Proper compressor oil to use ?

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   I need to replace the compressor in my 67 DPL. The car is charged with R-12 but the compressor just got very noisy so I want to replace it before it tosses a rod or piston. Is there a specific oil to use with R-12 is or there a "universal" oil that can be used that's compatible with whatever oil may be in the system? I just ordered a repop York from APD. Doug says they've had good luck with them but they take a different type of seal for the Rotolock fittings. I will isolate the rest of the system using the service valves when the time comes to do the swap. Other than pulling and holding a vacuum on the new compressor and topping off the Freon charge once I get the new compressor running is there anything else that I should do ? The system has been working excellent up to this point.  Proper charging pressure on the high side is 2 X ambient + 80, correct ? Looking at the TSM it seems that the low side stays at 20# irrespective of high side pressure. Seems odd to me, but that's what the TSM says.

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
george w Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jan/27/2013 Location: New Jersey Status: Offline Points: 2899	Post Options Post Reply Quote george w Report Post Thanks(0) Quote Reply Topic: Proper compressor oil to use ? Posted: Sep/10/2019 at 7:05pm
	I need to replace the compressor in my 67 DPL. The car is charged with R-12 but the compressor just got very noisy so I want to replace it before it tosses a rod or piston. Is there a specific oil to use with R-12 is or there a "universal" oil that can be used that's compatible with whatever oil may be in the system? I just ordered a repop York from APD. Doug says they've had good luck with them but they take a different type of seal for the Rotolock fittings. I will isolate the rest of the system using the service valves when the time comes to do the swap. Other than pulling and holding a vacuum on the new compressor and topping off the Freon charge once I get the new compressor running is there anything else that I should do ? The system has been working excellent up to this point. Proper charging pressure on the high side is 2 X ambient + 80, correct ? Looking at the TSM it seems that the low side stays at 20# irrespective of high side pressure. Seems odd to me, but that's what the TSM says.
	Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.

6768rogues Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/03/2007 Location: United States Status: Offline Points: 6237	Post Options Post Reply Quote 6768rogues Report Post Thanks(0) Quote Reply Posted: Sep/10/2019 at 11:16pm
	R12 uses mineral oil, not ester or pag. The York has a sump to fill to the proper level. I remember something like removing a plug, putting in oil and using a piece of wire for a dipstick. I use twice ambient plus 80 as an upper level guideline for R134A, R12 should be cold at a lower pressure. I would add a little at a time and watch the pressure while using output temp to see if it is cold. Put a big fan in front of the condenser, close all the vents except one, run the fan on low speed and insert a thermometer in the open vent. Now with a clean compressor it is a good time to convert it to R134A. I have had good luck with it and it is available everywhere. There is a possibility that the failing compressor sent junk through the system. If that happened, it can ruin your new compressor. No way to know except to flush it out or roll the dice. Edited by 6768rogues - Sep/11/2019 at 2:54pm
	Content intended for mature audiences. If you experience nausea or diarrhea, stop reading and seek medical attention. Located usually near Rochester, NY and sometimes central FL.

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Sep/30/2019 at 6:29am
	Polyol Ester Oil (POE -- usually just called "Ester oil" or retrofit oil) is compatible with both R-12 and R-134a. If I were going to continue using R-12 for now I'd use Ester. If you need to switch to R-134a later you wouldn't have any issues. One reason for changing the o-rings and seals when switching to R-134a is that PAG oil (usually used in R-134a systems) attacks older o-rings and seals. It's not the refrigerant that requires the o-rings and seal to be changed, it's the PAG oil. R-134a does need barrier type hoses though, as the molecules are smaller and will slowly seep from the original R-12 hoses. If you've had the hoses replaced in the last 10 years or so they will be barrier hoses, that's the common AC hose now. I don't think you can find the old type anymore, but it's possible...
	Frank Swygert