Does RV2 compressor work with R134a using all new components?

[WH23G3G]

I've got my 73 400 Charger at a shop finishing up the things I couldn't fix myself. One is to get the a/c system working again since I'm in Georgia. When I did everything, I took out the evaporator box, rebuilt it, checked all the vacuum hoses/valves, installed new blower motor, new evaporator, and new heater core. Under the hood I used a remanufactured RV2 compressor, new clutch, new drier, new a/c condenser, new hoses, new expansion valve, and new pressure switch. The only thing I reused was the EPR valve in the compressor. I cleaned it and installed a new o-ring. I noticed Classic Auto Air recommends removing it completely and adding an electric thermostat. But it seems like they are showing that if you mount a rotary compressor and didn't mention the RV2 compressor. Has anyone been running R134a with an original RV2 and with the EPR valve installed and still having good luck with it?

[Nacho-RT74]

I have been using R134a since some years now on my my RV2 system with and without EPR valve. It works with both setups, BUT with EPR I noticed how on back of compressor was getting ice around the outlet, for a while without, just the water condensation.

without EPR and without Thermostat I have noticed inside the box the air flow sometimes get clogged MOSTLY SURE due the ice on evaporator... and get more water coming out the box ( inside the cab in fact ).

I guess humidity on your location can affect more or less on the ice you can get wherever it happens ( compressor outlet or evaporator )

Conclusion... I should keep the EPR or install the Thermostat. I didn't want to add anything else on my system/engine bay so mostly sure will get back to the EPR, since I prooved it works just fine.

I know they work at diff pressure and blah blah blah, but my experience was that it works just fine.

Note... Never changed or readjusted the expansion valve, allways have used the factory one.

[Pete in NH]

Hi,

My preference on any original R12 system is to leave it R12 as it always out performs a conversion to R134A unless you do a lot of work on the system. Okay, that being said, if you are going to R134A you did most of the required steps. What oil are you going to use? Also, your new dryer should be compatible R134A and likely will be if it's a recent unit. The original seals in the RV-2 were not R-134A compatible but if the unit was rebuilt using new seals you should be okay. On the EPR valve, there are two types out there one is not adjustable and the other is. The adjustable one has a little set screw and lock not in the center of the valve. If you are lucky enough to have the adjustable one, you can lower the EPR setting down to 22 LBS for R134A, the original setting is around 26 LBS.

If you don't have an adjustable one you can try it where it is at 26 LBS but if you remove it, as Nacho said the evaporator will likely freeze up. If you remove it you will need to go to a thermostat switch with the  sense probe installled in the fins of the evaporator core. This will cycle the compressor on and off to keep the evaporator from freezing . You can get adjustable thermostat switches to dial in the system. You'll also have to play around a bit with the amount of R-134A you put in the system compared to the original R-12 amount.

I learned automotive A/C work on my 71 Charger with is still R-12, with no plans to ever convert it. Those old RV-2 systems while a little noisy and heavy will run forever if cared for. Good luck with your project!

[Pete in NH]

By the way I forgot to add that the cycling switch system was the way Chrysler did the RV-2 systems in all the A body cars like Darts and Valiants. So, you have to wire the new thermostat switch in series with the compressor clutch power lead.

[Nacho-RT74]

as far I know the R12 will be out of the market pretty soon due contamination, thats why I did the conversion at least. I have known in Europe is not available anymore

[Dino]

I've got my 73 400 Charger at a shop finishing up the things I couldn't fix myself. One is to get the a/c system working again since I'm in Georgia. When I did everything, I took out the evaporator box, rebuilt it, checked all the vacuum hoses/valves, installed new blower motor, new evaporator, and new heater core. Under the hood I used a remanufactured RV2 compressor, new clutch, new drier, new a/c condenser, new hoses, new expansion valve, and new pressure switch. The only thing I reused was the EPR valve in the compressor. I cleaned it and installed a new o-ring. I noticed Classic Auto Air recommends removing it completely and adding an electric thermostat. But it seems like they are showing that if you mount a rotary compressor and didn't mention the RV2 compressor. Has anyone been running R134a with an original RV2 and with the EPR valve installed and still having good luck with it?

As long as you replace the seals with green seals and clean that sucker out good, yes you can reuse it with R134a.  Did you get barrier hoses? 

If you want to stick with R12 you may have a though time finding someone to do it legally but it's easy if you don't care about that part.

I shelved my old RV2 and got a rotary compressor and barrier hoses.  I think I gained about 50 hp removing that old thing.   

[Pete in NH]

Surprisingly there is still a lot of real R-12 around. Most shops don't want to deal with it because they don't want to have two sets of recovery machines and tools around when there is so little call for R-12 anymore other than our old cars. EBay is loaded with real R-12 and it's going for around $20 a can, Which is not much more than R-134A these days. I think when you factor in the cost of doing a proper R-134A conversion that $20 a can is the least expensive way out and the A/C system will work as intended. I got my 609 certification a number of years ago to buy R-12 legally, it's fairly easy to do. If you're interested look up MACS.org, the Mobile Air Conditioning Society.

