The muffler does just that, muffles/smooooths the gas flow. The gas is not one smooth flow, but a flow of pressure spikes, positive and negative.
On my '77 Camaro (which had no OEM a/c line muffler), one day I went to lunch. It was a warmer spring day, so I turned on the a/c. When ever the compressor was running (CCOT system), there was a new hummm from under the hood. Seems that the smoooth running A-6 GM compressor did not have a smooooth gas flow, so the condenser was humminng as a result. Once I knew what it was, I didn't worry about it, but did not like it. Extended warranty bought a new compressor, but the hum returned.
Our shop foreman knew of an auto supply that had a large selection of a/c parts. He told me who to see and I took the car over there to get the muffler and fittings to make things work.
In my research, it seemed that all Pontiac and other Chevrolets had the muffler, but the Camaros did not, in those years. With the new muffler upgrade, all has been quiet for well past 700k+miles (not a typo).
The muffler can be one of those "little things" which can be deleted at the OEM level if some money needs to be removed from the car's cost, easily and quickly, but also added back in if there are issues with a/c system sounds later on.
So, YEP it needs to be there . . .
CBODY67
