Make: Rolls Royce
Model: Silver Shadow Mk1
Country of Origin: United Kingdom
Hi I wonder if you can give me the best advice on how to convert the AC to R134a . The R12 worked fine until a hose came loose and all the R12 has slowly leaked away. I have all the equipment to do R134a Cars except any flushing gear. I know the oil does not mix and need to know what is the best way to deal with this and think I have read you can add another oil that will let the two oils mix ? I also know the seals should be green but have also read that this is not always required ? I will order the r12 to r134a adaptors to start with and the other parts that you advise me to replace . Does the RR SS MK1 have a HIGH PRESSURE SWITCH ? , If not what do I need to add one ? I will replace the drier and as I say have all tool except any flushing equipment . Thanks for all your help David
ps the compressor is easy to remove so easy to drain the oil from this and refill with pag if possible but expect some oil will be in evap and condenser etc
First of all , what brand of compressor are you dealing with ?
Only retrofit I have worked on , it was suggested to use POE ester oil ?
The compressor had not self destructed , so I was not dealing with the metal particles in the system .
I used compressed air to plow the oil out of the system & then replaced the accumulator O-rings from lines to compressor & compressor shaft seal .
Minimum requirements for converting a system to R134a.
If system has any refrigerant R12 left in the system it must be reclaimed by an approved recovery machine.
Accumulator/drier must be replaced with an R134a compatible replacement. Conversion fittings and label must be added to the system. Label should have the amount of R134a used and quantity and oil type listed. If vehicle is not equipped with a high pressure cut off switch it must be added. That is the required minimum! While complying with the EPA laws may not provide the best performance.
Flushing the system to remove the mineral oil and debris should also be done. R134a and mineral oil do not work well together so leaving it in the system with R134a is not recommended! O-rings should be replaced with either NBR or HNBR replacements. Adjustment of the pressure cycling switch may also be needed to achieve the best performance. In some cases an upgrade of the condenser may be required to achieve the original performance. In many cases the parallel flow condenser will not be available as a direct replacement. Using a universal parallel flow is an option. A new custom hose set would be needed for the different style fittings used on the various parallel flow condensers.
There are many different suggestions when charging a R12 system with R134a. System must be evacuated before starting the charging procedure. I suggest you start with about 70 percent of the original R12 charge and add an ounce at a time until vent and pressure readings reach the best available results. Remember it is easy to over charge a system with R134a so patience is important.
The compressor is a Frigidaire code 122012 Model 5910448
This is a friends car in our Jaguar car club so have not looked at a RR car before. I would need to check if it has a OT or Expansion Valve as i do not know but think all the cars i have seen the cheaper cars have a OT and more expensive cars have TXV , is that what you have found ?
If i were to vac out charge with R134A and then do a RAPID RECOVERY via the HP port would that not pull out the oil ? This would pull a fair amount of PAG but i wondered if the mineral oil would still get pushed out . I expect this would take a few cycles like this but have not heard of any one doing it this way as i expect it would take longer , but would it work ? I would remove the compressor first and empty that and refit to remove the most oil to start with . Does the compressor info mean any thing ? AC system has no known faults as it has just lost the R12 due to the loose hose joint.
Thanks for all your help . Does Ester oil mix with the mineral and then ok with R134a ?
The 2002 or 2004 Century we had , the OT was behind the vacuum brake booster . Very big pain .
The fittings may be / probably are metric . Not " inch " ?
No idea about that brand of compressor . :-(
I have only worked on GM R4 & V5 compressors .
Do not know about the method of removing / purging oil ?
Best I could figure out , POE ester oil may / probably is more compatible with the old mineral oil , compared to PAG oil ? How much mineral oil will POE & R134a tolerate ? Never got a very straight answer to that question ? So , my GUESS is remove as much mineral oil as you can ?
The only expansion valve system I ever worked on was after market air on my 1966 Mercury Comet 289 cubic inch , when I was a teenager . I replaced the expansion valve & recharged it until the sight glass cleared of bubbles .
I've read that POE oil will absorb at least small amounts of mineral oil like a sponge.
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