David,
My car also has the rear window defroster, the heated glass version was still not available in 1967 so all cars that had that option had the blower type. I heard that a few 1968 Rivieras had the heated glass but it was officially available on the 1969 Riviera and the following year on other full size Buick models. The blower-type rear defroster remained available as a cheaper alternative for a while. The 1966-70 Rivieras that have the blower-type rear window defroster have a molded plastic grille over the blower on their package shelf. These grilles didn't age well and many have turned into dust over the years while the plastic covering of the package shelf remains intact! My grille is still good and I bought a spare just in case it would start to disintegrate. Most other 1960's GM cars like my 1965 and my former 1968 Wildcat have a metal grille and the seventies cars that still had a blower-type defroster had a plastic grille that was more durable and made of a different black plastic. Unfortunately, the plastic used in the rest of the interiors of most 1971 and newer GM cars didn't hold that well!
About A/C
Some cars, including your father's 1967 Riviera with the Automatic Climate Control had their a/c compressor working in all settings except "OFF" and "VENT". But those with manual a/c didn't have that yet.
The 1968 Buick manual a/c control panel did include DE-FOG and DE-ICE but neither positions engaged the a/c compressor. It still engaged only in REC and A/C and the system had to be set on "HTR" to let some air go through the defrost outlets.
In the first link, there's a note that suggests running the system on A/C or REC for 30 seconds before switching to DE-FOG or DE-ICE but the manual isn't clear about the fact that you also need to move the selector to HTR if you want air to come from anywhere else than the 3 air conditioning outlets in the dashboard... Another thing that the manual doesn't say is that switching the A/C on for 30 seconds doesn't really help. I tried it!
Again, the automatic system allowed using the defrost position while the compressor was running. In both 1967 and 1968, the automatic system was much better on paper than the manual one. Unfortunately, it didn't always work as it should!
See this link for a better view of the 1968 Buick manual A/C controls.
And a similar conversation on Flickr about A/C systems!
[this post was last edited: 7/8/2014-03:48]
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