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134A BACK 2 R12?

jrm-76nova on Thu June 24, 2010 11:58 PM User is offline

Year: 76
Make: CHEVY
Model: NOVA
Engine Size: SB 400
Refrigerant Type: R12
Country of Origin: United States

don't KNOW MUCH ABOUT AC BUT RECENTLY DECIDED IT WAS 2 HOT TO ENJOY THE WEEK END RIDE. GOT A NEW COMPRESSOR FROM OREILLY . RETRO FIT IT FOR 134 BUT IT JUST didn't BLOW THAT COLD. SO I DECIDED TO GO WITH R12 . DO I NEED TO DO ANY THING OTHER THAN DRAIN AND FILL?

Edited: Fri June 25, 2010 at 12:42 AM by jrm-76nova

newton5 on Sun June 27, 2010 2:38 AM User is offlineView users profile

If your system is original except for the compressor, you certainly need to do much more than "drain and fill at this point. Resurrecting a "dead" AC system can get costly.

All of the seals in that system are 34 years old, as are the rubber hoses.Would you rely on 34 year old rubber engine belts or tires?
It's "possible" that your old hoses are ok, I've seen many on systems of that vintage that are good (for the time being). It's a judgment call that can bite you later, so I recommend having the hose sets rebuilt.

Your original refrigerant went somewhere, via a leak. Converting to R134a doesn't magically repair leaks. Leaks don't become smaller over time.

The main wear item in your system, the receiver/dryer is also more than 25 years overdue for replacement. Equate it to your engine oil filter. Would you change your oil without changing the filter for 25 years? Your original R/D desiccant also isn't compatible with R34a. At this point, it's done.

Your O'Reilys retrofit "death kit" added about 12 oz of Ester oil to the system along with the original ~12 ounces of Mineral oil to create a "soup" of incompatible oils that don't do much lubricating of the compressor and are taking up a lot of real estate in the system. To make the system work properly, you need to flush that mess out.

In addition, your system likely has a POA valve that is not calibrated for R134a. You may have what is called a VIR (valves in receiver) on your 73 instead of a separate POA valve.


You've spent the bulk of the money (on the compressor) to repair the system. Take some time to become familiar with properly repairing AC systems by browsing the forum and the FAQ section before you attempt to further "fix" your system.

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