[jamesbond]

I posted a question a short while back about retrofit from r-12 to r-134a. Since then I've noticed more issues with my a/c system which caused me to decide to replace much of the system (compressor, hoses, and evaperator core). The only component I didn't replace was the condenser. Anyway I got all of the parts new from Napa. They have r-12 fittings on them. Therefore, I also bought a retrofit kit from Napa. However, I'm concerned from what I've heard from some of y'all that the hoses and compressor may not be compatable with the r-134a. This thought is in reference to the statement on a previous thread by somebody about NOS (New Old Stock). Anyway, please help... for I am planning on putting it back together tommorow and hope this new equipment will work as the guy at Napa said it would.

 

[sle2115]

I would have to wonder as well. The oil used in R12 soaks into the rubber and stops R134a from escaping. If you are using new hoses that are not designed for R134a, I would say it would leak. On the other hand, you might be able to get R12 or one if it's replacements.

 

[Birken Vogt]

The dire predictions about R134 leaking through hoses were found to not really be true but all AC systems leak to one degree or another so often the hoses of an old system got blamed. I would not worry about it.

Birken

 

[sle2115]

[ QUOTE ]
The dire predictions about R134 leaking through hoses were found to not really be true but all AC systems leak to one degree or another so often the hoses of an old system got blamed. I would not worry about it.

Birken

[/ QUOTE ]

The predictions were found to be true in hoses that had been used with R12, not new ones. Again, this comes from three different techs from three different companies.

 

[jamesbond]

OK I gotter dun. I installed all the parts and it seems to work pretty well. Before I did this however I did some research on the material that the hoses were made of. They seemed to check out fine for 134a. I couldn't verify however that the compressor was 134a compatible but the Napa fella assured me it was. Anyway, I got it all put back together. I replaced everything but the condenser which I cleaned using flush from Napa and an air compressor. I was careful to replace all of the o-rings and then evacuated it overnight. It held approx. 30"Hg. I put in 40oz. of refrigerent and about 9-10oz. of ester oil (I found out later that PAG oil might be better but oh well). At an idle the low side was hovering around 35-45 psi and the high side was between 200-250 psi. These numbers were dependent of course on engine rpm and whether it was simply at an idle after start-up or if I just took it off the road. The temperature at the vent was 55-60 degrees F at an idle and 48-50 on the road (70mph/2500rpm). I'm not quite sure if these numbers are acceptable but so far it seems like success to me.

 

[444-4D]

[ QUOTE ]
I found out later that PAG oil might be better but oh well.

[/ QUOTE ]

Don't have any regrets about using Ester(POE)oil. That's what I would have used. I have been told by some very knowledgeable people who were involved with the mfg of both PAG and POE oil that POE is the better lubricant. I don't think your compressor will know which one you put in there.

 

[jjames]

I have been running the R-134 conversion for about 5 years now with excellent results and NO leaks. Yes the leakage through the hoses is true and yes re-using OLD R-12 hoses are better because the leakage on previously run R-12 hoses is virtually ZERO!!. Due to the R-12/oil saturation which tightens the molecular structure/integrity of the hose therefore eliminating the seepage of the R-134 molecule which is much smaller than the R-12. WHew!! OK Chemistry lesson over for now. Enjoy your Cold air and Yes those numbers are very acceptable. I hope your as happy with your R-134 conversion as I am with mine. BTW, I put in all new components except the condensor just like you did. Excellent cooling.

 

[twelve0six]

I'd give it some more refridgerant...Bring it up to around 300 psi high side, and that should bring your cool air temp to around 40...my Turbo Diesel's AC must still be factory R12 because it runs 34 degree's...Most of the time I run my temp control knob in the middle and its just right, even on the 100 degree days we were having.

Shawn

 

[Birken Vogt]

I agree that the temperature seems high but be extremely careful with adding more, it is hard to get it right that way with R134. Whenever I do any work on AC systems I make sure the temperature outside is at least 90 degrees. Run the engine at about 1700 RPM, fan on high, recirculate AC, drivers side window down about 4", temperature gauge in a register near the evap, bulb not touching anything. It is important to get all these things right otherwise results will be inaccurate.

Also was the orifice tube changed. If not then temperatures will not get as low either.

Especially on these CCOT systems, I do not even look at the pressures/temperatures at idle. They just don't mean very much.

Birken