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How much and which oil to use when retrofitti ng

dan116 on Fri May 30, 2008 3:56 PM User is offline

Year: 1990
Make: mazda
Model: 929
Engine Size: 3.0
Refrigerant Type: r-12
Ambient Temp: 95
Pressure Low: 41
Pressure High: 240
Country of Origin: United States

How much and which oil (PAG or POE) to add when converting a 1990 Mazda 929 from R-!2 to R-134a. I am replacing the receiver/drier, pressure switch and o rings lubricated with NYLOG. I will flush the Condenser and lines with Hecat safe flush. If the old mineral oil is clean I will not flush the evaporator. The expansion valve is built in to the evaporator case and is a major, major job to remove and re-install. My repair Manuel says to add 60 cc to the compressor 30cc to the condenser and 10cc to the receiver/drier when replacing them. Is that all the (PAG or POE) oil I add or do I add the Total system amount of oil (8 OZ) because R-134A does not mix with the reaming mineral oil?


mk378 on Fri May 30, 2008 4:11 PM User is offline

This system is running with R-12 now? If so why convert?

Anyway to convert use a POE oil such as the BAV Auto Ester 100.

Take the compressor off of the car and drain it. I think it will have a drain plug in the side. You want to get as much of the old oil out as you can. Flush some new ester oil thru it then drain and discard that mixture (Never put solvent into a compressor, only new oil). Put the full 8 oz of new oil into the system.

I think the evaporator case can be removed rather simply by taking the glove box out of the car, then unbolt the case, disconnect the lines under the hood and pull it out. If that's the case you should do it because usually there's a lot of dirt and leaves in the air passages that will hinder performance. Do not try to flush thru the expansion valve. If you want to flush the evaporator, the case has to come out to disconnect the valve.

dan116 on Fri May 30, 2008 5:32 PM User is offline

I have a small leak of R-12, less than 13oz. In 4 months. I will have to open the system to repair the leak. I used hotshot 414b last season; it is time to convert to the easy to find R-134a. I will probably replace the expansion vale and flush the evaporator as you suggested. Thanks for the information to use POE and to put system capcity 8oz in if I don’t flush the evaporator.


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