Mineral oil (R-12) is not compatable with synthetic oils (R-134a). As I posted earlier the R-12 is still around and work the best, AL.

 

what's the price of each these days?

 

If you do a complete flush to get out all the old oil...which I bet, like mine, you have almost a pound in your condenser...AND replace all your seals with the green O-Rings then you will be fine. I did converted my OEM A/C system to R-134a and all I did was replace the POA valve and reservoir unit with a new one that was calibrated for R-134a...all new automotive A/C components, according to the people I bought the POA valve from, are designed and calibrated for R-134a which is supposed to completely replace R12 at some point in time.

Here's what I did:

1. I opened up the system and replaced the POA valve and all the O-Rings with the green ones. I left everything else as is...including the compressor, but I made sure to DISCONNECT THE WIRES FROM THE COMPRESSOR CLUTCH.
2. With the system still open I drove the car to a shop and had them flush the system...the mechanic said I had at least 1 pound (yeah...pound not ounce) of R12 oil in my condenser.
3. I drove the car back to my garage and poured about 4 oz. of liquid POE (ester oil which is compatible with the original R12 system) directly into the compressor...until it was full. I then reconnected all the lines and made sure everything was sealed.
4. I then drove the car back to the shop and they evacuated the system and checked it for leaks...it was perfect.
5. I then bought 4 11oz. cans of R-134a which included 2oz. of oil in each can. I drove home and connected the first can to the inlet fitting on the compressor. I started up the car and turned the A/C system on max then went around and plugged in the wire to the compressor clutch.

The first can of refrigerant got sucked in right away....perhaps in as little as 5 seconds. The second can took longer...about 1 minute. The 3rd can took almost 5 minutes to drain. I still had about 1/2 of the 4th can left after leaving it on their for 10 minutes.

The effect was air vent temps as low as 40ºF, but the evaporator outlet tube was getting frosty. I later discovered that almost 1/2 of my evaporator core was covered with leaves.

Another upgrade is a new OEM style motor and rerouting the voltage source from the ignition circuit which is at about 11.5V over to the output of the alternator which is at about 13.5V. These two upgrades will give you almost twice the ouput at the vents.

Also keep in mind that it's not how much vacuum you put on the system as much as how long you keep the vacuum on it. Even 6 inHG of vacuum will work if you leave it on the system overnight. But, 16 inHG or more just requires like 2 hours before you can be assured that all the system is properly evacuated.

Keep us posted.

 

That should be a sticky too...

 

Pulling a deep vacuum is a must. It should be past 29" and ideally measured with a thermister vacuum gauge so it will hold at least 700 microns for at least 3 minutes so that all residual moisture will boil off. The moisture left in a system will turn into acid and potentially ruin valves and compressors. That it why you should also change the drier whenever a system is opened.

Hee is a list of recommended oils for common compressors. Viscosity is important

Behr/Bosch rotary compressors - Ester 100;
Behr/Bosch piston compressors - PAG 46;
Calsonic V5 - PAG 150;
Calsonic V6 - PAG 46;
Diesel/Kiki (Zexel) DKS, DKV & DCW - PAG 46;
Hitachi (all) - PAG 46;
Keihin (all) - PAG 46;
Matsu****a (all) - Ester 100;
Mitsubishi FX80 - PAG 100;
Mitsubishi FX105 - PAG 46;
Nihon (all) - Ester 100;
Nippondenso 6P, 10P, 10PA, 10P08E - PAG 46;
Nippondenso SP127, SP134 and 6E171 - PAG 46;
Nippondenso TV series - PAG 125;
Panasonic (all) - PAG 46;
Sanden SD500 and SD700 - PAG 100;
Sanden SD710, SDB, TV and TRS - PAG 46; and
Seik-Seiki (all) - Ester 100.

Here is a link to the vacuum chart

http://www.actoolsource.com/vacuum_in_microns_chart.pdf

 

Nooner - What if someone is using an oil that works for a R12, and not 134A but isn't designed for the compressor being used?

 

You should alsways use the oil that is recommended for the specific compressor and refrigerant.

Generally mineral for r12 and pag or ester for 134a

Here is a better link

http://www.tirechanger.com/rti/OilCh...0with%20r12%22

 

Great link...thanks.

 

If you want to mess up a garage, blow 150psi through a old condensor coil that you think doesn't have any oil in it. A ounce of oil may as well be a gallon when its running down the walls.

 

So what your saying is that if I decide to give up on R134 and revert back to R12 I'm going to have to go through this whole process again with the oil?

 

That's true. It's also against federal law to switch back.

Yo may want to look into something like freeze12, a lot like r12 but a lot cheaper. A/c professionals don't like it, but a lot of diy'ers use it.

 

You said you have all the equipment you need to properly do this yourself? I would suggest 134A. It's legal to do. You know you need to clean the system, and use a new oil designed for the 134A. You also know what components need to be replaced for the switch, and you know that all your I's need to be crossed, and T's dotted. You do a switch to 134A the right way first, and you will enjoy 40 degree air from the vents. Also change to a better blower as suggested in a post above.

 

$15.00-$20.00 a piece, AL.

 

I lucked out, my gf's mom gave me a 50lb. can about 3/4 full fo R12 and a set of guages that was her dad's before he died. I have mine blowing icy cold now!

 

Lucky duck...

 

That only happens in the movies.

 

I guess not if he has around 35lbs of R12. That's enough to do my girlfriend's car 15 times.