64-66 Factory Air Restoration

[HOTFUN]

I am a bit challenged at this subject but want to learn the best way to pull this upgrade off and keep the original functionality in place. I am now tearing apart a complete 1966 factory air system and have several parts AC trucks with them to compare. I want to restore the original system but plan to update the compressor to the new style 10 cylinder replacement for the original A6 using original brackets. Then I want to upgrade the old style worm gear clamp hose situation by having new O ring style nut fittings installed on the ends of the existing evaporator core, air compressor manifold muffler line, and forward connections. After researching this, I am told a new slightly larger ac condensor is what I need to make the use of R134 very effective. Questions I have now has anyone seen and used the retro fit kits that LMC or Classic Trucks have listed that is the condensor, dryer, lines in one kit and a new evaporator core with the new style valve? The descriptions are very lame on their sites but it appears they have an aluminum tube line set up and may use the nut style O ring fittings with these items? I have found that new fittings of all types are available right from the auto parts stores and new Parker AC hose so they can be professionally aluminum welded on the ends of existing barbed ends and after making the correct length of hose they hose can be professional crimped for a great easily serviceable system.
Maybe someone can expand on this or refer me to an existing thread that talks about this? Otherwise I think this could be a great FAQ topic and I maybe able to document lengths, fittings and parts used. Maybe someone should put together a complete upgrade package with detailed instructions? Thanks

[chevyguys]

I am doing this exact same project. The replacement evaporator core for these trucks has fittings and includes the bolt on nipple for those that wish to use a factory type setup.

To use a stock core you would just need to cut off the hose nipple and weld a replacement fitting on. Keep in mind that you only have to do this to the core nipple, the other one is bolt on from the factory. So far it's been fairly easy. I just purchased the full condensor kit and am using a sandon compressor. Total investment about 650.00. I'm about ready to install the evaporator box in the next few weeks and will take a ton of pictures of the whole setup.

[LT1 Burb]

I am an HVAC service guy so will be doing my own rebuild but I am planning on using my stock condenser. It should be fine everywhere except the desert for most of the year.I have done plenty of 134A conversions and never changed the condenser, but I would like to keep the stock clamps also. I may just have to add gas every year but I have plenty of it so no big deal.

[64fleetside]

I used a condenser kit for 64-66 from Old Air in Ft Worth. Looks real simlilar to OE, except modern R134a type tubes-parallel flow verses tube and fin originally. Fit was fantastic. I used O-ring fittings instead of clamp-type(had Old Air TIG o-ring fittings to a new repro evaporator), the new condenser uses o-ring type fittings. Puts out 42* air when its 100* outside.

[LT1 Burb]

The condenser in my suburban is out of a mid 90's chevy car, I just sourced it based on size from a Carquest catalog.

[HOTFUN]

I looked over all the pieces today. I feel my system may still have been pretty healthy still since it held a pretty good R12 charge when I broke open the first fitting. I'm leaning toward having the line fitting end welded on the high pressure side of the evap core and flush it out with ac flush. Replace the expansion valve and then have a fitting welded to the extension piece. Then I am thinking of having the new Parker hoses all the way out with crimped fittings/connections and it still will have an original look to it with the hoses clamped back as original. I have seen some restored Chevelles and Camaro's with the new style replacement A6 compressor painted black in original brackets and original Frigidaire decal shaped over the cylinder. Not 100% correct but will look very era correct. I will update to a new condensor with all new fitting connections to the dryer and should be set. Now the questions/ideas arise involving changing the original R12 fittings on the original compressor line manifold/muffler to 134 style if possible? or just move them to a less visible location? Second will be the correct type and amount of compressor oil for the all new or flushed out system and third the amount of R134 in a system designed for 3.75 lbs of R12 originally? Understanding a new style compressor may have a recommended oil type and I suppose R134 may have to be trial by thermometer in vent and pressure guages to determine net freon required. Thoughts? Thanks for all the great feedback so far.

[LT1 Burb]

The new oil is POE so you will have to drain all of the old mineral oil out. Best way is to measure the amount of oil you take out of the compressor and put an equal amount back in plus maybe an ounce. You will probably end up in the 4# range I would suspect but add 3 and go from there.

[Metalaroundstone]

I am a bit confused about replacing the compressor oil when converting to 134a. Is there an oil reservoir in all compressors, or only in the newer types. I am planning on using my original compressor (Frigidare 6550113)? Does it have a reservoir of mineral oil that needs to be replaced with POE oil? I see that some cans of 134a refrigerant include the oil. When using these, do I still add oil separately to the compressor? Also, are there seals inside the compressor that need to be changed when converting to 134a?

