1966 AC system repair

[Broughj]

I am trying to get the AC and heat system in my 1966 convertible operational again. I have the engine and trans out now, so access is much easier. It is an ATC system that has not been upgraded. I have verified that all the vacuum servos and doors work properly when vacuum is applied. I've worked on the blower motor (see previous post) and have it working at least for now. Before I removed the control box, I verified that I had 12 volts to the compressor clutch wire, that the blower ran, but only at one speed, when a selection on the control panel was made and that there was no vacuum signal coming to the blend door actuator. I removed the control box and found it to be the 1966 part number that had not been upgraded. I did some diagnostics on the box and to no surprise it is bad. I've read as many posts as I could find explaining how to use the 1967/1968 parts to upgrade the ATC system so that it will work. I've started searching around to find what I need for the upgrade.

That said I'm seriously considering replacing the ATC system with a manual AC system. My thinking is that the manual system is less complicated and therefore probably more reliable over time. I really don't want to have to get under the dash down the road to replace another failed control box. I've not been able to find as much information about what is involved to convert the ATC to manual as the other way around. I know I need the manual control panel from a 66 or maybe a 67, the manual control box, and a blower resistor for the manual system. Do I need a wiring harness from a manual AC system? What else is needed? Does anyone have the manual AC system components that I need? I've looked on the usual suspects websites and have not found much. I've not talked with any of them yet. Any advice, suggestions or guidance is greatly appreciated.

Regards,
John

[LithiumCobalt]

Hi John,

I would advocate for fixing the ATC system as it really is superior to the manual system. Descriptions, part numbers and photos are in this thread: viewtopic.php?t=52481&hilit=66+69+ATC+retrofit

For all the work in converting to a manual system, you may as well upgrade the ATC as you will be replacing parts regardless. There is nothing mystical about the ATC. There are many that would like to shit on this system and it's not warranted. The 1966 system in original form, however, deserves criticism.

[frasern]

The last ATC box I sold worked for a short time then quit, I have two left, but after untold years of disuse, any used one is a gamble. The regular A/C box is the same as a heater box, only ATC is unique, and getting one rebuilt is a challenge. Finding the control head for regular A/C is getting hard.

[CaptainDave]

Send the ATC box to Florida and have it rebuilt, perhaps? Blair Farmer used to be the expert on those, probably still can help. Clearwater.

[TonyC]

Veering off the control side for a mite, my primary concern has been whether the bay components I have are compatible with the current stuff–which I don't really prefer, but am willing to accept just based on its availability, especially if all the new parts I have can take R-134. A few days ago I might have gotten a step closer to that. I went to a service shop to have a clog in Trigger's evaporator drain cleared out (which caused a flood in the passenger-side floor). While that was being done, on a hunch I asked the head tech for input regarding the decal on my receiver-dryer, which has been the main obstacle in my quest to put Frankenstein's A/C together and charged up. He said the desiccant indicated should work with the current stuff, but he suggested getting further input from another A/C outfit in town that really knew its stuff. After the drain was cleared, I went to the other shop, showed them the decal, and they said it should work with the current stuff. So, I've decided to take a chance with this dryer.

My next issue with this quest is to pull out the compressor and read up on any literature in the box regarding its compatibility. I'm not sure how PAG oil would work on a York design, or the right way to insert it. There must be a way, as some here have done the conversion without changing anything save for the receiver-dryer.

---Tony

[Broughj]

I don't have any experience with R-134 conversions. I cannot imagine that the York compressor would be a problem if the oil was changed. I think there is a drain plug on the bottom of it and a fill plug on the side somewhere. Sounds like you have a new or rebuilt compressor. I will need one as well since my original is seized. I just bought a new dryer from Old Air Products. It looks pretty much identical to the original, so should be an easy bolt in. No idea if it is suitable for R-134. I'm planning to keep my system R12 or one of the drop-in replacements.

