IML: Defroster Setting and Compressor Activation and Dual A/C Presumptions

["Eric" <gearhead@xxxxxxxxxxx>]

For historical purposes, I'll mention that in my post mid-year 1972 Newport 
w/the standard manual a/c, the compressor comes on when the Defrost is 
selected. For Imperials with AutoTemp, wasn't the compressor always engaged 
whenever the system was in any operating position? Maybe I have that 
incorrect.

1972 was an interesting year for the manual a/c equipped cars. Initially 
designed, the compressor always ran, all the time in any position and even 
in the off position, with the intention of keeping the interior 
dehumidified, which I believe was not the way the 1971 and earlier cars 
were. Mid year, there was a design change to the interior side of the heater 
box and a change to have the compressor run only in the a/c and defroster 
positions. When the button was pulled out, the compressor could be disabled, 
unless the temp lever was fully to the cold where a micro switch was 
incorporated into the lever assembly keeping the compressor running, and 
would override pulling out the button.
As I recall it explained, the ealier type of heater box used a type of 
fastener around the perimeter of the box that encouraged the box to warp and 
then drip water off the a/c coils into the passenger footwell. The later 
type of fasterners fixed this.
Thats probably more than anyone wanted to know about non-AutoTemp units, 
though I think I've heard of some of this era Imperial with the AutoTemp 
delete option so maybe this is applicable to some '72 and later Imperials.

Someone mentioned wondering why the rear a/c unit was ever used in that the 
front unit worked so well. It's to my estimation that the AirTemp Division 
had a bunch of these rear units manufactured as this was the standard 
placement for the a/c equipment in the 50's. I'll presume they had an 
inventory of these when front mounted evaporators and venting became 
designed into the cowl and dash, and they opted to market dual a/c as a 
luxury item thereby unloading the stock of rear a/c assemblies. It is 
surprizing that they redesigned the unit in about '64 or '65 as a smaller 
unit, perhaps they sold enough to be profitable in the past few years and 
figured that the next 9-10 years of dual a/c Imperials and Town & Country 
wagons would warrant keeping this exclusive Chrysler Corporation only 
option.

Eric
'63 Crown Four-Door w/dual a/c
'63 Plymouth Belvedere Four-Door sedan w/no a/c
'72 Newport Custom sedan w/working AirTemp
_____________________________________________________
I believe it was not until 1972 or even 1974 when they finally tied in =
the
 A/C compressor to the defrost position on the climate control.



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