Enlightenment please.

[NEWFISHER]

I have done several r12 to r134a conversions and use this method: R12 total system requirement x 80% = amount of r134a + 3.oz of POE or synthetic pag oil. For a large condenser and dual evaporator systems like the newer Suburban's I use 4oz of oil.

The oil is added before the charge of r134a and is suspended in the refrigerant. It lubricates the compressor and Orings. Early on, shops would recommend that all orings, dryer, compressor etc needed changed to do the conversion. I have never had a problem using the existing components and using Pag oil and the 80% formula.

[tincan1966]

We do a lot of A/C work and custom conversions, too. I totally agree with Newfisher up to the part about not replacing certain parts.

Used, older A6 compressors don't normally last very long after being converted to R134A, due to increased cylinder pressure internally. They are also prone to leakage thru the front seal. The upgrade to the A10 wold be a smart choice, and to answer a previous question- you will add the recommended amount of oil directly to the compressor into the suction port before installing it.

We strongly recommendthe receiver dryer be replaced, especially if the system has been open for any significant length of time. The reasoning is that there is no way to clean the desiccant filter inside it. There is also no way to remove all the mineral oil from it. There have been instances where the old mineral oil and the new PAG oil will gel, and not circulate. We also flush all the lines and condenser, unless we are installing a new one
An average receiver drier only costs about $20
The molecular structure of the R134A is also the reason for the o-ring type fittings, as opposed to the hose clamp type, to help reduce leakage.

This is just how we do it here, since we have to guarantee our work- and don't want to be replacing parts or recharging systems every year for free.

[Metalaroundstone]

Very helpful, thanks. It seems like the more I learn about this the more questions I have. In reading more about the oil used in AC systems, it would seem that mineral oil, which was used in our old systems is incompatible with the 134a and also with the PAG oil. Apparently if you put PAG oil in a 134a system that also has some mineral oil, the mineral oil will just settle to a low spot and do nothing in the way of lubricating the system. However, I have seen a few recommendations to use Ester oil instead of PAG oil if your system had mineral oil to start with. Apparently Ester oil is more compatible with mineral oil. Anybody know any more about this?

It would seem that the best thing to do is to flush out as much mineral oil as possible and then your can fill the system with either PAG or Ester. However, I would think that it would not be recommended to do too much in the way of flushing the compressor other than just draining it.
The manual calls for a total of 11 oz of oil, (6 oz for compressor, 3 oz for evaporator, 1 oz for condenser, and 1 oz for dryer)

What viscosity of PAG or ester oil is recommended?
The original viscosity of the mineral oil was 525

[Metalaroundstone]

I just finished talking my factory AC evaporator box apart. I noticed what looks like adhesive lines on inside of the top lid of the evaporator as you can see in the photo. It looks like these adhesive beads once held up some insulation of some sort. Does anyone know there should be a layer of insulation here? And if so, what kind?

One of the main issues with the evaporator box was that the temperature sending wire from the thermostatic switch got tangled up with the vent flap, making it impossible to actually turn the AC off. The PO went in and added a toggle switch on the dash instead of actually fixing the problem. Any ideas on how the sending wire was shaped from the factory? I think it had a little clip that stuck into the fins of the evaporator, but mine has slipped loose.

Thanks for your help.

[chevyrestoguy]

I've pulled two of those evaporator housings apart, and neither one had any insulation material on the inside of the lid. Not to say that Chevy never did it, but on the two I did, it wasn't there.

The end of the temperature thermocouple routes down through the lid and gets secured to the fins of the evaporator. Mine had clips. If yours are missing, I think you could get creative and use a bobby pin or a paper clip to do the job. I'm at work right now, and I can't view any of the pictures, but if you look at my '64 build thread, I posted pictures when I restored my evaporator box. Check post#s 269, 287, and 299. Hopefully, they can answer some of your questions.

[Metalaroundstone]

Thanks chevyrestoguy,
It makes it a lot easier not to worry about more insulation. Do you have any recommendations for the gaskets for the sides and bottom of the evaporator and also between the return air duct and the firewall?
I have attached a picture of my evaporator showing the only clip that was laying on the bottom of the box. It is just a plastic spike with a little groove that the sending wire snaps into. From the looks of the fins on the evaporator, it looks like 4 of these spikes were used. Should the sending wire form an "S" in front of the evaporator?

