Re: 56 A/C info
Posted by HH56 On 2016/4/27 9:33:16
I used a commercial product from a supply house but that was years ago. Don't remember but it may have been Flexane as that was a product I used on many things back then. If I were to do it again I would use one of the Smooth On brushable productshttps://www.smooth-on.com/product-line/brush-on/ Their Brush On 35A or 40A would be my choice. 35 is at the top end of the soft category and 40 is at lower medium -- roughly equivalent to pencil eraser hardness.
A trial unit contains way more urethane than you would need to seal the seam and give the item a layer or two. It is easy to mix by volume so you can mix what you need and keep the rest -- although it does have a limited shelf life and once opened, even less. You can order online or there may be a showroom for SmoothOn or for the Reynolds Advanced Materials distributorship in your area. Urethane sticks to everything and color may be an issue. IIRC some of SmoothOn urethanes are brownish so you might also need a small bottle of black colorant and probably a mold release agent for the wood or sheetmetal form.
I converted my car to R134A but since my original unit had been molested over the years it wasn't working and parts such as compressor valves and temp control valves are NLA. I cheated by copying and building an entire unit from scratch using all modern components. Put the original on the shelf in case the car is sold and someone wants to spend the money and try to go back to stock.
My compressor and modulator valve were the big issues. Had considered keeping the evaporator and just getting a new Sanden compressor with clutch control for temp adjust. Since the expansion valve and new hoses were also needed and the old unit had flare fittings, I decided to go to all modern with components having O ring fittings and to use barrier hose.
R134 has a much tinier molecule than R12 and will leak in places where R12 won't. There are some who have successfully converted using their original components. With a well thought out approach it can be done. Most of those converted units I suspect have have been on later cars with newer type hoses and fittings etc than our old Packards. Not only are our hoses old but they are made of materials not necessarily impermeable to R134. Flare fittings are another known source of leaks because of the higher pressures with R134 but are not the biggest source of issues.
The old oil is not compatible with R134 so has to change and whether 60 years of the old stuff has permeated thruout the components to the point it can't be completely flushed and will contaminate the new is another unknown or potential issue. There are some oils that are supposed to be able to work with both refrigerants but no idea if they are as good as claimed or if they are compatible with the old oil.
All in all, there are a myriad of issues with converting old units and the reason I suspect your AC guys are not wanting to do it. Fix one compatibility problem and another problem or maybe a leak crops up. It could be more than they want to warranty or tackle. As to finding R12, out here at least it is licensed, only comes in large containers, and can only be purchased and installed thru a licensed shop having the filling and recycling equipment to completely control and account for every last drop used. It is almost a hanging offense for a DIY to have the stuff, not that many don't have left over stuff from the good old days, but just be careful not to get caught.
You might ask your AC guys if there are newer products on the market that can substitute for R134. I seem to recall EPA was on the verge of approving something else but haven't really followed progress after I did mine. At least one poster on site was or is promoting an industrial variant of R12 as an acceptable substitute but whether that is sanctioned or shadetree is unknown.
Here is the unit I built. The flexible foam ducts were cast in molds and made with FoamIt, another SmoothOn product.
Attach file:
(93.64 KB)
A trial unit contains way more urethane than you would need to seal the seam and give the item a layer or two. It is easy to mix by volume so you can mix what you need and keep the rest -- although it does have a limited shelf life and once opened, even less. You can order online or there may be a showroom for SmoothOn or for the Reynolds Advanced Materials distributorship in your area. Urethane sticks to everything and color may be an issue. IIRC some of SmoothOn urethanes are brownish so you might also need a small bottle of black colorant and probably a mold release agent for the wood or sheetmetal form.
I converted my car to R134A but since my original unit had been molested over the years it wasn't working and parts such as compressor valves and temp control valves are NLA. I cheated by copying and building an entire unit from scratch using all modern components. Put the original on the shelf in case the car is sold and someone wants to spend the money and try to go back to stock.
My compressor and modulator valve were the big issues. Had considered keeping the evaporator and just getting a new Sanden compressor with clutch control for temp adjust. Since the expansion valve and new hoses were also needed and the old unit had flare fittings, I decided to go to all modern with components having O ring fittings and to use barrier hose.
R134 has a much tinier molecule than R12 and will leak in places where R12 won't. There are some who have successfully converted using their original components. With a well thought out approach it can be done. Most of those converted units I suspect have have been on later cars with newer type hoses and fittings etc than our old Packards. Not only are our hoses old but they are made of materials not necessarily impermeable to R134. Flare fittings are another known source of leaks because of the higher pressures with R134 but are not the biggest source of issues.
The old oil is not compatible with R134 so has to change and whether 60 years of the old stuff has permeated thruout the components to the point it can't be completely flushed and will contaminate the new is another unknown or potential issue. There are some oils that are supposed to be able to work with both refrigerants but no idea if they are as good as claimed or if they are compatible with the old oil.
All in all, there are a myriad of issues with converting old units and the reason I suspect your AC guys are not wanting to do it. Fix one compatibility problem and another problem or maybe a leak crops up. It could be more than they want to warranty or tackle. As to finding R12, out here at least it is licensed, only comes in large containers, and can only be purchased and installed thru a licensed shop having the filling and recycling equipment to completely control and account for every last drop used. It is almost a hanging offense for a DIY to have the stuff, not that many don't have left over stuff from the good old days, but just be careful not to get caught.
You might ask your AC guys if there are newer products on the market that can substitute for R134. I seem to recall EPA was on the verge of approving something else but haven't really followed progress after I did mine. At least one poster on site was or is promoting an industrial variant of R12 as an acceptable substitute but whether that is sanctioned or shadetree is unknown.
Here is the unit I built. The flexible foam ducts were cast in molds and made with FoamIt, another SmoothOn product.
Attach file:
(93.64 KB)
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