I can understand why someone might want to convert to R-134A for convenience sake but, you really don't have to unless you live in Canada where R-12 is not legal. On converting to a newer rotary compressor, while the old RV-2 is a bit of a boat anchor it is a really tough compressor. With it's internal oil pump system it will be still chugging along long after the newer aluminum axial compressors have long ago ground themselves into powder.

Years ago I bought my own small vacuum pump and gauge set. The first time I didn't have to pay someone else to work on my A/C it payed for its self. Over the years its payed for its self many times over and I know I've done the job properly without short cuts. And as much as people think it is, A/C systems are not rocket science, especially the old Chrysler systems.

[WH23G3G]

I think when I put the a/c compressor on the engine I put an 8oz bottle of PAG 100, but now it's been so long I don't know if I perhaps put in Ester oil. I haven't run the compressor though. That's mainly what I'm worried about. And I probably didn't get all 8oz in there because I didn't have a small enough funnel to get it in the oil plug hole very easily. I'm pretty sure I installed PAG because I wasn't converting an old system I replaced everything. I bought one new a/c hose from the compressor to the drier and had the other two rebuilt using R134a approved barrier hose. However, I think the shop shortened the large low pressure hose because it pushes down on the distributor cap and wire boots. So I need to find another one. I believe I have the adjustable EPR valve. I remember it having a nut on the back of it. How do you actually adjust it? The only thing I can see is that you can loosen or tighten the nut. I wanted the original look too so I went with the RV2 compressor and where I work we had two in stock so I got it for less than $100. I'm interested in seeing how dramatic the drop in power is on my 400-4. Hopefully it won't be as dramatic as the a/c on my 4 cylinder Ranger that pretty much kills the motor.

[Pete in NH]

The 383 in my 71 doesn't even seem to notice when the clutch on the RV-2 kicks in. On the oil, I was going to suggest Ester based oil as it is compatible with both R-12 and R-134A. That way if you didn't like the way the system performed with R-134A you could easily change to R-12 without having to flush the whole system. Too bad about the line over the distributor being too short, even the stock line makes it a real pain to get the distributor cap on and off.

Yes, it is a real pain to dribble the oil into the RV-2 crankcase with the compressor on the car. Even with a small funnel it takes a while. To check the oil level, look in any Chrysler shop manual covering the RV-2 systems and they will show you how to make up a little drip stick with oil level marks. The system must be discharged of refrigerant to make this measurement.

On the EPR valve, since I'm still running R-12 in my car I've not actually done this adjustment. My understanding is that a quarter turn counterclockwise on the adjustable valves will lower the pressure about 4 LBS down to around 22 LBS. I did quite a bit of reseach on all this back in the 90's when it looked like R-12 was really going to go away. Fortunately, R-12 didn't go away so I never had to convert my system.


Be very carefull about leaving your system open for any length of time as the receiver-driers have a very limited capacity to absorb much water and will readily do so if left open or unsealed.

[WH23G3G]

I have everything bolted up so nothing is left uncapped. I'm amazed at how difficult it is to find a used a/c hose. I guess only the 73-74 b-body big block a/c hoses will work. The small block is the same size but it bends different. I hope that if I don't find one to have re-repaired that someone can make a new one with a better routing.

[PlainfieldCharger]

Here is a link I found on ebay. Not sure if it has the hose your looking for, but has some good pics of what they are selling.. These don't come along very often.

http://www.ebay.com/itm/73-74-75-MOPAR-A-C-LINES-HOSES-A-B-E-BODY-DART-CUDA-CHARGER-CHALLENGER-DUSTER-SE-/350818564838?pt=Vintage_Car_Truck_Parts_Accessories&hash=item51ae6a7ae6&vxp=mtr

[Pete in NH]

On my 71 383 the suction line on the rear of the compressor has a muffler in the line that sits just slightly forward of the distributor cap and has about 3 inches of clearance between the bottom of the muffler and the cap. I don't know if the 73 lines were slightly different. I'm pretty sure small block lines won't work because the compressor mounting location is slightly different. If your current suction line position measures up close to mine that's as good a sit gets with a stock line.

[WH23G3G]

That link is for a Dart 318 line. It's got one of the large hoses I need from the evaporator to the compressor but it won't fit. I know that the hose I got was either cut wrong at the hose shop or it wasn't from a big block Charger. I know it came off of a 73 Charger but don't remember if the guy said it was a 318 or 400. I know the 71-72 b-body hoses routed different so they wouldn't work. I only think a 73-74 b-body would work. Not sure if 75+ would work either. But I have photos of 400-4bbl Charger engine bays and I can tell the way their hoses sits clears the cap a lot better than mine. Mine actually pushes the boot down, so it's actually touching.

[Nacho-RT74]

there are two kinf of suction hose assembly specially on 74s, due an iddler pulley mounted on Compressor bracket ( compressor bracket is diff for these too, for the provision to the pulley). The ones with this pulley, get the reservoir or "muffler" closer to the dist cap.

I' talking about Big Blocks

never have seen those on cars before 73... not even sure if 73s got them