Auto Temp II Overview - another video by "Adam", whose subjects are usually large vehicles from the late 60s/early 70s, the ones we focus on


Old Man with a Hat
FCBO Gold Member
Oct 8, 2011
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I had not seen this video by Adam before so I thought I would post it here. It is just an overview since it lacks in any real detail and is a little oversimplified but it does provide some perspective as to why it is preferable to other Autotemp systems of this timeframe.

He alludes to replacement of the control box underhood as being the only likely component needing replacing when the system doesn't operate as designed. The reality is that there are also a series of check valves in the many vacuum hoses that must be working properly for the system to even activate at all and there is also an electronic "amplifier" placed in the glovebox area that is part of the control system. If either of those items goes out, the system will not work properly as well. The check valves are not robust and do go bad over time, so use of the OBD II Chrysler tester is also worth having when trying to diagnose the Autotemp II system.

Adam's car is a very low mileage (12K miles) 1972 Imperial Le Baron that he covers in detail in another of his videos, one previously owned by the late Syd Meade so perhaps the system in that car did not work when he took possession of it.

I like that the video highlights the superior design of the Autotemp II system in the 1971-1973 fuselage cars wherein most of the functioning system is located under hood in one control unit and is very easy to replace - it was so good for that time period that Mercedes bought the patent rights for it and since Mercedes goes to great lengths to ensure that replacement parts are available for even very old models, that is the reason those controllers are still available in the aftermarket as rebuilt units made by Performance Analysis Company (the amplifier is also available rebuilt).

In the Autotemp 1 system, the controllers are long gone and unavailable for any source nos so those systems are complex and the control unit located in the lower right kick panel was vacuum controlled with a large servo that ended up leaking in short order when the various rubber seals went bad. In the Autotemp II+ systems equipped in the "formal" C bodies from 1974 thru 1978 model years. the system was split into two control units, one for operating the system buried deep in the instrument panel and another controller separate from the first one. Accessing the control activated by the vehicle driver/passenger was really bad, being buried deep in the instrument panel and required tearing nearly the whole dash apart to access it and them trying to put the instrument panel back together was a nightmare of ill fitting cheap plastics and difficult to get back together again as original. As with other components in the Formals, cost cutting was too rampant since the Corporation was sliding into bankruptcy in that timeframe and management was desperate to save costs - unfortunately, the company did go bankrupt circa 1980 anyway, so the cost cutting was really not helpful.

So the Autotemp II initial design really was a superior such system and even GM had trouble matching its relatively easy accessibility and ease of repair. Mercedes wasn't slow to pick up on it either, which also says something.
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Excellent reply




I had a very long discussion with the supplier of these Autotemp II controllers shown above. I was very impressed with his knowledge of these systems and determination in striving for the absolute best quality products possible. You can't go wrong with this guy and also Performance Analysis puts out a very good product too. I do understand the advantages of this product regarding the aluminum alloys used in the body of the controller that give them the potential for very long life. A very honest guy as is the one at Performance Analysis Company as well.

It is encouraging to see these suppliers wanting to please their customers as their highest priority.