66 Monaco Wagon A/C Resurrection

[TxDon]

Spring is officially here so I need to get serious about fixing my A/c system before Texas summer gets here too soon. If you have followed my project thread (66 Monaco Wagon Preservation) I bought this car with a non-cooling but still sealed system supposedly converted to R134 but without the correct charge valves etc. I took a chance and pumped it up with more R134 and some oil and it actually cooled quite well for about a month - then the compressor failed. Knowing a rebuild is needed I have researched threads here plus a bunch of internet sites and I have bought most of the A/c tools, now I need to make a real plan and get going. To start here are some basic questions:

• My car has the optional dual system with a second evaporator and fans hanging from the roof and all lines tee into the underhood lines. If anyone has worked on this same system I'd like to hear from you.
• There seems to be two camps on underhood rebuilds, the leave-it-stock approach and the replace-everything-Sanden-compressor approach. I would prefer the stock approach but I'm not totally locked in.
• I need my car to be driveable through most of the process so I need to leave the old compressor in place or use a readily available pulley replacement setup.
• I have never done flushing of A/C components and could use advice on equipment, technique, etc.

I know a lot of you have already done this successfully and I hope I can benefit from your experiences, thanks in advance.

 

[Davea Lux]

First off, if you do not know for sure the system was properly converted to R-134a from R-12, you have a problem. The oil in an R-12 system all has to be removed completely before any conversion work is done. Usually this is done by evacuating the system for several hours to evaporate as much oil as possible and then the system is flushed with dry nitrogen to purge any remaining R-12 oil. If this was not done, the R-12 oil turns into something approaching gorilla snot when exposed to R-134a. This nasty mess can not be removed by nitrogen purging or evacuation. That mess will need to have the evaporators and condensers removed and solvent flushed. That should be done to the condenser after a compressor burnout to remove any metal shavings from the compressor failure in any case. A properly converted system would have Pag oil installed before the system was re-charged. The Pag oil has a dispersant in it which keeps any remaining R-12 oil form clumping or solidifying. Your compressor most likely failed because it was starved for lubricant. This happens a lot with RV2 series compressors because the smaller R-134a molecule does circulate oil nearly as well as R-12, the oil tends to collect in the bottom of the condenser, the filter dryer and the evaporators and if the gas charge is at all low, the oil will stay there and the compressor will die.

The second issue is that all of the existing black o-rings in the R-12 system have to be replaced with the R-134a units which are green in color. These are a high density rubber compound that is designed for the smaller gas molecule of R-134a. The suction or low side hoses should also be replaced with the more modern high density hose as the old R-12 hoses will leak R-134a thru the inner hose liner and from the hook type fittings on the ends that pierce the inner membrane. Be sure not to reuse the hook type fittings.

Once the system is properly cleaned up, the filter dryer needs to be replaced, the low pressure switch needs to be replaced and the system evacuated. I would suggest adding about an extra 2 oz of Pag oil over what the FSM suggests for your system. This gives a little added protection and will not hurt anything.

A lot of RV2 series compressors failed shortly after the conversion process and unless the converted system is closely monitored for the state of the charge, repeated compressor failures are likely. That is why the rotary Sanden compressor is a popular alternative as it is not nearly as oil dependent as the RV2 reciprocating unit. There are a number of threads on this site about converting to the Sanden compressor, I would suggest exploring that alternative before making a final decision. Good Luck.

Dave

 

[TxDon]

Thanks Dave. All I know about the car's previous life is per discussion with the PO but I tend to believe him as everything else he said about the car has turned out to be true. He did the R134 conversion 6 years ago which included evacuation, addition of PAG oil, and R134 charge, not sure about flushing. The system worked well for him for two years then the car was stored and not used until he sold it. When I checked it the system still had about 1/2 charge so I charged it and added a bit more PAG. In the few times I used it before the compressor failure both the front and rear units worked and cooled very well. Based on this performance I doubt the snot clog scenario exists but it does seem like the oil drain out you describe due to low charge is what did the compressor in.

My tentative plan was to flush out the condenser to see how much contamination I find, most sources say that the filter dryer would stop most of that from circulating beyond it. There seems to be a lot of conflicting opinion on flushing of other components.

 

[Davea Lux]

Thanks Dave. All I know about the car's previous life is per discussion with the PO but I tend to believe him as everything else he said about the car has turned out to be true. He did the R134 conversion 6 years ago which included evacuation, addition of PAG oil, and R134 charge, not sure about flushing. The system worked well for him for two years then the car was stored and not used until he sold it. When I checked it the system still had about 1/2 charge so I charged it and added a bit more PAG. In the few times I used it before the compressor failure both the front and rear units worked and cooled very well. Based on this performance I doubt the snot clog scenario exists but it does seem like the oil drain out you describe due to low charge is what did the compressor in.

My tentative plan was to flush out the condenser to see how much contamination I find, most sources say that the filter dryer would stop most of that from circulating beyond it. There seems to be a lot of conflicting opinion on flushing of other components.

