Hig116

When I purchased my '72, the previous owner told me he had converted the ac to r134a, but the compressor was currently locked up. I removed the compressor when I rebuilt the motor and am ready to replace it and see if the system will work. I'm not sure what I need to do to complete this. Do I need a stock compressor and then parts to convert it or is there a compressor I can buy that is already r134a that will plug/play? Are there any other parts that I'll need to replace since the system has been empty for years? Will I be able to recharge or do I need a shop to do it?

Thanks,
Keith

centralcalvette

R134 is a drop in replacement for R12. I'm getting rusty, but as I recall, you want to charge it to about 85% of the stock charge (weight). You'll want to verify this. So, what ever compressor you buy will work, but today, it would probably already be set up for R134. If the compressor seized, you'll want to flush the system with AC flush and then dry it out with air. This is because the compressor probably spewed metal in your ac system.

To correctly flush the system, you'll want to disconnect every connection and flush each line and reassemble with new o rings. You'll want to remove the POA when you do this. The evaporator needs to be flushed WELL. The condenser needs to be flushed VERY WELL. New condensers have very, very tiny pathways for the refrigerant to flow. This style cannot be flushed. While you probably don't have a "new" style condenser, you may consider replacement anyway.

You could charge it yourself, you'll need a vacuum pump, gauges and a refrigerant scale. It may be better to pay someone to do it for you.

You'll absolutely need to replace the dryer.

Tampa Jerry

If you are not going to have the car judged or are not concerned about originality, consider a Sanden compressor. They are much lighter, less expensive, more efficient and do not run all the time when the AC is on. I have one in my small block 68 and I love it. Jerry

Hig116

Thank you both. I failed to say that originality was not a concern. I'll look into the Sanden. Fortunately, I just spoke to an a/c friend who will help me charge it and has the equipment. Now I just need the parts and time to get it ready for him

Thanks again,
Keith

derekderek

this compressor. do not buy serpentine version. the v belt clutch costs as much as the compressor. https://www.ebay.com/itm/36228687978...AAAOSwHqdaxRcw problem is the hoses. they would hit the hood if you bought hoses to fit. so you buy a Q head instead and hook up your existing hoses. https://www.partdeal.com/omega-sande...0aAiX2EALw_wcB i haven't tried yet but i hear this compressor will mont to the front mount of your A6 compressor. or the 709 sanden which is a bigger compressor in essentially the same size body. now, your black hoses. they are 50 years old. my 75's were ripped right open. and they were 3 years younger. these hoses are a failure point. in fact, point 2 after the compressor. and ditching the POA valve for the eliminator is a good idea. should have called it POS instead of POA. but then they tried VIR which was a bogger POS than POA ever was...

Mark G

The main other components would be to check your evap to make sure it's a micro-channel parallel flow unit. Then replace the hoses (if they're original or non-barrier hose), and accumulator. And flush everything out and use whatever oil your new compressor calls for (they're different). Chances are the previous conversion used POE oil ...if you replace the compressor and evap. If it looks like they were really thorough, that will cut down your work. If it was a quickie job before, you might as well do the rest and FLUSH out the evap completely. Use the right oil this time (only with new hoses though). Just about any condenser you buy these days will probably be micro-channel. But quadruple check what's on your car.

Here's more detailed info. Obviously just quickie info, others might have further suggestions:

1) Compressor - Looks like you have this covered already. They make A6 compressors which will work for your car and 134. Should be ok. 90% are going to tell you to buy a Sanden. And that would be great, but you're talking more $ and retrofit (and non-original look). But good advice if you are inclined to go that way. However, if you search the forums, a lot of guys have good results with a Delco reman or new with updated pump seal (one main weakness on them was the front pump seal). They'd leak out back in the day even with R12. And these compressor were HEAVY. But an improved GM Delco should do the trick for your occasional needs. But only you can decide the route you want to go. You need to quadruple-check the oil you'd need. That depends on the compressor. You probably have no idea what's in there and they're not all compatible. If you go with a Harrison compressor you should use PAG150. I know Delco heavily states what oil must be used per their style compressor. So whatever compressor you look at, get the right oil. I would just buy AC Delco compressor and Delco oils. Then you know it'll be right.

2) Hoses - Have they been replaced? You might want to look at them. If they're original, get new hose put on. Some AC shops will do that for you for cheap. Old hoses can have mineral oil soaked into them and that can react with PAG. Plus, 134 will seep through those old hoses. New "barrier" hose is superior. If you use an original style compressor, than you could buy new hoses too, and they'll be barrier hose.

