Trying to bring the A/C back to life.

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1994redram

1994redram

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I bought my 70 dart last summer and was so excited to own it I didn't mind not having A/C. But I would really like to get it going this spring. The slant 6 runs great and has had a full tune up performed. I've logged about 4500 miles on it since owning it. The drivetrain seems solid after it sat for 18 years. Last fall I replaced the heater valve, heater core and all of the HVAC box seals along with the vaccuum lines and push button switch. The heater is HOT and all of the doors function as they should. So hopefully I won't have any issues with the evaporator.

My car has factory A/C on it and it's all intact and hooked up. But it didn't have any Freon or pressure in it. I just bought the 134a conversion fittings, 134a compatible dryer, New O-ring kit, and expansion valve. I jumped the compressor lead and the clutch kicked on and the compressor spins. So I'm going to chance it and hope it's still good. Changing everything out was is straight forward and simple.

My question is how/should I flush the old oil and possible trash from the system? If there is anything.
How much oil should I add since I'm not replacing any major items? I bought some Esther oil so it's backwards compatible to the R-12 stuff.
Would my 1970 dart have an EPR valve? I've found a bunch of conflicting info about the EPR valve. Some say keep it, some say toss it. If it is really beneficial to toss it, I will and install a thermostat. But if its fine then I'll just let it be.

I've done A/C repair work in the past. But I'm not a pro so I would like to get my info from a pro before I waste money on Freon.
 
Change every o-ring in the system, vacuum it down.
See if it holds, if it does add freon.
I have brought quite a few old units back to life this way.
 
very likely needs compressor shaft seal. me? I'd gamble. course i have a stash of R "anything" lol
 
Hi,

I would take the compressor off the car, replace the shaft seal and its housing O ring. Then pull off the oil sump pan and see what it looks like in there. Watch the small ball check valve and spring when removing the pan. Clean things out with a little A/C flush solvent and put the pan back on with a new gasket. Fill it with 8 to 10 OZ of new Ester oil.

Most of the oil in the system is in the compressor and some will be trapped in the receiver/dryer which you are changing. While you are changing the O rings on the condenser fittings you can flush it with A/C flush solvent and blow it out with plenty of compressed air. That will get the little bit of old oil out.

Check all the hoses while you have things apart , you may want to consider having them rebuilt. The EPA wants you to add a high pressure cut-off switch on a R-134A conversion, this would be on the discharge side of the compressor. When you get it back together and vacuumed down, charge with R-134A to about 70-80% of the original R-12 capacity and see what your vent temperatures and system pressures look like. A 1970 will not have an EPR valve but, uses a cycling switch instead.

A factory service manual is a great guide to the working of this system and the RV-2 compressor.

Good luck and ask if you have anymore questions.
 
Pete in NH said:
Hi,

I would take the compressor off the car, replace the shaft seal and its housing O ring. Then pull off the oil sump pan and see what it looks like in there. Watch the small ball check valve and spring when removing the pan. Clean things out with a little A/C flush solvent and put the pan back on with a new gasket. Fill it with 8 to 10 OZ of new Ester oil.

Most of the oil in the system is in the compressor and some will be trapped in the receiver/dryer which you are changing. While you are changing the O rings on the condenser fittings you can flush it with A/C flush solvent and blow it out with plenty of compressed air. That will get the little bit of old oil out.

Check all the hoses while you have things apart , you may want to consider having them rebuilt. The EPA wants you to add a high pressure cut-off switch on a R-134A conversion, this would be on the discharge side of the compressor. When you get it back together and vacuumed down, charge with R-134A to about 70-80% of the original R-12 capacity and see what your vent temperatures and system pressures look like. A 1970 will not have an EPR valve but, uses a cycling switch instead.

A factory service manual is a great guide to the working of this system and the RV-2 compressor.

Good luck and ask if you have anymore questions.
Click to expand...

EXACTLY what I was looking for! Where is a good place to get the shaft seal and pan gasket? Are any of them superior to another?
 
In general RV-2 parts are getting harder to come by. I don't know if any one source is better than another if you can find what you need. Try Action AC at http://www.action-ac.com/ they list the RV-2 gasket set as MT-2110 and shaft seal as MT-2034. I don't think you can get the pan gasket separately anymore. My local NAPA used to have the shaft seal kits but, I haven't tried recently. You could try an internet search for RV-2 shaft seals. There also seem to be a number of EBay sellers that have them. I would be careful, though with real old stock as the big o ring may not be R-134A compatible.
 
Well I replaced all of the o-rings, drier, expansion valve and pulled a vacuum. Or at least attempted to pull a vacuum! It wouldn't pull any more than an inch of vacuum. So made a hose setup from an old manifold set and pumped compressed air in and found a large hole in the condenser! I pulled it out to inspect it and found the hole. Looks like it could be repaired. But I would rather upgrade it to a parallel flow condenser. People say it is far more efficient. I have a bmw 3 series parts car that had a working A/C system. The condenser is the same height as the factory dart piece. But it is two inches narrower. I don't really want to downgrade and use a smaller condener.

So does anybody have any experience with upgrading a condenser? It seems really straight forward. I think I just need to hit a salvage yard with some measurements and find something that'll fit.
 
ranshu.com
I didn't look it up, but this site has just about everything under the sun when it comes to A/C.
I found my evap for my Dart here, no problems.
 
I'd go with a standard (stock) piece. If you don't, and the A/C doesn't work properly after you get it together and charged, you will have to wonder if the problem is the condenser or something else. The stock one worked fine for years and years.
 
The factory AC "A" bodies did not have an EPR valve, they used a thermostatic switch to cycle the clutch and prevent evaporator freeze ups.
 
If your using R-134A, converting to a parallel flow condenser is a good idea. R-134A is not as efficient as R-12 in heat transfer and the old serpentine flow condenser can lead to higher discharge pressures at times.

There are universal parallel flow condensers available and you just need to find the biggest one that will fit in there. Also, having the radiator shroud and the factory A/C cooling fan in place will give you good air flow through the condenser. You will have to make up adaptors or new A/C hoses to match up to the new condenser.
 
I've found a few sites to buy universal condensers in multiple sizes. I'm going to see exactly how big I can fit in there and still have room to plumb it. I have my factory slant 6 cooling fan and shroud and the radiator was upgraded to aluminum, the OE radiator was full of sludge. If I have any cooling issues I'll remove the mechanical fan and go with an electric setup.

I did find a few places that sell new factory serpentine style condensers. But they are around $275 and up. Most of the big parallel universal condensers are around $75. And shouldn't cost anymore than another $75 to plumb.
 
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