Getting stock AC working

[mkoecher]

I have a '76 F250 that came with stock AC and I'd like to get it working again. I dont know what condition it is in but I know that when I switch the AC is on the compressor engages but the air doesn't cool. I assume there was a leak and there is no refrigerant left. What is the best way of going about fixing the stock AC? Trying to find R12? Converting to R134a? Is there some kit out there to get the stock AC to work with R134a? Or are there other better options?

Thanks!

[sargentrs]

First concern is whether the evaporator core has a leak or not. If it's good, then I'd definitely swap to R134. Many will tell you that to do so you have to replace all your old condensor, drier, hoses, etc. However, I recently had an R134 swap done on a 1990 Toyota Camry, by an auto AC service center, and replaced nothing but the seals/o-rings and drained/evacuated the system thoroughly then refilled with R134. Blew cool and never had any issues. You can buy complete under dash kits, containing Sanden compressor, condensor, drier, hoses, etc for around $300. I've often thought about buying one, tossing the evap unit and refurbishing my OEM evap. There's some real AC "experts" on here and I'm sure someone will chime in with some more accurate information. In the meantime, check out this thread from a prior discussion... http://www.fordification.com/forum/view ... hp?t=73405

[1972hiboy]

Most a/c systems from 1989 onward are r134a retrofit friendly. It sounds like your a/c system is actually together and was working fairly recently. ( not like here in CA where most of these a/c's died in the 1980's and grandpa decided we didnt need to fix it becuase we live in CA ). That presents a problem all in its own. But I would say just find your leak and re-charge it with r12. simplest thing to do.

[mustang68 ranger71]

As I am sure you are already aware R12 is no longer available and 134A doesn't work very well do to the condenser being too small for the 134A. Well you can look this up on You Tube if you want and I am about to try this on my 71 Ranger. The aerosol compressed air like you clean your computer is no more than a type of refrigerant (R152 I believe) and from what I have saw it works great in those old R12 systems, better than 134A and in some cases better than the original R12. I would explain how to do it but their are many videos on You Tube about it. i am def going to try it in mine. Maybe someone here has done this. The only thing is it only takes one third the amount of 134 as it did R12, in most cases I have seen 2 cans is enough, and at less than $4 a can that's not a bad deal. Good Luck. Keep in mind you may have to add a couple ounces of oil.

[motzingg]

I don't know a whole lot about the hardware, etc from OG 'factory' air but most AC systems are pretty simple and consist of a few components.

First the compressor, if you've got a piston compressor, they are usually pretty bulletproof but after 50 years anything can happen. The biggest risk with these is running them out of oil. The 'york' style have an actual crankcase, so at the very least drain and fill the oil in there. If you need to rebuild it, its no more difficult to rebuild than an air compressor, piston rings, seals, gaskets and you're done.

R12 and R134 use different oil compounds, so you'll have to drain and refill with the R134 oil.

The o-rings and seals are also different, because of the chemical compounds R12 hoses and seals will degrade when you run R134 in them, so you'll have to replace the o-rings (mandatory) and should replace the hoses as most of the hoses will have degredation and pinhole leaks over 50 years. But you don't absolutely have to replace hoses, and if yours are holding, you might get away with it for a while before they turn into mush inside... given the amount of damage it can cause, i'd probably go ahead and replace them. A good AC shop can re-create the lines or crimp on new hoses to your old hardlines, or it might be cheaper to talk to vintage air or someone like that and just get all new lines.

Next after the compressor, it goes through a drier/filter which defnitely should get changed with the oil, as the oil will be saturated into it. They are pretty cheap.

Evap coil should be fine, but while you're in there replacing lines and stuff you can blow it out and get the dust and dead mice out of there so it doesn't smell like wet dong.

Then there is an unloading valve, right before the evaporator coil (inside the HVAC unit) these are supposed to be changed to a 134 spec unit, but i've run the 134 conversion before using the 12 unloading valve and it works just fine.

oh ****, i just realized i'm doing this backwards in terms of flow, ok, duh yeah... technically its going the other direction, but following with me, its going to be reverse... uh. yeah. ok sorry

but yeah the condenser coil is next, they are pretty much the same no matter what, thats the one in front of your radiator, since it flows from the pump into the condenser, the condenser accumulates all the nasty pump debris if your pump disintegrates, but usually that isn't a problem, i guess maybe flush the oil out with minearal spirits and blow it out with air and you should be good to go.

hook everything back up, suck it down with a vacuum pump (leave it hooked up overnight and make sure it holds vacuum before installing expensive refrigerant) suck in a can of oil and suck in the recommended amount of refrigerant.

