cublex

Can the R134 refrigerant be used in a 1974 Cutlass Supreme

fleming442

You need to completely evacuate, flush, then change valves.

bw1339

And adjust the POA valve.

cublex

You what you are saying is I can't just use on of the those AC Pro cans and charge my system...I am really not smart at all when it comes to AC

fleming442

No, that wouldn't be a good idea. Your system requires R12 from the factory. It's still around if you look, and it worked better than R134.

dc2x4drvr

Nope, your car is/was charged with R-12, read what Fleming said ^^^, R-12 & R-134 don’t play well together.

ELY442

I dont know if this is true but someone told me that the R-12 oil is different than the 134a oil and you have to change the condenser because the tubes are larger and the 134a needs to be cooled more than the R-12.

Fun71

Yes, that is correct, the oils are not compatible.

The condenser does not HAVE to be replaced. R134A is not as efficient as R12 so changing the condenser to a modern style for better heat dissipation will increase the system's efficiency so it cools better.

dc2x4drvr

I wish we had a dedicated spot just for our A/C to many threads get mixed up, and members lose out on good info..

olds 307 and 403

You can get away with evacuating the system and changing the valves and oil. We did it all the time years back in the shop but that was mostly with the later R4 compressors. Can you get the little R12 cans?

fleming442

This board already has 40,000 subforums. Sure, add AC for every one!

cublex

I was able to get temp down to about 60 at vent..is that good

Fun71

Depends upon the outside air temp. When it's 115+ outside, the vent temp on my newer vehicle is around 50-60, but when it's only 80-90 outside, the vent temp is below 40.

edit: The above is with a R134A system, not R12.

dc2x4drvr

I saw 32* air at the center vent with 85* ambient until the R-12 leaked out.

bw1339

What are the high and low pressures? And the ambient temperature?

Did your system hold vacuum before charging?

dc2x4drvr

Question, did you add R-12 to get the temp down to 60*, or…?

therobski

To add to Lance, I just discovered a leak in the discharge line in the all original GM A/C unit on my 63 Starfire. Prior, it was nice and cold ( very cold ) I had a local company here in Dallas rebuild the hose and I have reinstalled it on this time capsule car. I'm waiting for spot at my buddy's shop to recharge the system.

edzolz

If you have never been schooled in re-filling the ac system, I would take it to an AC shop. Doing that without proper knowledge and equipment can be very dangerous. You can explode your system as well as back pressuring the can and blowing it up.

therobski

X2 Ed totally agree. That why I'm going to my buddy's shop!!!