt that is compatible with your configuration. The old belt will also interfer with the installation of the compressor.

Next, there is a cast iron bracket that is needed to be installed to the side of the block. I would recommend prepping a few things first. Check to see if the holes for the bolts that attach the bracket need to be chased. You're dealing with iron here, so sometimes it can fill with rust and debris. Also, check the holes ON the bracket that the compressor mounts to. Test fit the bracket to the compressor. Start by installing the bracket with the four bolts. Don't forget to install the fifth, longer bolt that runs perpendicular.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0706.jpg

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0708.jpg

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0707.jpg

Here is the r134a and r12 compressors side by side. Not much difference except the tags on he back that list the refrigerant it is designed for.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0704.jpg

I had to remove one of the flexible lines to get the compressor up onto the bracket to install it. I was re-ringing these anyways, so no big deal. At this point you may want to drain the oil in the compressor and pour in new compressor oil compatible with r134a.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0705.jpg

I don't recall the exact amount, but it is only a few ounces. Any autoparts store will carry the oil.

Install the compressor to the bracket with the four, longer bolts. Reinstall the flex line mentioned above, if applicable.

The hardest part here is from "T-rexing" - big body, useless arms. Working from underneath, the blood drains out of your arms and you are left trying to handle the compressor which is about 10-12 pounds. They start 'rexing and you have to rest. :p

Connect the single electrical lead from the compressor to the connector found near the driver's side headlight. Zip tie the loose wire to the coolant hose it is near to prevent the compressor belt from catching it.

Install the new belt over the crank pulley, PS pump and compressor pulley and tension it.

Almost done!

kung fu jesus
06-09-2012, 08:27 PM
High/Low Lines

Time to install the high/low lines (h/l lines).

I had to remove the intake on my car to gain more room to install these. This is where some engine bay pics are handy to see how they run.

If you are installing a new pressure switch, this is the time to do it, before they are in the car.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0703.jpg

Start at the firewall, test fit the line at the bottom of the two from the evaporator. Lay it in for now. Do the same with the upper line.

http://i237.photobucket.com/albums/ff166/force_mccocken/AC%20repair/IMAG0717.jpg

My camera died on me at this point. Look under the car and take note of where everything connects to. You won't be able to misconnect them if you take a minute and look at the connections.

Remove the washer bottle for more access to the connections at the firewall.
Install the lines at the firewall. Re ring and lube.

LOOSELY attach the h/l lines to the brackets that connect them to the engine bay along the passenger side. There are two brackets, each has a single 10 mm bolt.

Get underneath the car and look at the connections to be made. The H/L lines overlap each other at places, so study the bends in them to make sure they are oriented correctly. When you feel confident they are correct, connect the H/L lines to the compressor flex lines and the condenser assy.

Connect the bracket that bridges the flex lines off the radiator, at one of the fan mounting bolts (10mm).

Check the hard lines thoroughly and make sure they dont interfere with each other. they should tough one another nor the car except at the mounting points. You may have to bend them gently to get them to clear.

Tighten the brackets down, reinstall the washer bottle, check to see if your fuel lines are interfering with the H/L lines. Use zipties to create clearance.

At this point, you are done! You can lower the car and reinstall the intake and anything else you may have removed.

I have a lot of o rings left over. I didn't disassemble the compressor and a few of the lines. I am confident they will be alright. Save the extras, they look compatible with fuel injectors and other items on the car.

kung fu jesus
06-09-2012, 08:37 PM
Checking the results...

Fire up the car and turn on the AC. Your car's idle should jump up a bit. Turn off the AC and the car. Your compressor clutch won't engage because there isn't any pressure in the system. The pulley will turn, but the forward end of the compressor won't. Don't worry, this is normal. It does this to protect itself. :)

Remove the connector from the pressure switch on the H/L lines. Jumper the connections on the harness side with a piece of wire. Start the car again. Go to the engine bay and look at the end of the compressor. It should be turning now. If it isn't, check your connector again, check the jumper. If that isn't it, you will need to diagnose the relay.

If you don't have a gauge manifold set and vacuum pump, take it to a service shop and have them evacuate the system, check for sustained vacuum and refill with refrigerant. If you didn't add oil to the compressor, tell them. Also, tell them you updated the AC system from a newer model. Give them the year it is from so they know how much oil and refrigerant to add.

Good luck!

kung fu jesus
06-12-2012, 12:45 PM
Success! Shop called back saying,"system is tight as a drum, blowing ice cubes.". :)

thedguy
06-13-2012, 03:17 PM
Lets get temp gauge on that, I"m curious the temp differential

kung fu jesus
06-13-2012, 06:54 PM
if I had one, sure. It feels colder than Tina's NB.

rsa
08-26-2012, 04:39 PM
Success! Shop called back saying,"system is tight as a drum, blowing ice cubes.". :) Cool! I just finished having a 1990 "de-converted" from R-134a back to R12.
In the meantime, while I order parts and assess the install, here's is good OE installation walk through:

http://homepage.mac.com/akerman/misc/90ACINST.pdfApple shut down mac.com, so that URL is dead. The new URL is http://webpages.charter.net/a7037196/miata/90ACINST.pdf (or you can use archive.org and the old URL).

SM16RMSM
08-26-2012, 06:06 PM
It won't be too much longer before R134a is the same price for R12. Good for you getting it done now than later.

I<3flippyheadlights
08-26-2012, 07:47 PM
Wow stumbled on this thread and it will help so much. I plan on keeping my old AC but it helps to have a written guide.

rsa
05-31-2020, 02:05 PM
Cool! I just finished having a 1990 "de-converted" from R-134a back to R12. Apple shut down mac.com, so that URL is dead. The new URL is http://webpages.charter.net/a7037196/miata/90ACINST.pdf (or you can use archive.org and the old URL).Charter shut down webpages, so that URL is dead. The new URL is https://www.dropbox.com/s/45si5ni8clfb8sz/90ACINST.pdf?dl=0