EastCoastMojo GRM+ Memberand Mod Squad
4/11/14 3:39 p.m.

OK, so I've done enough googling on this subject to thoroughly confuse myself. I am getting different info on whether I have an R12 system, and whether I should convert it to 134a or not. Here is a pic of the fitting on my system:

Last year when I bought the truck (1993 Mazda B2200 carb'd) the a/c worked OK, not stellar but it was the end of the season so it was good enough. Now that it is getting warm I find that the compressor does not kick on at all. The spinny thing on the front of the compressor does not move when the a/c button is engaged on the dash. I have checked the ac fuse and it is fine. Here's where it gets fun - I think this truck uses R12, based on the opinion of the guy at the local parts store that I trust.

Now, looking on the internets I find that there are differing opinions (surprise) as to whether you can upgrade to 134a without changing parts. I always ASSumed that the conversion would require at least a rebuild of the compressor to replace o-rings, and of course that sounds like a huge pain in the ass so I would guess that is probably the case here. Is it possible to just recharge it with R12 or is that stuff unobtainium nowadays? I didn't want to take up the parts store guy's whole day with my a/c ignorance. I know the right thing to do is find the leak first, and I will have to call on the assistance of someone who has the equipment to do that, as alas I don't have a UV light nor any cool ass yellow glasses.

What say you guys on the whole conversion? Should I keep it R12, which by what I'm reading provides better overall cooling that the 134a and has the potential to be cheaper? Or should I start saving my scrillas for a 134a upgrade, and if this is the answer, what can I expect to spend to convert it? I know I don't have the tools and know-how to do this myself, but I want to get my brain wrapped around it some before throwing money at it.

Thanks as always for your advice gang!

JThw8 PowerDork
4/11/14 3:52 p.m.

The internet is full of "you can't do that" I've "converted" plenty of R12 systems by draining them slapping on the adapter fittings and filling the system with 134a. Worked fine, didn't destroy my compressor or anything else.

You'll be hard pressed to find R12 even if you want to and it will be 10x the cost of just putting the R134 in there. Its true the R134 wont get as cold as the R12 but it gets cold enough.

aircooled UltimaDork
4/11/14 3:52 p.m.

You don't have to spend the big bucks for R12 (although I do believe the price has dropped since the demand is dropping) you can just add one of the blend replacement (e.g. Freeze 12, Envirosafe etc).

You system MAY just be low on charge. You can hit one of the ports with a stick or something and see if there is any pressure (be careful of course). If there is not pressure, you will need to evacuate. If there is some pressure, recharge it with some leak sealer charge.

If your compressor is dead, you will need to open the system anyway, and should replace the accumulator. In that case, replacing the o-rings in not a huge deal, so 124 seems reasonable. They SAY you have to replace all the hoses with barrier hose, but apparently if they are old, the oil from the R-12 charge tends to seal them up.

If you are rebuilding the system anyway, certainly go with R-134, but if you are just recharging, a replacement is probably the most cost effective.

I have a B2000 with AC that I have been keeping alive for many years with Envirosafe. Some of the R12 had leaked out and the replacement has a leak stopper in it, so it eventually sealed up.

Not a super expert here, so others may have slightly different opinions.

oldopelguy SuperDork
4/11/14 4:07 p.m.

Screw on fittings indicate it was originally an r12 system vice the quick connect fittings used for the newer stuff. Usually in the conversion adapter fittings are installed and left in place, so odds are it has not been converted.

Conversion could be as simple as squirting in a can of stuff that supposedly stabilizes the oil and seals the system to keep the new gas from leaking out. Several very informed people will prove that it shouldn't work and others (like me) have done it with varying success.

More correctly, all the seals should be replaced, oil purged and replaced, new orifice or expansion valve installed, new dryer, and maybe new lines made out of different materials installed. Vacuum out the air, charge it up and go.

If your compressor is like most than a reman for the new gas is cheaper than the gasket kit to swap over what you have. Converting to the new gas you will buy a new dryer anyway, so adding the magic gas would at worst blow up what you would be throwing away anyway to convert properly. Best case it works some for a while and you gather up the parts.

Obviously if you have a good, expensive compressor than it would be worth some caution. First step is that research.

There are also some other gas options, like freeze 12 and the like, that are generally not approved but may work fine. I have used freeze 12 mixed with R12 and it did work, but I didn't keep the truck long enough to comment on longevity.

ddavidv PowerDork
4/12/14 5:38 a.m.

I converted my Audi GT to R134a when I modernized it with a Sanden compressor vs the old York style (still R12 components). The only parts I replaced were O-rings and hoses, because I needed custom fittings to route the latter. The system worked BETTER than it had with R12. What I did learn in speaking to several a/c techs is getting the pressure just right is a little fussier with R134a, but if done correctly, will get the results I did. I too read endless pages saying "You can't do that" but proved them all wrong.

