Fast forward to 2025 and the car is almost fully restored including body, paint, and interior. Time for the next project. 

The compressor was rebuilt by a gentleman famous for rebuilding Corvette A6 compressors. Below is all the rust he found in the compressor upon disassembly, and then the after picture. The compressor looks 100% correct.

The receiver dryer was the next to be removed because there was a long lead time for restoration. I had purchased a universal replacement at one time, but I didn't like how incorrect it looked. There are no dryers sold that look correct to this style. Old Air Products in Fort Worth was able to put new desiccant and rehab my dryer to new, including a new sight glass. Below, the original and universal, and the restored original. 

The next step of the restoration was the removal and rehabilitation of the condenser. Many hours were spent straightening the aluminum fins. It was flushed four times with Four Seasons Super Flush solvent, shown below. The first flushes contained rust and rusty particles. It was flushed until clear. The side caps were removed, and the whole unit was cleaned and painted with Eastwood Radiator Paint for the proper look and to maintain proper airflow vs. regular thicker paint.

Removal and restoration of the STV was next. I would not have removed the STV had I not found rust in the condenser. I knew the STV had to come off for a proper evaporator flush. I had tried to remove the STV 20 years ago when I put a new seal in it, and couldn't get it to budge. Fast forward 20 years, and I had tools with exceptional leverage. Below was the setup I used.

As I removed the STV to evaporator fitting, it took some effort to give, and as I continued unscrewing it, there was abnormal resistance. Once I got the fitting out, it was evident what had happened. Either 61 years ago it was installed cross-threaded, or more than likely galvanic corrosion made the steel fitting and aluminum threads to become one. The very first threads on the male side were semi-obliterated, shown below at left, and this caused the flattening of all threads on the STV as it was removed. Note on the right picture the bottom threads as they should be, and the top threads that are flattened beyond repair.

The plan was to send off the STV to The Part Guy LLC to get a new seal in it and to refurbish the original expansion valve at the same time. I tried the forums first, but no one had an STV off a big car. Riviera STVs work backwards. There were none on eBay. With the threads trashed on the STV, I could even run one of the STV eliminator kits. I reached out to James at Best Offer Counts, and he had one just coming into stock off a parts car. Below, that STV and the expansion valve were sent to The Part Guy LLC for rebuilding.

Below are the parts as returned from the Part Guy. 

The next step was to see if I could repair the threads on the evaporator male brass fitting to save buying a $350 replacement in 2025 dollars. I found an $86 thread chaser kit came into existence from FJC, called their Standard Thread Chaser Set 2754. Using the 1 1/16 thread chaser, I was able to restore the fitting, below.




Once the fitting was fixed, the evaporator got the same flushing routine as the condenser, with the addition of making sure the oil bleed line was flushed as well.

I tried to flush the muffler multiple times thinking I could solve the issue with money by using a ton of Super Flush. I had to come to the realization that because the inside of the muffler was uncoated steel, the muffler would just rust again after a flush. Fun fact, the only other non-aluminum parts in the A/C system are the cast iron block and heads of the A/6 compressor, and the steel tube in the A/C hose to the compressor. I think in 64 when A/C mufflers were first installed, the Freon/oil kept them clean, but once any moisture got in the system it was flash rust city in the muffler. Below, left, one of many attempts to flush. Below right, even after four flushes, I still got small black dots of rust out, shown toward the bottom of the container.


As of this writing, all the A/C lines have been removed and shipped to Old Air Products for rebuilding, including the line with the muffler. There is no supplier for Buick rebuild or newly manufactured A/C mufflers. It is not necessary to put an A/C muffler back into the system, but I'd like it to look as original as possible. I believe Old Air Products may have an Oldsmobile muffler that will likely look the part. Below, all the hose parts before being shipped out to them.