Check that the pressure switch is working and check that the AC clutch works and you're back in business.

lots of people are intimidated by AC systems... i was before i moved to north carolina and gave a **** about it, hah! Its just a pump, two radiators and a valve, basically, its just expensive to make mistakes since the refrigerant is so expensive, and there is a ton of misinformation out there on line. Ever since AC first was installed the OEMs and aftermarket have tried to make it sound complicated so people wont mess with it, but its not rocket science. Just make really really sure you don't have any leaks when you put the juice in it and you're fine.

[68RGR]

There are quite a few people who think R-12 is unobtanium. That's just not so.

Sure, you can't run down to Walmart or AutoZone and get it off the shelf for 69 cents like you could 50 years ago.

But, I suspect there are hundreds of thousands of pounds of it in existence. Some of those are in garages and basements where the former owner has died or simply become disinterested. Others are simply forgotten - Waiting to be discovered. Others are for sale - Often at unreasonable prices. In the last 2 years, a local car dealer had over a hundred cans of it for sale - I thought about making an offer but didn't know what I would do with so much of it.

If you want R-12, check Craigslist or similar sources. I am aware of recent purchases where it was acquired for under $10 a pound. Yep, that's right, the same price as R-134a - Not the $25 and up prices some are asking for 12 ounce cans which is more like $33 a pound.

If you run across one of those "This is like gold" sellers, try this: Remind him that other options are available and that the demand has been dropping for years because the number of systems that need it has steadily declined. Plus, it is being recycled and that will allow for future supplies to be available. The suppliers of R-22, which is about to go the way of R-12, have been urging people to get their orders in because there may be no supply "soon" . . . And, that may be true for them because production of "virgin" R-22 is being phased out and their suppliers may no longer have it. HOWEVER, like R-12, and, possibly even more so, there are hundreds of thousands of pounds of it in existence. (30 pounds of R-22 was recently purchased for $85)

Neither one is unobtanium at this point and will not be in the foreseeable future, in my opinion. It might just turn out that, some day, you won't be able to give it away because no one will want it. (See: Betamax, 8-track tapes, 4 pound cell phones, etc that were all in great demand in the not too distant past.) In the mean time, it is available - You just have to look for it!

I used R-12 when I replaced a York compressor with a Sanden style a while back. R-12 works great - It is what these systems were designed to use. And, as long as it is available, I will continue to use it as appropriate. My goal is to have an ice-spitting system like the one that was in my 1969 Ranger years ago. And, I believe that R-12 just might be the only way to reproduce that performance. It really did "spit" ice pellets at the front seat center passenger! But, then, I never had to sit there . . .

To support the above:

Recent ad for $15 a pound:

http://okaloosa.craigslist.org/pts/5071512545.html

Older ads:

http://tuscaloosa.craigslist.org/mat/5045229019.html

http://bham.craigslist.org/pts/5018781356.html

These may or may not be available today as they have been up for a month or so. But, one seller is asking $17 a pound and that just might be negotiable given the ad has been up for a while.

The other is asking $17.50 a can and he might be negotiable as well.

On the other hand, this ad speaks for itself:

http://tuscaloosa.craigslist.org/mat/4981611535.html

[1972hiboy]

We still have shops in town that service R12 systems with thier machines and can still get it. Hell I personally have over 30lbs of it for " one day" projects.

[motzingg]

you can still get 'pellet spittin' performance from R134, it has more to do with the unloading valve and system operating pressure, than it does the working fluid.

true, r134 has a higher boiling point, but that just means your hot side pressure needs to go higher. ultimately the amount of cooling is governed by how much horsepower you throw at it. either fluid will perform equally well.

the whole r12/r22/r134 thing is just so DuPont can maintain their patents and force people to buy different refrigerants. basically all the same stuff, they just mess with it every time the patent expires and buy off some politicians to make the old stuff illegal.

[mkoecher]

Thanks for all the input. I am still debating between R12 and R134a. Does anybody have experience with R12a? Finally, one of my ac lines has a large swollen bulge in it so no matter what I decide to do it looks like I'll have to replace lines. I can't seem to find replacement lines from the auto store or from truck catalogs (LMC, Mac, NPD). How do I go about replacing ac lines? Does it require me to purchase one of those expensive ac line crimpers to make my own lines? Are there other options?

[guhfluh]

Classic Auto Air does a lot of original A/C parts refurbishment and I believe they also sell new parts that can still be found for original systems. Either way, call them and talk to them about your needs and concerns and I'm sure they can help. Their customer support is very good.