Knurled PowerDork
4/12/14 2:43 p.m.
JThw8 wrote: The internet is full of "you can't do that" I've "converted" plenty of R12 systems by draining them slapping on the adapter fittings and filling the system with 134a. Worked fine, didn't destroy my compressor or anything else.

The hysteria over conversions (you will leak refigerant from every hose and O-ring and the compressor will explode and your dead grandmother will crawl up your knees with a knife in her mouth) from ten-fifteen years ago reminds me of the hysteria over E10 today. I wonder what planet they're on, because on the one where I'm living, none of that stuff is happening.

When I was actively doing refrigerant conversions, as a company policy, we just did a normal evacuate/vacuum/recharge like any other A/C service, except with the added steps of installing the adaptor fittings and the correct amount of PAG oil. 85% of the R-12 charge was what we used for the R-134a charge. The R-12's oil would just collect in the accumulator and sit there minding its own business. The world failed to end, component life was not measurably reduced, and 95% of the time the cars would still blow 35 degrees out the vents.

We don't do 'em anymore mainly because the switchover started in 1993 and everything was R-134a in 1994MY. We don't see anything that old anymore, and if we did, it was converted a very long time ago.

On the other hand, R-12 has not changed in price much since 2000. Still about $90/pound.

DeadSkunk SuperDork
4/12/14 3:38 p.m.

So.......I intend to one day get my 1991 GTI back on the road and it has an R12 system .I know it is still pressurized somewhat. Where would one go to get a conversion done if the R12 to R134A started twenty years ago? Are shops still available to do it?

Knurled PowerDork
4/12/14 4:05 p.m.

Depending on the shop, you might be able to get paid for the R-12 that they pull out. Well, paid for it against the service fees/R-134a cost.

The service port adaptors are still available.

lnlogauge New Reader
4/12/14 5:32 p.m.

freeze 12 on ebay is a pretty cheap source.

scratch that. good lord that got expensive.

JacktheRiffer New Reader
4/12/14 6:28 p.m.

My Z was just swapped over. Works fine and nothing is broken.

EastCoastMojo GRM+ Memberand Mod Squad
4/13/14 3:04 p.m.

Thanks for all the info! I am hopeful that I can get her going on the cheap. Easy is also a huge plus.

In reply to aircooled:

Is this the envirosafe kit you used? $35 bucks seems plenty reasonable to me.

I have not tested to see if there is pressure in the system yet, do I check that on the high pressure side? If I have some pressure, I would l think that I need to at least get enough pressure in there to see if the compressor kicks on at all, does this seem right?

aircooled UltimaDork
4/13/14 3:16 p.m.

You forgot the link, but I did buy a pack online.

Yes, the compressor will not kick on if the pressure is too low. Best to check the low side for pressure in general, but if the compressor hasn't been on it won't matter.

aircooled UltimaDork
4/13/14 3:19 p.m.

Of note, since we have almost the exact setup. It turned out that mine was leaking from the valve on the high side. Since replacing the valve core requires loosing all the pressure, I bought one of those 134 conversion kits to adapt the valves then just used the high side one to seal it up. It's been holding for a few years now.

EastCoastMojo GRM+ Memberand Mod Squad
4/13/14 3:20 p.m.

Oops, link added.

aircooled UltimaDork
4/13/14 3:27 p.m.

OK, I see it now. I just bought the cans and a old R12 guage set off of ebay. But that looks like a pretty complete kit. It looks like it uses the R134 fittings and included the adapters I mentioned above.

I should be perfect for what you need to do (assuming there is some pressure in the system)

Good luck. Hopefully it is either a very small leak (leak stop will get it) or a valve leak like mine and the adapters will take care of it. If it is a big leak, I would think the system would not have any pressure anyway.

EastCoastMojo GRM+ Memberand Mod Squad
4/13/14 4:17 p.m.

I just checked the system on the low pressure side, and I do still have some pressure in there. I think I'm going to order the enviro-safe kit and give it a go.

wlkelley3 SuperDork
4/13/14 7:35 p.m.
EastCoastMojo wrote: The spinny thing on the front of the compressor does not move when the a/c button is engaged on the dash.

This sounds like the clutch isn't working. They usually can be replaced without removing compressor but it's a big pain. Getting replacement clutch is also a huge pain nowadays. Usually easier to replace the compressor, unfortunately.
Silly I know but I have to ask, was the fan on when you engaged the A/C?

EastCoastMojo GRM+ Memberand Mod Squad
4/13/14 7:39 p.m.

In reply to wlkelley3:

Fan was set to high, a/c button on, temp set to full cold. Didn't kick on after a minute or so, but I didn't run it for too long. It did work last year, so I am hoping it's just low enough on charge that the compressor isn't engaging. I like that the kit I linked to has a stop leak component, fingers crossed that the compressor still works.

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