AC experts-more questions

rfuerst911sc · 01-03-2005, 01:18 PM

I am updating my ac on my 83SC,the car has a Sanden compressor.I have removed all the rubber hoses,receiver drier and evaporator box.I am replacing all the rubber lines with new barrier type,the receiver drier and the expansion valve.I have added a underbelly condensor and will be adding a small fan assisted condensor in the rear fender(12x14x1.5).My question is how much oil should I add to the system?I am assuming I have lost oil that was in the hoses and I am adding condensor capacity,however I have not drained the compressor.If I go with R134A then I will drain the compressor because I will have to change the oil type,if I go that route how much oil should I add?If I go with R134A do I use PAG or Ester?If I stay R12 what type of mineral oil do I use?Thanks.........Rick

dmarv · 01-03-2005, 02:12 PM

If you stay with R-12, there is only one mineral oil to use. R-12 can also use Ester, which is compatible with R-12 and R-134a. If you switch to R-134a use PAG. PAG comes in different weights and is a better oil in a R-134a system that has all new components. If you use PAG you may need to flush out the compressor using a A/C flush. As far as how much, I will need to look it up. I would drain the compressor into a measuring cup. Then add that amount of new oil plus a tad to the compressor. That would get you close for the compressor oil but you would still need to know how much for the system.

DonMo · DonMo's Garage

Did you flush the compresser, condensers and evaporator? They will need to be if you swap referigant.

I did a hose job, new Seltec (sanden type) compresser, dryer, evaporator and extra front fender condenser and put in 8-10oz of ester oil. Spread it around if you can otherwise you are charging your system and have to push the oil.You can go either way with ester and I first flushed my system components (except dryer) with 100% mineral oil and used my air compressor to blow it clean. From thereI pulled a 24 hr vaccum, then charged with R12( I had a bunch left over by luck).

88911coupe · 01-03-2005, 02:22 PM

Can you post some details on the underbelly condensor...size, price, where sourced, how you installed it, etc.
TIA,

dmarv · 01-03-2005, 02:42 PM

I just looked up a 1986 Porsche 911 using R-12 refigerant and it says to use 38oz of R-12, which would be about 8oz to 10oz of oil.

rfuerst911sc · 01-03-2005, 05:22 PM

Thanks everyone.No I have not flushed the evaporator,underbelly condensor or the front condensor but I plan to.The condensor I am adding in the rear wheelwell will be a brand new unit so that won't be flushed.It appears if I go with R134A I can use either PAG or Ester?I have 2 cans of PAG oil,one is viscosity ISO 150 and the other is ISO 100,on the can of ISO 100 it says it is for Sanden compressors along with 3 other brands so I am assuming because I have a Sanden that the ISO 100 is the correct weight?In regards to flushing I have seen in my local PEP Boys that they sell a flushing compound,is that the best stuff to use?Another question,if I go R134A and it seems like that's the direction I am going when I install the R134A adapters on the compressor do I remove the Schrader valves before installing the adapters?Thanks again.

DonMo · DonMo's Garage

You may want to consider Freeze 12 or Duracool as alternates, use the search button. Lots of info.

Hugh R · 01-03-2005, 05:42 PM

Do a search on Jim Sims on this site and you'll find everything you want to know. I used denatured alcohol to flush my condensors when they were out of the car. Evaporates completely, no residue, and drives out water. About 6 ounces of oil is right for a Sanden compressor. I unscrewed the schrader valves and replaced with the 134A valves, but they make both types one that goes on top of the old schrader (you take that needle valve out I believe, and the other type. In converting from R12 to 134A its one of those two oils, but I don't remember which one.