A lot of automatically controlled climate control systems on cars since about 1967 use "vacuum motors" to operate the dampers in the air boxes. These are usually just a bellows and light return spring that are controlled by the presence or absence of a vacuum.
I removed the airbox unit and replaced these actuators in my parent's 1972 Cadillac around 1990. It was a very successful result; however, I had to virtually dismantle and reassemble the entire Cadillac dash over 3 days to replace these "vacuum motor" components. I think they put this airbox sub-assembly on the line first and build the car around it.
I did a similar task in 1979 when I installed factory AC into the dash of my parents 1975 GMC Motor Home. I used a car AC compressor, dryer, muffler, expansion valve, condensors, and a new GMC airbox with vacuum motors, heater core, and evaporator installed. This also required a large amount of dismantling and reassembling. this also required finding a set of OEM accessory brackets that would permit mounting all the accessories including the compressor onto the 455 Olds engine without interference. The whole job took me 2 weeks of my summer break from college before I started my summer job. My dad then added the refrigeration oil and charged the 4.0# Freon 12 system. It worked very well, even visiting in the 107+ degree heat of Oklahoma, Kansas, and New Mexico.
These "vcuum motor" actuators are not unique to GM, because I had a similar issue with my 1987 Ford Taurus SW. I never got to dismantling the dash and replacing the defective components; so, this car had the heat and AC come out at the floor (no defroster action, and poor AC circulation through the car.). I knew how to pick my way through that repair, but never got the 2-3 days dedicated to that fix from when it broke in 1995 prior to selling it in 1998.
Fifty-six-year-old Pasquale Russo has been doing metalwork for more than 30 years in a tiny southern Italy village. Many craftsmen like him brought with them fabrication skills when they came from the Old World to America.
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