dplotkin

There are many out there who insist 134 does not cool as well, cool well at idle, cool well on cars with steel condensers, I've heard all the BS and its all BS.

If you need an electric fan to make 134 work its because you have an existing fan/condensor air flow problem or a problem with the refrigeration system, not because the system does not like 134. I cannot speak for A/C in a C2 as I don't have one but its substantially the same as that in my Bonneville.

The Chrysler & Bonneville are completely stock, steel condenser cars with no extra fans. Both cool to 38 degree vent temps with high side operating roughly 2.5 X ambient temp, as it should be.

There is no reason to run 12 unless you have a 12 system on 12 performing nicely. I have 2 of those & I top them off with 12 every 3-5 years. The Bonneville has been on 134 for 6 years and has never needed a top off yet.

Dan

beekppr

Sounds good. R134 would be easier since the new compressor already has the correct oil in it. My car came to me missing most of the AC components so getting it operating meant starting from scratch but that also leaves me more options in the setup. The only original pieces being used are the STV valve and evaporator and both will be squeaky clean when I'm done. Soon, I'll have only the hoses left to do before vacuuming it down for charging. Because I'm using a different condenser, compressor and dryer, I'll have to custom make the hoses but the tech guy at Old Air assured me it wasn't that hard and they sell everything I need to do it right myself.

pop23235

There is a difference in R-12 hose and R-134 hose. I haven't bought any in a long while, but I'd bet R-12 hose is discontinued. It should be. It's porous compared to the lined R-134 hose.

Powershift

Yes, the older hoses used for R12 can leak a bit of R134a refrigerant when new since the 134a molecule is smaller and can get thru the pores in the hose. R134a hoses have an internal barrier lining.

However, extensive testing hs shown that the refrigerant oil used in R12 refrigerant service will ultimately coat the inside of the R12 hoses and seal the pores. So a USED R12 hose is okay for R134a.

Believe it or not...............

Larry

wmf62

all the horrible things that were said about converting R12 systems over to R134a never happened...

Bill

bg3500

Years ago I used the stv eliminator and it never cooled satisfactory in my 66 vert. This was with r12. The compressor constantly cycled . Last month I rebuilt my stv with a new diaphram and used esther oil with new compressor, drier and r134a. Vent temps at 42 now and low side is at 30. I probably should tweak the stv spring to get low side down some, but decided to leave well enough alone. The stv are said to be unreliable but we will see

bg

Powershift

I also prefer to stick with factory installed AC components. However, it appears that the constant cycling you experienced was due to a undercharged system (low on R12) or the eliminator kit was defective or set incorrectly.

There are a number of folks that report success with the STV eliminator kits, but I do not recommend them to others if at all possible. Fix what is broke first.

You persevered and were successful. Congratulations.

Larry

domenic tallarita

Thought I would show a oil that we are using that is good for both, R-12 & R-134. Less corrosion with this.
Make up your own minds, just some info.

Dom

beekppr

Working on the AC again today and my plan is to flush the evaporator. I have studied the assembly manual and done some research but I guess my question must be so basic that it wasn't covered much in detail.

Am I correct in believing that the normal flow direction of refrigerant would enter the evaporator at the bottom at the expansion valve and exit the evaporator at the top and into the STV? I have the STV and the expansion valve off so I'm ready to flush the evaporator.

Based on what I've seen in videos, it is best to flush in the opposite direction on normal flow to get contamination out the way it came in. Is this good information?

Lastly, there is a small tube exiting the bottom of the evaporator and winding its way up to the body of the STV. Flush this tube as well? I'm guessing I can flush as I described but block the lower outlet a bit so the solvent is forced up through the smaller tube. Any thoughts?

I'm doing several other things to the car today so I'll hold off on the flush until I get an opinion or two.

Thanks everyone!

Powershift

1. Yes

2. Yes

3. I would flush from STV down. This is an oil return tube from the bottom of the evaporator to the STV.

Larry

dplotkin

I concur with Larry. Don't flush the compressor, you don't want solvent trapped inside it. Do send out your dryer for a new bag of desiccant. Real important no moisture is in the system as it will freeze and can obstruct the TX valve.


Beyond that...assemble the system and pull a vacuum. Leave it sucked down as long as you can to verify tightness & dry it out and charge into the vacuum, always. Make sure you purge the lines on the charging station/gauge set before you do. Better to slightly undercharge than overcharge & break the compressor.


Dan

beekppr

Sounds good. I'm using a new compressor, condenser, dryer, valves, and I still have to make new hoses. I'm leaving the new items sealed until the end as they pressurized them with nitrogen. I'm a little away from charging still. I'm slowly getting everything as perfect as I can as I go...I'm in no hurry. I always screw things up when I rush.

beekppr

Just flushed a whole quart through the evaporator. Fluid went from clear to yellow so I'm assuming that's old oil. There were lots of crumbs of junk coming out too so I'm glad I didn't skip this step. Even at the end, it was still slightly yellow so it's probably a good idea to run a second can of flush through it.

beekppr

Had to flush the evaporator twice to get it nice and clean. Installed a new expansion valve and the rebuilt STV unit. Everything is about ready for me to make new hoses.

I had a question about the muffler seen on some stock GM hoses coming out of the compressor. I don't generally see them on systems like mine with a newer style compressor. I understand that it was designed to dampen pulses coming out of the compressor but is it really necessary on a newer compressor like the pro6ten I'm using? I read somewhere that a longer ac hose also tends to dampen out the pulses and it seems like my hose will be a fairly long run all the way to the front.

Also, does anyone know if I need a fitting block on the back of the pro6ten compressor. It's charged with nitrogen and I didn't want to remove the back plate to examine it until I'm ready to install new hoses.