Hi all,

My 1984SE is still blowing cold air with Freon 12 but am anticipating that sometime in the future may need to convert to R134 and was wondering the specifics of drawing a vacuum on the system. What does one use and where is it connected? Also, what happens if it is not done at all?

TIA

pmartin

 

When you're ready, go down and have it done professionally. It will run about a 100 dollars for the fittings and the labor. You need to have the system evacuated. Then flushed with solvent to remove traces of R-12 and it's lubricant. Then you have to pressure test and recharge and add the new lubruicant. Oh, you also have to replace your old seals with new ones. They aren't expensive and take only about an hour to replace them all. 30 minuites if you're good.

R-12 and it's lubricant react with air. If there are traces it will become caustic when it is mixed with r134a and eat your seals out.

Also, if there is any air in the system, your lubircant won't flow and the compressure will overheat.

The guy I had do it charged me 117 dollars total for all the work and the lubricant and the R134a.

 

Spieder,

If I could have it done for about $100 that would be great but went to 2 shops here and was quoted $250 at one and $400 at the other.

pmartin

 

ok call me getto or call me epa natzi but this works great. i have a old compressor hooked up to a 120 volt a/c motor on a little cart... hook it up to the guages and plug it in i get 27 lbs vac. and its FREE then change to the new oil, slap on the new fittings and refill... has worked GREAT on 7 cars this year alone

 

BA,

I haven't done this before so have some questions. What kind of "old compressor" is it? I am assuming you connect to the gage manifold in such a way as to not lose vacuum when disconnected. You then said you change to the new oil. How do you do that and not lose the vacuum? Hope these questions make sense.

pmartin

 

Good lord, why 250?

I even got a quote from PepBoys (end all be all of rapping the customer) and they were 160 dollars for everything and it included labor.

 

its a old a/c compressor from a toyota... we welded the clutch in the ON/ ingaged position and then put a a/c motor with a v belt pully on it... spread them till its tight and u got a vacume pump.... yes you loose the vac. when you install the oil and the new fittings but then you do it again.. shoot in a little 134 and vac. it down again and then fill her up and enjoy the cold a/c

 

Considering that absolute atmospheric pressure is 14.696 psi at sea level, it isn't possible to draw 27 psi vacuum. The lowest you could go is to absolute vacuum right....Zero....therefore the highest vacuum pressure you could draw is 14.7....which is really hard to do. The condensor at my plant draws 1 inch mercury at full power, which is about 0.5 lb absolute pressure, or 14 pounds vacuum.

 

However, his AC is cold, regardless, so this point is irrelevant in the context of this thread....this old, old thread from the dead...