Ad0911

I read a lot in this forum about changing refrigerant from the old R12 to other stuff like R134a and R123.
Mostly, changing from R12 to another refrigerant like R134a requires a lot of parts to be changed in the system.

Now I heard about R437a as an alternative to R12. It is said that you don't need to change O-rings and other hardware. It is a real alternative.

Anybody with any experience with this gas?

http://www.linde-gas.com/en/products...37A/index.html

Ad0911

While I had the blower motor out to clean up behind it, I made pictures inside and was really shocked with what I saw. The lamellae (I don't know the english word for it) seemed to be flattend so no air can get past. This looks bad! How can I get to the core? Can I get the airbox out?

WallyP

R437A refrigerant is mostly R-134a, and as such will not work with the original mineral oil.
Blends of refrigerant have a problem with differential leakage - the smaller molecules leak out first, so eventually you end up with a different blend. No way to get back to the intended blend other than dump and start over.

Most of us can't give you any real-world experience with R437A, as it is not legal here in the USA. Our legal system can seem strange to you folks - that's OK, it seems strange to us as well. It would be very difficult to find a commercial shop who will touch a car with anything other than R-134a.

19psi

If you have R-414B available in your area, that would be a better alternative. It's also known as Hot Shot.

Are those pictures of your evaporator coil?!?

dr bob

The pictures of the heat exchanger fins don't look good. Looks like something was dragged across them, or it was dragged across something during installation or maintenance. Maybe the arm of a mechanic reaching in to change a blowere resistor? Regardless of the cause, with the fins folded over like that, airflow is blocked.

In the US we can find a comb for the fins, referred to as a "fin straightener". It's more for straightening an area where something rubbed against the fins, but requires that you have a normal area to start with the fingers of the tool, then gently work the tool up and down through the fins to bend them straight again. While it might be possible to get your straightened, it will be really tough to do it in place. But worth a try. A Google search for "radiator fin straightener" brings up an array of the tools. Look carefully for one that might work in the confines of the blower duct. It may be the one with a removable head could be cut to separate the comb with the right pitch for your fins to use in the ductwork there.

dr bob

On changing refrigerants, I'll build a little on what Wally shares.

Most of us only think about changing from R12 after the old refrigerant has leaked out to the point where there is no longer adequate cooling. There is a fraction of owners who are restoring a system that's been damaged, certainly the minority. In the US, legal options are very limited. Practical option is limited t R-134a right now, if you ever anticipate having a commercial service shop work on the system in the car. With that in mind, you need to fix the leaks in the system before you put anything back in.

Fixing the leaks starts out with, at a minimum, replacing the o-ring seals at the connection points in the system. It's easier to find and install the modern o-rings than to locate original types. With few exceptions (fuel cooler snaps to mind), the o-rings can be sourced at a local parts store pretty easily. Our favorite vendors in the US have assembled kits of these o-rings, so you can get the right ones with a phone call.

Whenever the system is opened to atmosphere, it's good practice to replace the receiver/dryer. The currently available replacements have dessicant compatible with both R12 and R-134a, so no worries about which to choose.

The decision on refrigerants drives the next step, which is cleaning/flushing the condenser and evaporator. The inside walls of the tubes end up with a thin film of mineral oil on them, oil that is normally transported by the refrigerant to lubricate the compressor. Mineral oil is not miscible in R-134a, so it won't travel in the refrigrant stream. It's not fatal if you choose not to flush the old stuff out, it's just good practice. The decision on replacement oil is driven by this decision however; if you don't completely flush the old oil out of the system, you must not use PAG oil to refill. It doesn't mix with mineral oil, and in fact will form a jelly when they try to blend. Instead, use easily available polyolester (POE) lubricant, which is compatible with both R12 and R-134a.

So now that we've solved the problem of the leakage that caused us to work on the system, all that's left is the choice of refrigerant. R12 is much tougher to find compared with R-134a. Local Big Lots store sells 14oz cans of R-134a for $7, and you'll need three and probably four cans to allow for purge quantities. Big-box store Sams Club sells a 30lb commercial-size cylinder of it for $85. Roger stocks small R12 cannisters, but I don't know the current prices. IIRC he was at somewhere around $15/can last time it came up, and it takes at least four to fill the system.


So back to the original subject-- Why would you choose a refrigerant blend, or a propane blend, or an isobutane blend, when easily found and serviceable R-134a is so readily available, and takes no more work to install properly than any of the others including R12?

Ad0911

Thanks dr Bob for your views on the fins.
In order to get to the fins ti straighten them out with the comb, I'll have to remove the airbox, right? To remove the airbox I'll have to disconnect the pipes for the refrigerant gas. Correct? And ifI read the PET right (page 321 of the 1982 version) the airbox can be split in half, correct? The front canbe taken off after removal of the ac lines and vacuum actuators. Has someone ever done this succesfully?

Speedtoys

The only good way to do this, is swap to 134, because no matter what, you should be changing the oring seals. Its not that bad. 4-6hrs will do it, add 2-3 more for rear ac.

Your fins are not that bad, just the angle IMHO.

Ad0911

I guess my next job is the job I really did not want to do when I started this project, and that is taking out the dashboard. There is no other way to fix the fins from the heat exchanger.
From the PET and what I see in the car it looks like the ventilation housing can only be extracted from the car from inside the cabin (under the dash) not from outside (engine compartment). Now the pod is out it seems like the one chance I have to pull this off. I checked the WSM Vol.4 repairgroup 87, which covers the AC. It only does not completely cover how to take out the dashboard. It seems like a big part of that procedure was left out.
Is there a good writeup on how to take the dash cover out to get to the AC heat exchanger / evaporator? Or a writeup how o remove the heat exchanger?

Speedtoys

What amount of fins need "fixed" here?

dr bob

If you haven't already done so (covered in the 'new users' thread), start bokkmarking users' tip sites. At http://www.nichols.nu/tips.htm Greg shares posts and hints that relate to the dash removal.

Hilton

When I pulled my heater box apart ( to fix a broken comb flap arm), I used this dash removal guide:

http://landsharkoz.com/forms/928_dash_removal.pdf

Ad0911

Did you see the picture from my earlier post? Picture taken with my smartphone. It looks like they are all bent to the point where they block the airflow. I'll go in from the side with my endoscope camera to see better.

Speedtoys

Did you read my response? Its just a bad angle.