3) Condenser - The right condenser is a MUST if you want the 134a system to work well. I remember years ago when my truck was converted and I didn't replace the condenser (micro-channel condensers were new and $$ back then), it didn't cool very well at all. R12-style condensers like your car would have come with, were like a coil where you could roll a bearing through the whole thing. There isn't enough surface area on an R12-system condenser for 134a. The new condensers are micro-channel technology ....basically extruded aluminum with about 8 or more small holes (channels) for refrigerant to flow. They can have up to 12x more heat dissipation surface area. Parallel-flow is a must. Most condensers have switched over to micro-channel (and parallel flow) a long time ago so you should be able to find one that is a direct fit that will work for a 134a conversion. You should be able to inspect if yours has been converted to parallel-flow/micro-channel by looking at the ends of the condenser. The horizontal micro-channel aluminum sections will look like a flat bar going into a vertical manifold on each side.

4) Accumulator - Again, you need to replace this too. It would have oil in it, an maybe not the correct type of oil. Plus you need it to soak up any residual moisture.

5) Valving - I'm not sure about the valving your car has. Hopefully someone else can chime in.

6) Evaporator - Unless you intend on removing the evaporator (inside piece), you should at least flush it out very THOROUGHLY. Unless you know exactly what type oil the P/O used. There's a device to do this (plus the right AC flush solvent):
7) Vacuum - Obviously you'll have to pull at least two deep vacuum's on it before charging. (best to let sit overnight or a full day to ensure it's holds the same vacuum -- no leaks).

8) Retrofit Kits - A DIY conversion can work real well. Depending on how much time/money/effort ...and your expectations, perhaps a route to consider is to buy a pre-engineered kit with the right parts and pieces. They're expensive but lowers your risk and might improve outcome. That said, if you what I've (and others) have suggested, your 134a conversion should work ok.

9) Farm it out (??) - Another route to consider is to find a local shop which does a lot of AC work and retrofits. Drive your car there ...talk to the owner/tech in advance about what you want to do and the best way to go. Let them ID your current condenser coil, hoses. Maybe he can determine what you have and need. Perhaps you can buy the parts and install them yourself and let them do the finish work? Or they can buy/install them and give you a warranty?? AC shops are geared up with superior flushing and recharging equipment and a good understanding of how the AC system should function. You'll probably have better results by them doing at least the finish refrigeration work. If you don't get a good feeling about a particular shop, go to another one. At the very least you'll probably learn something that might save you from making a mistake ...even if you end up doing it all yourself. They know the good parts from the crap, and can hopefully steer you in the right direction.

Summary - Do additional google searches, there's tons of really good conversion info out there. Add 'forums' after your search string and you'll get just forum posts. You'll get a lot of very useful info. And search youtube videos too.

.

4-vettes

With all the above. Take a look at my air-con thread. "73-E77 Air-Con upgrade". It's worth a look.

Mark G

It's entirely possible the compressor locked b/c the previous owner (or shop) didn't flush the system well enough which mixed incompatible oils. Thats why I say you really can't flush it too much.

A guy really needs to remove the compressor and dump out the old mineral oil, then flush it out well. Actually that probably isn't even good enough. A guy should really disassemble the entire R12 compressor, clean all that old oil out, install new seals and put in new PAG oil ...or better yet, buy a new (rebuilt) compressor (and know exactly what oil the supplier shipped with the new compressor). And get rid of the old mineral oil-soaked hoses. And make sure the other components which can hold oil are flushed out (thoroughly) ...or replaced with new.

Or the P/O may not have used the right weight oil too. As I mentioned above, different compressors require specific weight oils. GM specifies PAG150 oil (or else!! lol)

Hig116

I just realized my emails to tell me I have replies have been going to "junk." Thanks everyone for the detail, as this is VERY helpful. I've been considering changing over to a Vintage Air system, as I fee like I could spend close to the same amount trying to get the stock system right, and would still have a system I may not be 100% confident in. Hmmm, decisions decisions.

Thanks again everyone. You guys rock!
Keith

stevedinino

Agree with the Sanden recommendation. They are cheap, light, plentiful and proven. The downside with those is the mounting brackets. You will need to come up with the hardware that align the new compressor pulley with the crank.

If you go that route, do yourself a favor and search for a rear exit version. Most seem to have fittings that point vertically, and there’s not a lot of clearance for hoses under there. I ended up replacing the head on mine for that reason.

Here’s an example:
Amazon

derekderek

or this version which fits OEM hoses. https://www.partdeal.com/omega-sande...hoCEP4QAvD_BwE there is a sanden conversion kit for about half the price of vintage air. leaves the evaporator and in-car ducting alone. just compressor, hoses, accumulator, etc. i pieced my system together cheaper, but not a lot cheaper and a lot of research. here it is. https://www.originalair.com/69-72-co...de-kit-stage-1