[TonyC]

That was also my original intent, to keep R-12 or compatible refrigerant. But a shed fire 10 years ago destroyed my remaining stock of Duracool (as well as all the new A/C components I had collected to that point); and since our all-knowing/all-caring government subsequently chose to impose sanctions on Duracool shipping, that has cut off that option for me. My studies of dryer desiccants suggested that new dryers may be fitted with a desiccant that can work with either type–12 or 134a–of freon, but you have to confirm the type of desiccant used in yours first. There should be a decal on your dryer indicating what desiccant it holds.

Side note: Despite that aforementioned fire, I was able to start a new collection of A/C parts, and I now have everything I need to put that system together save for refrigerant. Except for the clutch pulley and service valves, which have all been inspected and cleaned up, everything is brand-new and still in their respective boxes, still as yet not exposed to any freon of any kind. The only new part that is in place in the car is the evaporator core, which I had to do while the engine was out 3 years ago. But I left all the shipping plugs in place to make sure no foreign materials would get in there.

---Tony

[1Bad55Chevy]

The question is where do you get R-12 when it hasn't been used in 30 years?

Be careful of shops that say they have it in stock. If they don't show you the cylinder don't believe them. I have seen a good number of old school guys fill those systems with propane when R-12 started to dry up.

[LithiumCobalt]

Just had the system in my Mark III charged last month. The shop I use has ample supply. Now, the price is $90/lb, but whataya gonna do?

[1Bad55Chevy]

Just had the system in my Mark III charged last month. The shop
I use has ample supply. Now, the price is $90/lb, but whataya gonna do?

I really wonder if they filled it with actual R-12 or Duracool 12a. I don't know all the specs but I do know Duracool is some type of propane mix that is very expensive.

I don't even know if it would be unsafe to fill your AC system with propane. I understand it's flammable but so is 1234yf and that's what the auto industry is currently using today.

[TonyC]

Oh, if I could find somebody in the S.A. area that charged only $90 a pound, I'd already have put Frankenstein's A/C back together!! I only need 3-1/2 pounds, and I'd have no issues paying $315 for a full R-12 charge! I've been told the price was 10 times that amount, though, which got me to reconsider my freon options if the parts I already have allowed for options...which apparently they do, at least where the dryer is concerned.

[LithiumCobalt]

Oh, if I could find somebody in the S.A. area that charged only $90 a pound, I'd already have put Frankenstein's A/C back together!! I only need 3-1/2 pounds, and I'd have no issues paying $315 for a full R-12 charge! I've been told the price was 10 times that amount, though, which got me to reconsider my freon options if the parts I already have allowed for options...which apparently they do, at least where the dryer is concerned.

Might be worth a road trip to Fort Wayne, IN. They are top notch.

[1Bad55Chevy]

Oh, if I could find somebody in the S.A. area that charged only $90 a pound, I'd already have put Frankenstein's A/C back together!! I only need 3-1/2 pounds, and I'd have no issues paying $315 for a full R-12 charge! I've been told the price was 10 times that amount, though, which got me to reconsider my freon options if the parts I already have allowed for options...which apparently they do, at least where the dryer is concerned.

And this is why nobody fixes stock systems on classic cars. It ends up being cheaper/easier to convert to a vintage air system since R12 systems suck with 134a in them.

Why don't you just charge your system with Duracool or R290? Either of those refrigerant will take a little more then 1.5 lbs and you could do it yourself for a fraction of the cost.

[TonyC]

Oh, believe me, Chevy, I would use Duracool in a New-York minute if I could get it! It was easy to get 20 years ago, and that was what I used the last time I tried charging the system in 2009. I used half the supply I bought, but a hole in the evaporator core botched that attempt. I had hoped to try again with the other half once I eventually got a new or repaired evaporator core, but a shed fire 10 years ago cremated my remaining stock. I really wish now that I had thought of just putting that box in Frankenstein's trunk and kept it there while I did my time in Germany.
Plus, to add insult to injury, the government by then got wind of it and placed all sorts of restrictions and certification requirements to get any, just to flaunt their power. If I could make a secret arrangement with someone to smuggle some in from Canada, I would.

---Tony

[TonyC]

Might be worth a road trip to Fort Wayne, IN. They are top notch.

Maybe so...!

---Tony