[64fleetside]

There was a rubber lining on the top lid to keep it from sweating, I've only seen one still intact. The switch sensing tube did form a figure "S" in front of the evap. I hot glued all that stuff to keep it in place.

[chevyrestoguy]

Originally Posted by Metalaroundstone

Thanks chevyrestoguy,
......Do you have any recommendations for the gaskets for the sides and bottom of the evaporator and also between the return air duct and the firewall?

Nobody makes any of those gaskets, so I went to Lowes and bought a sheet of 1/2" thick rubberized foam (Armaflex), which is used to cover HVAC ducting. I cut a gasket to cover the oval hole in the evaporator housing where the fittings come out. For the gasket where the evap housing meets the firewall, I bought a roll of 1/2" wide door weatherstrip foam, and made a gasket. It's the foam with the adhesive backing for sealing windows and doors.

My A/C was dealer-installed in '64, and the techs that cut the holes did not do a very clean job. The holes were mislocated and they hogged them out to fit. I welded up their mess and fixed the holes and wound up using bulkhead grommets for the evap lines. I wanted things nice and tight, and I wanted to keep air leaks to a minimum.

[Metalaroundstone]

Originally Posted by 64fleetside

There was a rubber lining on the top lid to keep it from sweating, I've only seen one still intact. The switch sensing tube did form a figure "S" in front of the evap. I hot glued all that stuff to keep it in place.

Did you put anything rubber or other lining on the lid when you rebuilt the evaporator? If so, what did you use? If not, does condensation form on the lid? When you said that there was a layer of rubber, I was wondering if spraying the inside of the lid with Plasti Dip would insulate it enough to prevent condensation. I doubt if you could get a buildup of over 1 mil with the Plasti Dip.
Thanks for the info.

[Metalaroundstone]

Originally Posted by chevyrestoguy

Nobody makes any of those gaskets, so I went to Lowes and bought a sheet of 1/2" thick rubberized foam (Armaflex), which is used to cover HVAC ducting. I cut a gasket to cover the oval hole in the evaporator housing where the fittings come out. For the gasket where the evap housing meets the firewall, I bought a roll of 1/2" wide door weatherstrip foam, and made a gasket. It's the foam with the adhesive backing for sealing windows and doors.

My A/C was dealer-installed in '64, and the techs that cut the holes did not do a very clean job. The holes were mislocated and they hogged them out to fit. I welded up their mess and fixed the holes and wound up using bulkhead grommets for the evap lines. I wanted things nice and tight, and I wanted to keep air leaks to a minimum.

Chevyrestoguy,
Your information has been extremely helpful. On your build site It looked like you used Rustoleum 2K Black to paint the metal evaporator parts (I may have got this wrong). Or did you use automotive paint? The pics of your finished AC unit looks awesome.
I really appreciate your help.

[chevyrestoguy]

Yes, I used Rustoleum 2x. I was trying to save my gallon of "good" automotive chassis black for some other parts, and I figured that because the evap box was inside of the truck and out of the elements, rattle can paint would be OK. Rustoleum 2X is pretty decent on metal parts, especially if you use a metal etch primer underneath and give it a light scuff before you top coat it.

I wound up putting a piece of Peel & Seal under the evaporator to isolate the fins from the plastic housing. Peel & Seal is the product you can buy in the roofing section at Lowes that lots of guys have used instead of the expensive DynaMat products. Maybe you could do the inside of the lid with this as well? It works as an insulator to keep heat out, and it should serve the same function by keeping the cold inside the evap housing and not cause the lid to sweat. Now I'm thinking that I should have done the inside of my lid, too.

[Metalaroundstone]

I also noticed that the main vent flap (the one connected to the AC on/off switch also had the adhesive lines on both sides. I assume this also had some kind of seal, which is now long gone.

[Todd W. White]

Does anyone have a document, video, or website (or just pictures) of a detailed installation of the factory A/C system into a 64-66 truck that didn't have it originally?

[corvettejim1968]

i would recommend buying this book.

[Todd W. White]

I did buy the book, and it is nice, but it is not as detailed or thorough as I would like it to be.

[cortcomp]

"I feel my system may still have been pretty healthy still since it held a pretty good R12 charge when I broke open the first fitting."

You mean it had a good charge when your recovery machine was connected and sucked it all out per regulations