It sounds like, since it worked for two years, that you probably do not have an oil breakdown problem. Pull the condenser and have it cleaned. Replace the filter dryer and low pressure switch. You are correct that the filter dryer will stop most of the metal particles from getting into the rest of the system. The stuff that gets past the filter dryer is likely too small to cause any major problem most of the time. The high side line from the compressor to the condenser will likely be full of metal also so clean or replace that as well. Flushing the other components is a must on systems that were left open to atmosphere for an extended time or if the oil has snotted up. Otherwise it is probably not going to be necessary in most cases. Be careful with the fittings on the condenser as these are often seized and you can break the lines, spray them with a good penetrating lubricant. If that does not work, apply some moderate heat to the fitting. The same holds true for any fitting where you need to replace o-rings.

Dave

 

[TxDon]

I do hope I can keep this simple. The line from the compressor to the condenser has a muffler in it and I've read they cannot be successfully flushed, is that true?

 

[TxDon]

pics

 

[Davea Lux]

I do hope I can keep this simple. The line from the compressor to the condenser has a muffler in it and I've read they cannot be successfully flushed, is that true?

The muffler can be discarded when you do the hose update as it is not needed with R-134a. Its primary purpose was to prevent liquid refrigerant from entering the compressor and causing the pistons in the compressor to "hammer". The R-134a is a lighter and more volatile refrigerant and won't cause a problem with liquid intrusion. If you are worried about maintaining a stock appearance, then the muffler should be replaced.

Dave

 

[TxDon]

The muffler can be discarded when you do the hose update as it is not needed with R-134a. Its primary purpose was to prevent liquid refrigerant from entering the compressor and causing the pistons in the compressor to "hammer". The R-134a is a lighter and more volatile refrigerant and won't cause a problem with liquid intrusion. If you are worried about maintaining a stock appearance, then the muffler should be replaced.

Dave

are metal lines like the one with the muffler available or reproduced for C body cars?

 

[Davea Lux]

are metal lines like the one with the muffler available or reproduced for C body cars?

No reproduction. There is another thread someplace on this forum about the fittings to get rid of the muffler. I think it might have been from Commando, but not sure.
www.classicautoair.com might have a new replacement.
Dave

 

[TxDon]

Thanks, tried to look up stuff at CAA but their online catalog is messed up.

 

[TxDon]

I've been searching and re-reading A/C threads here and it sure seems like keeping the RV-2 is not too popular. Who out there is happy with an R134 converted RV-2?

 

[Polara_500]

Mine seems okay, converted about 15 years ago, then it all leaked out over about 4 years - since I wasn't driving it much I didn't worry about it. A couple years ago I had him recharge it and it seems to work fine so far.

 

[Davea Lux]

The RV2 was a bomb proof compressor on R-12. Not so good of R-134a because of the previously mentioned oil starvation issues. You could drive to Mexico some weekend as they still have not banned R-12, you could get it recharged if you are someplace close to the border..

Dave

 

[lemondana]

Go back to R12! If you look around hard enough you can find some. Here in Nebraska, about every swap meet I see some. I used to buy it when I could afford it. I had a counter person in a new Napa store last year tell me that they had R12 to sell again. I've seen too many R134 conversions gone bad with the RV2 compressor.

 

[Dsertdog]

Following...

 

[TxDon]

Thanks but I'm not going back to R-12 since it sounds like even R134 has a shelf life. Part of the RV-2 question is due to what I'm reading about crappy rebuilds and apparently only 4Seasons owns the business.

 

[Polara_500]

Hmmm, now that you mention that the ol' brain is kicking in a bit. The year after I converted to 134 when I was down in OK in July the RV2 compressor died on me. Long story, but lots of luck and helpful folks down there I got a reman compressor from a local parts house, replaced it under a shade tree in front of a mechanic's shop using only my small traveling tool box, the shop did make time to evacuate and recharge the system and then it held for about 4 years then got ignored until I had it recharged a couple years ago. So at one time, quality remans were still available - wasn't on the shelf at the parts house in Norman, OK, but they had it the next day for me. And all was well as I spent the next two weeks cruising around west TX, would have been a lot different without A/C.

 

[Davea Lux]

If you are looking for a permanent solution that will give you reliable A/C, you need to convert to the Sanden compressor and do the hose and other upgrades previously noted. Your dual evaporator system is an accident waiting to happen with the RV2 compressor on R-134a, too many places for oil to collect and stop circulating. The next best alternative would be to replace the RV2 with a reman unit and recharge with R-12, it will function reliably with that refrigerant. A lot of the bad rap on 4 Seasons rebuilds is because of the oil starvation problems inherent with R-134a. Yes they do screw up some of the rebuilt units, but so does anyone else who does that type of work.

Dave

 

[TxDon]

I may be starting to lean toward the Sanden route...

 

[TxDon]

Thanks to the responses here and many past threads on this subject I've decided to with the Sanden compressor / underhood line conversion rather than try to keep the RV-2. One thread by John @live4theking impressed me with his conversion - Converting from RV-2 to Sanden
He used the BPE mounting brackets and bought everything else separately. What are the advantages or disadvantages of doing this versus buying a full BPE conversion kit?